How to align a chain on a single speed My bicycle currently has poor chainring/rear sprocket alignment (as in the chain at the front is more than a chain's width from the chain at the rear). I'm wondering what the procedure is to correct this alignment, because currently riding the bike damages the chain. (I have already moved the wheel as far across as i can using washers)

To adjust chainline, you can:

At the back

use spacers between the hub and cog

At the front

use a longer/shorter bb spindle (as Kibbee says)
use spacers on the bb cups (as Mark W says)
use chainring washers (and likely different bolts) to adjust the position of the chainring on the crank

I'm struggling to think of any more options.

The only other thing I could think of is that if you do end up with an imperfect chainline, despite your every effort, then a 3/32" chain will be more forgiving than a 1/8" chain. 3/32" chains are designed to be able to traverse cassettes so have a little more flexibility in them.

You can not. The real problem is the hub being not wide enough. You would need to get a wider hub. Single speed systems have wider hubs.


How should I negotiate price with bicycle salespeople? Aside from just knowing the best time to make the purchase of your bike, what other specific tactics can I make use of in negotiating price on a bike? For instance, what devalues a bike aside from just wear and tear, and how can I use these to get a better price on a bike?

Note:
I appreciate all the comments about LBS and local patronage of merchants is something we can all support. However, like going to buy a car, there are always things to know about a product that (when negotiating) play in the favor of merchants (overvalues the car: like when you had to get on a waiting list to get a Prius) and in the favor of buyers (devalues: when you had to be wary of your gas pedal buying a Prius). This is a question to benefit buyers of bikes.

Don't expect much until you know the guys that work at a bike shop. I bought my first road bike (a single speed) from my not-so-local LBS because it was on sale (45 miles from my house, with several bike shops in between). In the process, I discovered that I got along well with the guys that work there. In return for our growing relationship, they started giving me pointers about maintenance, and discounts on accessories (computer, bar tape, etc).

When I referred my father-in-law to them to get a bike (he's a doctor and doesn't have the same price constraints that I do) they gave him a pretty good deal because I sent him. I have no doubt that when I've saved my pennies enough to budget for a new bike I'll get as good a deal as they can offer me, without having to ask for a deal.

Most bike shop employees and owners could make a lot more money doing something else, but own/work at a bike shop because they love cycling. I appreciated the desire to stretch your dollars as far as they'll go, but nobody is entitled to special deals without earning them.

Bottom line is NO a bike shop will not lower the price for you just because you haggled! The profit margin is low on bikes and no lead way to discount.  Some bike stores will discount their bikes when the next year models come out.  Look for a non profit shop in the area where you can volunteer and build a bike for very little.


Schwalbe Marathon Plus vs Continental Gator Hardshell Schwalbe Marathon Plus and Continental Gatorskin are two of the most established and most-discussed lines of tyres on this site (171 results and 90 results respectively if you search "Marathon Plus" and "Gatorskin" on the site). Continental Gator Hardshell is a puncture-resistant version which competes directly with Marathon Plus.
I have been comparing the characteristics of both tires and am not sure which I would prefer for commuting. For the sake of putting numbers on each tire, Marathon Plus could have something like on the order of 1.1x more rolling resistance and 350g extra weight per tyre, but 1.3x more puncture resistance (according to one site's imperfect measurements).
If you had to choose one over the other for a five-mile urban commute (trying to avoid a couple of smashed bottles each way) and could buy them at the same price, which would you choose (taking into account rolling resistance, weight, puncture resistance, and other relevant factors)?

There are reviews of both tires on bicyclerollingresistance.com: https://www.bicyclerollingresistance.com/tour-reviews/schwalbe-marathon-plus-2015 and https://www.bicyclerollingresistance.com/road-bike-reviews/continental-gator-hardshell
The Continental Gator Hardshell is considered a road bike tire, albeit a very puncture resistant one. The Schwalbe Marathon Plus is a touring tire. It’s heavier, available in wider versions, more puncture resistant and has a bit of tread.
If you need/want more than 32mm width you are out of luck with the Hardshell.
Otherwise it pretty much boils down to personal preference. Both are high quality tires with their own strengths and weaknesses. Personally I can live with patching a tube every month or so. At the same time I like to go fast/far and light. The Gator Hardshell is pretty much the heaviest, slowest tire I would even consider using. The Schwalbe Marathon plus is way too heavy and slow for me.
I’m currently using Continental GP 4 Seasons on my travel cyclocross. In the city I have about 2 or 3 punctures per year (2*6km commute). I can live with that.
If you need/want all the puncture resistance you can get there is no way around the Marathon Plus.

Schwalbe Marathon Plus and Continental Gatorskin are two of the most established and most-discussed lines of tyres on this site (170 results and 89 results respectively if you search them in "Questions").

If you had to choose one over the other for a five-mile urban commute (trying to avoid a couple of smashed bottles each way) and could buy them at the same price, which would you choose (taking into account rolling resistance, weight, puncture resistance, and other relevant factors)?

I would pick neither. Both have way too high rolling resistance.
I have used Continental Grand Prix 5000 for the last 2000 km. Not a single puncture in that period.
The problem with Marathon Plus is its ridiculous rolling resistance. It's clearly out of the question.
Gator Hardshell has similar rolling resistance to GatorSkin. I have simulated GatorSkin and GP 5000, and the result is you lose 1.7 minutes with GatorSkin when compared to GP 5000 in a 5+5 mile commute there and back. Puncture repair with proper tools takes perhaps 5 minutes, so if you get punctures more rarely than once every three days, it's a better choice to minimize rolling resistance than it is to maximize puncture resistance.
Somebody could argue that arriving 5 minutes late at work is alone a reason to go for more predictable commute time with high puncture resistance and high rolling resistance tire, but then again 5 minutes is the difference of headwind and no headwind, so you have to be prepared to be 5 minutes late anyway.
Note my 2000 km during which I had no punctures with GP 5000 corresponds to 124 working days with 5+5 mile commute there and back. Way more than 3!
But, if there was no other choice than Gator Hardshell and Marathon Plus, I would clearly pick the Gator Hardshell and suffer its high rolling resistance, because the rolling resistance of Gator Hardshell is still better than that of Marathon Plus.
Weight is not a consideration. All similar tires weigh about the same, with perhaps minimal differences due to bead material (kevlar vs steel wire). Besides, low weight is overrated. Typically what determines your speed are air resistance and rolling resistance, not weight. Especially in consumable parts like tires, chains, sprockets, etc. saving weight is not advisable because you have to pay a lot to get a lightweight product that will last only few thousand kilometers.
About the width: I currently use 28mm due to historical reasons (when I bought my first road bike tire, it was GatorSkin 28mm because no wider variant was available back then). I mainly have stayed with the 28mm width because I have found it to work for me and have high investment in 28mm equipment. If I was to choose a tire today with no existing stock, I would go for 32mm.


Minimum mountain groupset hard enough to resist abuse I'm looking to upgrade my mountain bike and I would like to get something better than I have, if justified. I've never ridden any groupset better than alivio/deore, which work ok for me and have tolerated some abuse. I'm riding harder these days and I would like to know if a better groupset would be more durable. I'm not very concerned with the "bling" factor or the weight, just something that will stand some "serious" trail. Any thoughts? Please feel free to elaborate on the brand or isolated parts if you want.

Edit: I would like to make the question more specific, because my intention is not to start a discussion about Shimano or SRAM. I assume that both brands are ok. Let's see: I want the bike to do cross country but not downhill. When I say that I ride "harder" I mean that I've gone from following a trail to now jump, go over rocks, some mud, a bit of water, etc ... That has made my drivetrain to get out of tune and drop the chain frequently, even I if adjust it before every ride. I am discarding here my shifting technique as a source of problems because I know how to shift correctly. I thus want to know at which level of the groupset hierarchies (no matter if it is Shimano or SRAM) this is less frequent. That is, that you adjust the gears and they stay adjusted for more than a ride even after some abuse. If I am going to need to adjust the gears every time no matter if the group is a XTR or a Acera, well, then I will rather save my money. But if XTR is stronger and stays tuned for more time, then I don't mind paying for the quality. I would like to hear from experienced riders if they noticed (or didn't) a great improvement in reliability (not weight or coolness-factor) when they bought a more expensive groupset. I hope that the question is clearer now.

Thanks!

Note: this is mostly based on my personal experience. Its an
  incredibly subjective subject, so there is no right answer. Keep in
  mind that in reality one level up or down will be completely
  unnoticeable performance difference to most riders.

XT is considered the "Sweet spot" for performance, weight and durability.  Probably X9 in the SRAM range. XTR and X0 are for sponsored riders, rich competitive riders and those that have to be seen to have the best because they will never be...

Alivo is definitely entry level and although it starts out OK, is less durable and quickly becomes unreliable if used hard. Deore and X7 are known for good durability - not up to  XT in quality and feel and durability - but not far behind. IMHO Deore and X7 are a good price point for a budget conscious weekend warrior - especially if you can get last years stuff at a good price.

So depending on your budget, I would recommend looking towards Deore  or SRAM X7 level gear. From you post, I suspect XT is too good for the bike and you won't get the advantage of the extra $$$.

So where is you problem? The bike "was good once" - so the level of the gear is not the problem. I suspect the gear on it is worn out.....

I would start with a close look at the chain lines - check the Bottom bracket for movement, and check the derailleur hanger for alignment (LBS has a tool for this). Check the cables are moving freely - I suggest replace the rear derailleur if you have any doubt or its more than a year old. All this is low or no cost and can make an enormous difference if they are out.

Assuming these are OK, I would start with a closer look at the chain, cluster and chain rings. Especially check the chain is clean and free running, with no tight links. If these have not been replaced recently, its the first thing to consider. At the same time, check the derailleur for movement - this is hard if you are not experienced. A little is OK, a lot not - and how to tell - got the LBS and look at some new bikes, look at some mates bikes.

Here is where you can start throwing money into a seemingly bottom less pit, so be careful. Don't feel the need to replace with higher spec components; don't go up more than 1, at a stretch 2 levels - so Alivio to Deore is OK, Alivio to XT - think very carefully. Keep it all about the same.

You are likely to find that parts prices mean an upgrade of bike is worth considering. A MTB is more than the drive line - tires, shocks, frame geometry all make a bigger difference than smooth gear changes.

If you're looking for a Shimano group set, I prefer the Shimano groupset xt. It is budget friendly. You'll love the quality and the performance of this brand and unlike some of the other group sets it works smoothly.


New to Drop bar Road Bike, severe upper back/neck pains Took my new Cannondale out yesterday and 40 mins into ride started getting pains just below neck top between shoulder blades, the bike is the right size a 56 I am 179cm, is this due to me not being used the drop bar posture or am I doing something wrong ? Have been told it may take a few rides for the muscles to get used to the posture, just mystified any advice would be welcome.

You should try a professional bike fit.

Just because you are 179 cm doesn't mean a 56 is right for you (the sizing of a bike with a given number varies on the type of bike and manufacturer and model). Normally, when you switch to drop bars, you will be sore (but pain is different, and should be alarming, though going for a 40 minute ride while just starting out may be a bit much). The geometry of the bike can also cause problems - racers may cause more pain than touring bikes due to their more aggressive geometry, for example.

Here are some tips from sheldon brown on pain, and what to do about it.

yes i have been riding for long time but started to get pain when  i went out on longer rides upper back neck i have raised the stem shortened it changed bars wider  seat before after  done exercises physio changed bike frames  done the bike dynamics bike sizing check i still get pain i should be able to ride a 100 easily but pain in upper back stops me as most bike s go up in size the top tube lenghthens as i need shorter top tube bigger head steerer its more like trial and error which is expensive if you havent got much money .
all i can say is people change there bike size and ride diffrent bikes to prevent rsi i reckon that what they do in the tour as their bike positions seem a times impossible set ups like riding on the hoods they are very upright back seems very relaxed then they appear over stretched its not all its cut out to be as many pros are million airs and have many bikes and team of massages on tap and pro bike fitters there is a lot not being said
ebay is full of frames for sale why people are in pain. or materialism if there was no pain there would be no need to change frames all the time
the cycling industry is a big racket !expensive and complicated


Frame failure sudden death? I had a serious accident, my fork suddenly snapped when riding.
I sent my bike for repair (to get a new fork installed) and the guys at the shop hammered the frame in place, as apparently the frame bent from the crash.
Now after the very scary crash I had, I am wondering if I should even ride the bike in that condition? I know it is impossible to predict how much time will it take for it to fail, but other than checking very often if the area next to the bumps changes, what else can I do? I know that getting new pieces welded is not an option as it is hard to weld aluminum and it is probably less expensive or equally expensive just to get a new frame.

If an aluminium frame has to be bent back into alignment, it's trashed. Aluminium cannot be deformed without causing weakness in the material.

If the bicycle repair shop literally hit the seat stays with a hammer near the dropouts to straighten the frame is probably weakened in those areas and is very likely unsafe. I personally would not ride that frame.

The bicycle repair shop should have told you the frame was un-repairable and not replaced the fork. Maybe they wanted to make some money of a repair job but I can't believe they passed up an opportunity to sell you a new bike.

Bending aluminium does not cause sudden failure. Take a piece of aluminium and try it your self.  Like any metal, repeatedly bending aluminium will gradually make it weaker. (This is a common failure mechanism for very old steel bikes).  Unlike steel, aluminium has no "absolute minimum" value for softness (which enables you to specify intrinsically safe steel components). For this reason, aluminium parts have to be over-specified, because they always just get gradually softer and softer in use.

Bicycle frames (especially expensive bicycle frames) are designed to be as light as possible. For this reason they are shaped into the most efficient shape possible. If you dent a tube out of shape, it will not be as strong as it would be. If you dent a tube on any bicycle, it will materially weaken the tube. This is not because it is Aluminium or Steel: it is because it is a tube.  On a bicycle some tubes are critical (the front forks, the head piece), some tubes are not critical (the cross bars: you can just keep on riding with broken cross bars), but will critical in traffic or when making a sharp turn on a fast downhill. And some tubes barely matter at all (the rear wheel posts), as you know if you've ever had one fail at speed in traffic.

The pictures you've posted show damage that hardly matters at all, at a location that matters very little. The effect of softening is marginal (bicycle alloys are selected for handling 1000's of repeated stress cycles), and it's a location where the change in shape is less than critical. The bike shop (which doubtless see lots of damaged bikes discarded), didn't even think it was worth trying to sell you a new bike.

If you ride a frame long enough and hard enough, it will fail. This frame may fail at the rear wheel, or, the way you're riding it, you may do the front forks again first.


Removing Seat Post rusted into downtube I have an old steel frame (Columbus Number 2 I think) that has the seat post (Suntour Superbe Pro - see, I said it was old!) rusted in. I have tried lots of WD-40 but it will not budge.
Any tips on how I can get it out without having to cut the frame up?

Before you take any more forceful measures, it may be a good idea to think a little about chemistry:

'Rust' is typically the name put on any type of corrosion, but technically & specifically, it is the corrosion of iron (or steel) to form iron-oxides.
Although your bicycle is most definitely steel, your seatpost is not -- it's aluminum-alloy, which does not 'rust', but definitely corrodes (creating aluminum oxide).
WD-40 is a penetrating oil which is designed to, amongst other things, break up iron-oxides. However, it is pretty much useless against aluminum-oxides, especially when they have already corroded & bonded.
Ammonia, however, is spectacularly good at eliminating aluminum-oxides.

Therefore, if WD-40 isn't doing the trick, get some ammonia, apply it in a similar fashion, and let it sit. It may just be all you need!

Using a small butane torch, heat the seat post till it breaks free from the frame.


Which kind of tube valve is the best? What kind of valve is the best one, a Presta valve (6mm) or a Schrader valve (8mm).
Which has the best reliability, which one is easiest to fix a flat on?

Presta's main benefit is more about how the valve functions, in regards to getting pumped up to higher pressures.  Because the stem of the valve needs pressure in the pump head to get high enough before it pushes the valve stem in, and start flowing air into the tire, when you try to get to 120 to 160 lbs of pressure it works better than a Schrader valve where the valve stem is depressed the whole time, back pressure can leak out.

Otherwise I would say tomato - tomahto (potato - potaato?)

A schrader valve require air pressure to open, A presta does not.

The biggest difference will seen when airing up a tire past 100+lbs, A shcrader will take more pumps to get from 100 to 110, because at that high of a pressure, more air is required to open the valve, whereas on a presta all the air goes into airing up the tire.


What and where is the weeping port on Shimano MTB brake levers? I understand that when you overfill some models of Shimano hydraulic brakes with oil, the excess will flow out of a one-way valve called weeping port, but cannot find any technical documents, pictures or videos that point out where this valve actually is. I suspect it is the conspicuous, but rarely mentioned, cannon-resembling big round ending on top of many Shimano brake lever models, which I highlight in the picture below.

The reason I am asking is because when I pushed back my caliper pistons to install new brake pads today,  a lot of oil suddenly squirted from this part of the lever. The lever became very soft of course, so I bled it and it felt fine, but the oil continued to seep (or, well, weep) slightly as I rode the bike later.
So, is this indeed the weeping port and how exactly should it operate? Does it just let the excess oil out after which the brake functions normally - as mine does so far, but with oil still flowing out very slightly - or should it be repaired?

From my understanding, that port is a pressure compensation port. When the oil level changes because of pad wear, temperature, or a leak, air will enter through that port to balance the reservoir’s pressure. The oil is kept sealed by the membrane, which you might have torn due to overfilling.
There’s a small port in the side of the master cylinder that connects the reservoir to the cylinder. When you actuate the lever, the piston travels past the port, allowing the system to build up pressure. When you release the lever, the port opens up again and does any necessary compensation.

From my knowledge with MTB Brakes there should not be oil coming out anywhere, as braking relies on putting pressure into the lines.


How to prevent Brooks Cambium C17 saddle from wearing through pants I've got a Brooks Cambium C17 saddle, and as others have noted (see "long term experience" heading), the fabric covering has worn through the seat of my pants from abrasion and has resulted in one pair of pants tearing just a few weeks after riding on this saddle.

Does anyone have a good remedy for this?

I'm considering a rain cover like so, but I'm not sure how long that would last before it tears through as well.

I wrote an email to Brooks about a recommendation for the problem, but I've yet to hear back.

My seat height is such that my legs are almost fully extended at the bottom of the pedal stroke. I have not noticed this problem on other saddles.

The pants that wore through (and I have another pair of the same pants that is wearing thin in the seat as well) are Dockers Life Khakis like this - a cotton / polyester blend that has been fairly durable in my years riding in other saddles.

It's difficult to know as you haven't said what your are wearing exactly. I have this exact saddle and have covered approx 8,000km on it- wearing out no clothing (that I have noticed). I'd suggest that you saddle position is possibly not quite correct and you are moving slightly through the pedal stroke- causing friction and wearing through the clothes you are wearing. I'd look at possibly moving your saddle up, as having it too low tends to cause the hips to move outwards/in on each stroke. Alternatively, you are wearing clothing that is not designed with cycling in mind & should perhaps look at buying some.

Ride out of the saddle for the entire commute. Or get pants with a tougher crotch. There are plenty of companies that make commuter type pants that have reinforced crotches to slow the destruction of the pants.


Is this a real Concorde or just a replica? I'm confused with this, the lugs in this bike look identical with another Concorde but the tubing sticker clearly says "Reynolds". (Concorde only uses Colombus, right?)

I have a 1990s Concorde Americas that has Tange tubing. I bought it when it was just a couple of years old.


How to measure chainring / cog wear? Other than attempting to estimate whether a chainring or cog is worn and needs replaced by eyballing it, is there any way to measure the wear on chainrings or cassette cogs so you can determine whether they should be replaced?  What tools can be used to accomplish this?

Because there exist so many cassette styles and tooth profiles, no universal tool for measuring cassette wear exists.

One good advice to assist visual inspection is this. We all have our favorite speeds. Compare the most worn 2-3 cogs with the rest. If their profile is very different, the cassete is probably worn. The video documents how to do that.

There are many variables in determining whether you have a worn chainring or cassette. Visual inspection helps and noting the kilometres racked up should also help.

If you have set up your mech's correctly you will know you have wear when your chain starts to skip, especially under load. Visual inspection should then confirm your wear.

Park Tools do a CHAIN wear tool [CC-2] but that will not determine cassette or chainring wear.  When replacing a cassette you should always replace the chain. Worn chains will reduce the life of cassettes and chainrings considerable due to the chain being worn to the form of the previous cassette/chainring.

Here is a video of the pro's confirming the above:

Hope this helps.

Cassettes are harder to measure.  For example they adjust spacing for IG (Interactive Glide).

Chain is something you can easily measure.
And it is the cheapest and easiest component of the drive train to replace.
A stretched chain will increase the wear on cassette and chain ring.

Measure chain
Replace chain when stretched
For sure replace cassette when chain jumps on a new chain
Or a visual inspection of the cassette - compare it to picture or if you have a replacement on hand compare it to the new.
Chain ring
Visual inspection is a good guide.  If the teeth are pointed it is worn.

Cheap it (optional)
At most you are gong to get 3 chains.
In the 3rd chain wait for it to skip and replace chain, cassette, and chain ring.
As Hick commented a chain ring will typically last two cassettes so only cheap it when you know the chain ring is also on its last leg.


How do I efficiently shift gears on a road bike with downtube shifters? I have bought a vintage Campagnolo road bike, so the shifters are on the down tube.

I own a mountain bike and i am used to changing gears on that one, but don't know the proper technique to change on this one.

Update

I am concerned about the technique (which hand to use, how do you keep the other on the handlebar)
how do you know to shift in the correct position without an indexed shifter
other tips and tricks

Downtube shifters will really get you in touch with your bike--more than with many other shifting systems, I believe that I can actually FEEL the rear derailleur moving in my hand when I use them.

Needless to say, I ride a lot of old road bikes.

You will quickly gain the control to shift either from various hand positions on your road bars.  Assuming the bike fits you, you should ultimately be able to use the shifters from nearly any position.  You will, of course, use the right hand to shift the rear derailleur and the left hand to shift the front.

I will talk mostly about shifting the rear derailleur, as it will require the most control and finesse.

Note also that these shifters each have two main parts that are pertinent here, the LEVER and the BARREL.  The lever is pretty obvious--it's the usually-flattened handle that sticks out.  The barrel is the round bit which is attached to the frame.  The cable wraps around this round bit--as you turn the shifter, more or less cable is wrapped which is how the shifter moves the cable and thus the derailleur.

Ordinarily, when I reach down and the bike is in high gear--with the shift lever all the way forward and parallel with the downtube--I will grasp the lever by wrapping the thumb of my right hand over the end of the shift lever.  I press the side of my pointer finger against it and slowly pull back.  This motion has less control over precise gearing and is best suited for quickly downshifting before climbing.

If I am already in low gear and the shifter is out away from the downtube, I usually actually grasp the entire lever with my right hand.  In this mode, the tip of my thumb is on the barrel and my fingers are all wrapped around the shift lever.  Motion in either direction from this position can be very precise.  As I said, you can feel the derailleur move if you're cables are new and well-greased.

It's a good setup for shifters, in my opinion.  I can't say that I prefer downtube to integrated, but as far as simplicity is concerned... nothing beats it.

Except, perhaps, Sheldon Brown reaching down and putting his forefinger on the chain to move from upper to lower chainrings.

If you get a chance at the library, check out Understanding, Maintaining, and Riding the Ten-Speed Bicycle by Denise De la Rosa and Michael Kolin (Rodale Press, 1979).  This book describes shifting and using downtube shifters rather well, right down to the groovy 70's costume.  De la Rosa describes another method of hanging the thumb (I think) off of the top tube while reaching with the same hand's fingers down to the shift lever.  This only would work on a frame smaller than mine, but it's another piece of cycling history.

I hope this helps.  It certainly took my mind off my work for a few minutes!

The only thing I add is always shift with your left hand. With only one hand on the handlebar, which means only one hand can immediately brake, you would want your right hand so you pull your rear brake. No sense going over your handlebars if you have to brake fast.


Quiet and strong chain recommendation for fixed gear commuter bike I went through a couple of chains on my fixie bike, but I was not too happy with any of them.
Basically they seemed pretty noisy when more pressure was applied where cycling.

Could you recommend one that would be both strong and quiet.

Thanks

Chain noise is not completely avoidable on fixed-gears, due to the stress from chain tension, etc. However, there are many types of chain which would be inappropriate to use and would cause extra noise.

Be sure to purchase a 'track' chain (some are produced by Miche, Izumi, and KMC) and expect to pay $20+ for a quality chain.

Also, be sure to keep your chain clean and well lubricated! Even on regular bikes, the majority of chain noise comes from a dry chain.

You might want to read this chain survey. See page 44 and onwards.

Lately I have been using Dumonde lube on my chain and I have been pretty satisfied. It makes it easy to keep the drive-train clean, but it does require the chain be completely degreased prior to the first application. My experience has been consistent with the review.


Jockey pulley (upper jockey wheel) suddenly not engaging with the chain when in the three largest (easiest) cogs on the big ring only The gears work fine across the whole cassette on the inner ring but all of a sudden the chain has stopped engaging with the upper jockey wheel when in the big ring and three largest (easiest) sprockets of the rear derailleur.

The jockey pulley looks out of position when this happens (almost horizontal to the lower tension pulley jockey wheel - the chain then simply isn't reaching the upper jockey wheel) and the chain makes an unholy racket with the drive train eventually seizing up entirely until I shift into smaller (harder) sprockets.

This seemed to occur straight after I removed then replaced the rear wheel, catching it a little on the brake pads as I did, which resulted in a bit of a clunky removal.

Is this likely to be the result of a bent, misaligned rear derailleur?

It would help if you could post a photograph, but what I'm picturing from your description is that when you shift onto any of the three largest cogs in the back while you're on the large chainring the derailleur cage is pulled almost horizontal and the jockey wheel disengaged from the chain.

To me, this sounds like your chain is too short. Since chains don't magically shrink what I think happened was that when you put the wheel back on the bike you pulled it further back in the dropouts than its original position and now the chain has farther to go. So, I think all you would need to do is to move the wheel forward in the dropouts.

All of this assumes that you have horizontal dropouts, if you have vertical dropouts I'm completely wrong…

As previously stated, a picture or two would help answer this question accurately. Even without a picture, some information is missing. What kind of cassette is it, and how many front chain rings do you have? Because if you have 3 cogs on the front, (depending how many gears you have on your cassette, for this answer I'll assume you have at least 9), then running any of your large cogs on the rear cassette with your large chainring on the front (cross chaining) puts considerable stress on your drive train and all of its components.

Without all of the information, I can only speculate what I believe your problem is. Listed is a picture explaining it.

If this is the case, and especially if you ride in this manner often, your rear mech might be permanently damaged. I would recommend taking it to your LBS to see if they can help you out.


Adivce on what to do next with crunching / slipping gears About two weeks ago I took my bike to the local bike shop to get serviced. It was previously slipping gears under load and at the end I couldn't use the lowest gear going up hill it would just slip constantly.

I mentioned the crunching / slipping to the guy at the counter.

When I went to pick up my bike I was charge $170 bucks for two new set of brakes, replaced one bolt type thing which was apparantly shredded (called a cone or something along those lines) and to have all the gears properly set. I was also told that the rear derailleur arm was bent and this was straightened.

The bike only cost $100 from a reliable friend who only rode it ocassionally and the bike is 3 years old. So the service was comparitively costly compared to the cost of the whole bike.

In the past few days it has started slipping again under load which is what it was doing previously and it won't hold gear at all when in the very lowest 1 1 combination it always slips to 1 2. It is also very noisy when I sit in my average riding gear which is either in 4th or 5th in the rear gears. The crunching is slightly dangerous because it can happen taking off from traffic lights or when I put extra pressure on to leave an intersection / roundabout etc. when cars are waiting behind me.

The other thing is when I picked up my bike I asked about the slipping and the response was kind of like "ah, yeh, ah, that should be OK now" which sounded to me like they didn't take it for a significant ride after repairing.

On the other side, these guys are supposed to be reputable, they have been around for a few years and the bike is not a supermarket bike it was actually purchased in their shop and in their defence the bike worked and sounded like a dream when I took it out of the shop so it is possible they did take it for a test ride even if they didn't sound convincing when they said so.

I'm only an amateur so it is hard for me to describe what the problem is, it's like a split second crunch and it doesn't move down or up gear. Sometimes it feels like it is just slightly out of gear and then after riding for 2 minutes it will crunch for a second and then it will not crunch again unless I change to a different gear. Sometimes I can just sense that it isn't quite right and swith back and forward between gears. Although, when I look down at the rear gears it all looks settled even if it doesn't feel right.

I'm also not sure if it is the rear derailleur cogs where it is slipping or the gears, I have no idea because I can't visually spot it and can't tell exactly where the sensation is.

I would appreciate any advice on what my next steps should be?

That sounds like the rear cogs are worn, the likely fix is a new chain and set of cogs for the rear (you have to replace them both at the same time otherwise the problem will persist, perversely even worse).

I suspect the bike shop fixed/replaced the stuff that was obviously visibly knackered and hoped for the best.  In truth I suspect they needed to do what they did plus replace the cogs and chain, but they were hoping that wasn't the case because the bill would have been even higher.

In my experience bike shops don't tend to actually ride the bikes so they can miss stuff I wish they wouldn't.  That's one of the reasons I learnt to do my own maintenance.

In general the trick with bike shops is to check your bike before you sign off on the work, i.e. I ask to ride my bike around to test it before I leave the bike shop (and pay).  If I do find I still have a problem after leaving the bike shop  and paying I go straight back and explain the problem and say it's not quite sorted yet.  They are normally very reasonable and will sort the problem without additional charge, assuming it doesn't require new parts.

Your best bet is to go back to the bike shop and explain the problem isn't quite sorted and if possible demonstrate it to them.  It will cost more money though, it sucks but unfortunately bikes aren't generally that cheap when it comes to maintenance (compared to the initial cost of the bike).

I had a problem with what I thought was a slipping ratchet. Pulled it all down and cleaned it up, reassembled  ..  same problem. Then degreased/oiled chain. Problem fixed. Always look for the simple things first!!


What makes a great kids city bike? (and where can I find or how can I build one?) I have two children age 6 and 8. In good weather we often ride 10 or 20 miles in a day to school and misc activities. I'd like to get them city / commuter bikes but almost all of the kids bikes I can find are BMX, MTB, or beach cruiser.

However we mostly ride on paved surfaces and these styles aren't as efficient as a hybrid or 3 speed with narrower, higher pressure tires. I'd also like them to have fenders, racks, and water bottles. But I can't find such bikes at stores I've visited in the US or online.

What type of bike would be a good city commuter bike for kids? I am happy to extensively modify what is available, but am not sure where the best place to start would be.

So, if your kids are like most, they are going to be hard on bikes. They will jump off curbs, do wheelies, and likely toss them to the ground when they dismount. I recommend something that will take a bit of abuse. A bmx will take a beating but it is an awful commuter bike. Beach cruisers are not much better - and they won't take the abuse.

I recommend a hard tail mountain bike for most kids. A hard tail is one with only suspension in the front. You will want to make a single change to it, put on some slick road tires. A slick tire mountain bike can be fast, I recently had one fly by me on a 100-mile ride (and I am pretty fast)

A hard tail is a great choice because it is cheaper, lighter, and easier to maintain than one with suspension in the back as well. You can often find them for a good price used. They will accept all of the accessories that you mention.

Whatever you do, don't buy one from a department store. A used quality bike will be much better than a brand new one from a box store any day of the week.

You will need help finding a good one, quality varies a lot. Look for brands like specialized, giant, trek, Santa Cruz, though there are many others. Stop by your local bike shop and ask if they have one used, or bring in some ads from Craig's list. If you start by saying "I would like to get a bike and have you service it", they will be apt to help you more.

Also, pinkbike.com is a good source for used bikes and parts. You can filter for bike types, location, price, etc. Expect to pay at least $250 for a used one, and that is bottom end. Process will go up from there.

I hope that helps.

Cheers

Another option would be Islabikes, they are a UK company but now have a US operation based in Portland.

They are a specialist children's bike manufacturer with an emphasis on low weight and child specific components.


Tyre bulge when inflated, new Got some new bicycle tyres yesterday (CONTINENTAL COMFORT CONTACT 700 x 32c CITY COMMUTER ROAD) The tyre I fitted to rear wheel seems to have a bulge in sidewall. Took it off, looks ok inside. It feels perhaps a bit thinner where its bulging. The tube seems a bit big for the tyre but I doubt this could cause it?!? and the front is ok with same tube. Previous tyres were 35c.

The bulge is perhaps 10mm diameter and 1-2mm deep. Not very visible but immediately feel it if rotating the wheel.

They were from an ebay shop and arrived twisted / folded in half so as to be much smaller to post - wire bead type. They seem to spring back into normal shape when unpacking them, no visible damage. I assume the folding may have stretched/torn a cord?

Edit, I did remove, inspect, rotate and refit the tyre. The bulge was in the same part of the tyre, so its not the tube. I inflated to about 65psi.  Recommended on the label is 70, max 85.

I did see the other post, but that is showing a used, damaged tyre, rather than a brand new one. Thanks I will be sending it back.

Something is wrong with the casing. Not safe to ride. Sometimes the come from the factory that way, who knows why. Send it back and get it exchanged. Don't risk a catastrophic blowout.

Consider buying unbent (wire bead) tires from a local bike store,
not cheap, from ebay, imported from some country with no standards.


How often do you need to grease the crank? Haven't done maintenance on my bike in years.  Recently cleaned it up and repaired some spokes.  Greased the front and rear wheel bearings and degreased the chain.  Looks good but only thing didn't do was grease the crank.

It is likely, unless your bicycle is quite old, that it has sealed bearings in the crankset, so there is no real need to grease them yourself. It is good practice to visually inspect and clean them regularly, but they do not need deep maintenance unless you encounter rough movement or an unusual sound coming from them.

Ciitation: Bicycle industry work experience.

Depending on how often you use it but I give mine a going over around every 12 months as an annual service.


Does having bigger wheels mean less effort pedaling? Assuming that we are using a fixed-gear bicycle and width of the wheels are the same, I wondered, does having bigger wheels mean I need to less effort to get from point A to point B in an urban setting? I'm thinking based on the formula for circumference:

Where r is the radius of a bike wheel. Additionally when looking at this gif for a vertical visualization of circumference:

It appears that having bigger wheels will get you from point A to point B in an urban setting with less rotations by the wheel, but does that also mean I need to work less to get there? What about uphill? Does having bigger wheels help/hurt biking uphill?

Assuming a completely smooth road and neglecting the weight of the wheels, it makes no difference: you still need to do the same amount of work. Essentially, larger wheels give you a higher gear ratio, so doubling the diameter of the wheels would mean you'd only need to turn them half as many times, so you'd only need to turn the pedals half as many times, but you need to press twice as hard on them.

But, in reality, there are limits to what you can do. If you need to lift 100kg of wood, it's easier to lift 10kg at a time, even though the total work done is the same as when you lift the whole lot at once. Similarly, you'll be more physiologically efficent (and comfortable!) pedalling with certain ranges of cadence and force.

Bigger wheels roll over bumps better. As an easy thought experiment, consider a pit whose width is equal to the diameter of your wheel. Obviously, the wheel will fall right into the pit. But if you consider a wheel with twice that diameter, it will only drop a little way into the pit as it bridges over it.

In practice, though, there aren't a whole lot of wheel sizes to choose from.  Either you get a folding bike with small wheels, or you get a non-folding bike with wheels about 62cm/29in in diameter (or about 56cm/26in for mountain bikes).

tl;dr: No, in fact bigger wheel may mean more effort

Answering a question similar to this allowed me to get an admission in my esteemed institute. I will try not to get too technical, here we go.

 First of all (for sake of developing intuition), open the nearest window/door first with its handle, then close it, then open it again, this time use your palm keeping it as near to the hinge as possible.
-->

You are very correct in saying that C (circumference) is in fact 2 times PI times r (radius taken of wheel) and if we hide the constants we can safely say that C is directly proportional to r.

In plain english, distance covered (irrespective of road conditions, be it urban, wavy, or even inclined road) varies directly as radius of wheel.

Now, think about it, you can cover 100s of miles with virtually no effort if you are sitting in a bus. You yourself realize going uphill will be difficult, why? 1 meter is 1 meter in all directions, clearly there's more to "work" than just distance covered.

So, when it comes to effort we must talk about force also and not just the displacement or the distance covered.

Now, work done is dot-product (think of it as regular multiplication with some added bells and whistles) of force and displacement. In our (slightly special) case the increased diameter/radius of the wheel implies that we need to exert more force to turn it (will edit n insert equations as soon as I learn MathJAX)

In plain english, big wheel implies more exertion to turn the wheel, even if we consider the wheel to be absolutely weightless.


Storing an inner tube I got a spare inner tube with my bike, which is good.

I checked how it was packed and found it was sticking somewhat when I pulled it out of the box, which I can only imagine is bad.

Would it be an idea to put someething on the tube for storage, talcum powder maybe?

I always carry a tube with me in my backpack on longer tours. I left it in the packet I bought it in, but only to protect it from being punctured by the other stuff I carry in the bag (eg a Leatherman and keys).

I doubt that this is necessary but with or without the carton, the tube fits perfectly at the bottom of my Camelback, and the bit of added weight doesn't freak me out, too.

There never was talkum on the tube, and it is a pretty expensive tube, so do not worry about that.

Talcum powder, baby powder even flour will keep it from sticking to other items or itself.

Long term storage you need to worry about the heat. if its older than a year i would worry about it dry rotting.


What's the strongest way to bond a cable stop to an aluminum frame? I recently picked up another well loved GT road bike frame- it's in great shape aside from a missing downtube cable stop. The model is a ZR 4000 probably from 1999, it's 7005 heat treated aluminum. My best guess is that the cable stop was originally glued or bonded to the frame somehow based on a lack TIG weld lines or braze. I'm not sure if the cable stop snapped off from poor storage or when the frame was in use last. It's a CL find and lived in a garage for a number of years.

What's the best way to reattach a new downtube stop? Would I have a stronger bond if the new cable stop was aluminum or plastic? I have a great work space with appropriate ventilation and equipment, but after preliminary research I've found a lot of aluminum specific products (like those used on airplanes) can't be purchased online or by individuals, so whatever product needs to be accessible in that regard.

I'm also open to non-adhesive/epoxy solutions, but the tubing is ovalized and very oversized, so using downtube shifter clamps doesn't seem feasible. As a last resort, would using a hose clamp be safe on ovalized, aluminum tubing once I got it tight enough to withstand the forces of shifting? As a last, last resort, I am prepared to run cable housing all the way from the brifter to the cable guides under the bottom bracket. I'd like a pretty bike, but ultimately this one is just for riding and not show.

Since you have a relatively "flat" spot there (at least flat in the longitudinal direction) you have two options:

You can epoxy on a replacement boss

I did this on a recent Al frame with the exact same problem. I bought a metal (steel) cable boss from the local bike builder and epoxied it myself. I used Loctite's Metal/Concrete epoxy since it's designed for:

machinery, appliances, tools, lawnmowers, automotive components, pipes, embedding bolts and screws into metals, concrete or stone and sealing electrical components against moisture and vibration

Although lots of other epoxies will probably work.

If you do this be sure to read the instructions on the epoxy, clean the surfaces on both parts, and create a good clamp for the piece. It'll take 24 hours to dry fully and you aren't going to achieve good results by holding it with your hands.

Once's it's dried be sure to test it by attaching whatever brake/derailleur the boss is for(in your case the rear derailleur) and running cable through it. You need to be sure that the epoxy will hold the forces that will actually be applied by the brake/derailleur** Don't expect your results to look pretty though.

you can rivet on an replacement boss

There are many options here depending on what type of cable stop you need.

You could easily do this your self but you'll likely end up with a rivet gun and a box of 100 rivets you'll never use again (on a bike at least).

Whatever method you chose, I'd suggest completing it before any of the rest of your bike build (I'm guessing from the missing front end that you're rebuilding this bike). If you can't get it fixed you might have to scrap (or at least rethink) the project and you don't want to waste any money on other parts until you know for sure.

Regarding welding:

Aside from the heat issue of welding aluminum, you'll also have a tough (impossible?) time finding someone who can weld a steel boss onto an aluminum frame. Or you'll have an impossible task of finding an aluminum boss to use instead. Think about it.. there's a reason the manufacture glued the boss on in the first place.

** Be extra careful if you are repairing a brake boss. It holds more force and obviously has more dire consequences if it breaks off again.

You can take it to a welding shop and they will be able to weld it.


Can you trim rim tape once installed? I installed my rim tape then noticed was too wide so I trimmed it with a razor knife. Would this have caused any damage to the rim bead?

Probably not, depends how careful you are and if they are carbon rims.

I always do a 3cm test to get the best width, then take my time and gracefully cut the width of the entire roll with a cutter.
Now you have a entire roll of the correct width and you just apply what you need.

You can though I can say that in 40+ years or riding and many years of working in shops I've never once had to do this. Rim tapes come in various widths from various makers so you should be able to find one that will fit. Also a little too wide is far preferable to a tape that is a little too narrow.


Why do current, entry-level shimano rear derailers have large-diameter pulleys? I have seen (and recently bought) entry-level rear derailers from Shimano (Tourney for MTB, 2300 for road bike), and I keep wondering why they are making these parts with such large pulleys.

I don't think this make the parts cheaper to produce, since large size means more material, and I can't see why customers would find this more attractive or adequate than the smaller-sized ones (unless customers would prefer more expensive models because they DON'T HAVE large pulleys...).

Also, I imagine there might be advantages to larger pulleys (less chain link rotation, less wear, slower pulley rotation), but the reason why entry-levels are big, while more expensive models continue to be the same old size, is very unclear to me, not to say arbitrary.

There are 2 versions of derailleurs which come with extra large pulleys.

The first, which is what is being discussed here, are the low end mega-range compatible derailleurs.  A mega-range freewheel has one distinct characteristic which requires compatible derailleurs to have very large cogs.

As seen in the image below, there is a large tooth count difference between the second to largest cog and the largest cog.

This large difference in size requires a large derailleur pulley, to make sure that the chain has cleared the teeth on the last cog, in order to shift into this gear.

If you use a smaller pulley on the derailleur, you may be able to get it to shift, but it will be clunky and loud at best.  At worst, it will trap the chain against the side of the largest cog, and refuse to shift into that gear at all.

The second type of large pulley derailleur is decidedly not low end.

The Berner Carbon Fiber derailleur upgrades are designed to reduce resistance on the drive-train by decreasing the severe chain bends associated with smaller cogs. While expensive, my experience has been an average 10 watt reduction in energy used by the cyclist, with no apparent loss of efficiency in shifting, or in anything else other than the cyclist's wallet.

Smaller components need much finer machines (higher cost) to manufacture.  When precision scales up, so does cost of manufacture.  Larger items are easier to manufacture. When it comes to performance, apart from materials, there is often a large cost associated with the type of manufacturing process involved.


Rear light with failure warning It is a thing that I noticed even on cars it is missing: when rear lights fail, the driver does not realize it.

In bicycles it is much more worse it happens, as the cyclist's own life is more exposed.

I would like to know if someone knows about the existence of REAR lights for bicycles that give some feedback about their own failure, without the needing of
the cyclist to lift up from the bicycle.

My thanks in advance.

The problem is that you have to start considering the failure modes of the failure detection system. You're quite likely to end up with a less robust system or a lot of false alarms if you have a system designed to warn you of failure.

You also have to consider what faults would be detected:

a dead battery? You'd need another power source to feed your warning
a briefly open contact causing the light to switch off (I've had a proper brand light do this every pothole on a road bike)? Can this be distinguished from a deliberate switching off?
accidental switching (e.g. bumped by a pannier)? How is that different from switching it off?
unlikely failure modes like LED burnout? These shouldn't happen in a well-designed system, and I wouldn't trust failure detection in any other system.
the light falling off? Quite a likely failure mode but an extra fixing would be more reliable and less effort - and your failure warning service could fall off too.
Damage (which could be things like a failed connection or loss of focussing optics) due to vibration/fatigue/impact. My helmet-mounted rear light has lost an LED to this, and another flickers, so it happens.  With series-connected LEDs (common on e-bike rear lights) or a failure in a common electrical path, you could easily lose the whole output.

So instead we consider a system designed to confirm that the light is on. If the confirmation fails you stop and check. This could be a design or mounting that deliberately directs a little of the light to where you can see it. Simply mounting your rear light on your seat tube and having a silver-coloured pannier rack is an easy solution to this. A light with some front-facing white/yellow lights that shine between your legs would cost battery power but might increase visibility.

There are big advantages to multiple independent lights:

you're more visible from more angles (and further away if you add lights up high)
approaching vehicles can get an idea of how fast they're gaining on you (this really needs multiple constant lights to work well)
they indicate your size better - important if you're wider than a driver might expect (trailer for example)
and of course the big one here: if one dies you've still got some minimum level of lighting at the back.

I take this approach with two steady rear lights and a flashing one on my helmet (also with yellow LEDs on the sides). Sometimes I have a third rear light as I have one on the top of my daughter's seat and one on my spare pannier.

Another consideration is what you'd do if you detected a failure and it wasn't easy to fix at the side of the road, an hour from home, in complete darkness.  With a backup light or two, just ride on.  Of course this does mean you should check your lights at home - this is just a matter of looking at them as you switch them off and not doing it by feel.

The previous suggestions have all been good but I'd like to mention that I've had a decent amount of use out of one of these http://www.wiggle.co.uk/lezyne-macro-drive-duo/

You can strap it to the top of your helmet and the light points where you are looking which is good for forward vision but it has a red light on the back which flashes. It's foolproof to know whether it's on or not.


Cracking/Creaking noise when pedalling hard or standing on a pedal So my 1 month old bike started making a creaking/cracking noise when I pedal hard or stand on a pedal. For example if I only pedal hard on one side and just let the other side spin its fine but as soon as i paddle with both sides it creaks on every stroke.
Since I'm short on tools I've only tried new pedals, taking of the cranks and put them back on with grease, took the chain of and just stood on one pedal then switched to the other one and the noise still appeared. Took out of seat post and checked every bolt/axle/quick release on the bike except the BB. It seems to be a sealed shimano cartridge so is there a way to "fix" it, do I buy a new one since while I'm already at it or can it be something else?
It´s a Fuji Nevada 1.9 29 2021

From what I can tell its threaded, looks similar to this one:

Where did you buy it? I'm guessing that your local bike store, unless they were the place where you purchased it, probably has little if any interest in working on the bike, unless you are willing to pay a good amount.
I looked at the specs on this bike and the crank/bottom bracket is not precisely described. Pictures would be helpful, but if the bottom bracket has cups that attach it-- the manufacturer only seems to sell that kind-- my guess would be, you need to remove the cups, put some anti-seize compound on the threads, and torque them down properly.
I had a creak like this on my bike, which was assembled in Taiwan, and upon disassembly, found the BB cups were barely lubricated with a minuscule amount of some all-purpose grease. I put in a proper amount of anti-seize compound, reassembled to spec, and all was well, no more creak.

There can be a number of creak sources. Let me share my example.
I bought a bike with 28-spoke wheels. (Normally, I would not purchase a bike with anything less than 36 spokes per wheel, but unfortunately it has become hard to find bicycles with reasonable spoke count.)
Needless to say, the wheels lost spoke tension after riding a while. The front wheel lost all of its tension on all spokes, and the rear wheel only partially lost tension.
My solution for this was two-fold:

I made a plan to build myself replacement 36-spoke wheels so that I can have wheels that won't fail
I asked the bike shop where I purchased the bike from to fix the existing wheels

The "solution" of the bike shop was to put thread glue into every spoke nipple, and to slightly tighten the spokes. After I got the bike back, I rode it for 700 km or so with the "fixed" wheels before building my own wheelset. Upon carefully inspecting the "fixed" wheels, spoke tension on the average was low, wildly fluctuating (so not equivalent on every spoke) and it appeared what kept the spoke nipples from unscrewing was the thread glue.
The spokes on the "fixed" wheelset didn't unscrew anymore due to the thread glue, but a different problem developed on the rear wheel. When riding hard uphill, there was a mysterious creak. I originally assumed the creak would come from a bent rear wheel axle, but now I assume the creak actually came from the spokes, some of which still had inadequate tension.
My replacement rear wheel that I myself built with DT Swiss TK 540 rim, DT Swiss Alpine III spokes, DT Swiss Pro Head brass nipples, and Shimano FH-R7070 hub, did not suffer from the problem at all. Obviously I did not use any thread glue, put enough tension on all spokes, ensured the spoke tensions were equal, stress relieved the wheel carefully in addition to ensuring the wheel is true.
Of course it's theoretically possible that the original rear wheel having a cheap non-Shimano "Formula" hub could have something broken, but I believe it is a plausible theory that the rear wheel spokes are creaking when riding uphill.


Front disc brake wobbling / grinding on pads after full braking and minor plunge The front disc brake grinds after a light accident with full braking and plunge.

To give an idea of the forces involved:

The bike fell to the left, mostly cushioned by me. The bike had no more linear
momentum. The brake lever and handlebar band has minor scratches. The handlebar
or stem is slightly skewed.

It look like the wheel/rim is not deformed/buckled, it's not visibly
wobbling.
The disc is slightly deformed, wobbling at most a couple of 100µm. The
bending cause by the pads looks more than a millimeter.
The gaps between disc brake pads are not even, one pad is always touching
the disc. The disc seems to be not centered in the brake.
The handlebar is slightly skewed (de-justified stem/steer tube).

The animation shows the brake photographed from the front toggling with brake
released and slightly, but not fully pressed:

From the animation you can see that the brake pads are not evenly spaced. On the
left (inner) side there's a (wide) gap, while on the right (outer) side the pad
is already touching the disc. Also, the disc is being pushed and bent by the
outer pad moving.

(Note that the animation was created from two photos taken with the bike
standing but being unfixated and the levers being operated. This causes some
minor movement of the whole bike. If you think this makes the judgement
impossible, tell me and I'll try to make a better pair of pictures.)

The animation shows the wheel spinning in 90° steps, photographed with sharp
angle to (along) the fork:

The wobbling is quite visible.

There's no more than these scratches caused by the plunge:

Technical data

Gravel bike
Carbon fork
Through-axle
Aluminium drop bar
Shimano 105 BR-R7070 with dual pistons
1200 km driven, 4 months old
Bike: 10 kg
Saddle bag and water bottle: 3 kg
Me including backpack: 65 kg

Course of events

This is after full braking and a - presumably - light plunge from standing. The
front wheel locked, the rear wheel lifted off the ground. The bike was upside
down (angled 45° - 90°) and I had the saddle in my spine before I fell fore- and
sidewards.

So I pushed downwards and sidewards (along the axle, not in driving direction)
into the stem with my body weight and a bit remaining momentum. There probably
was torque by the fork into the axle.

Questions and guidance

Is is possible that the braking energy itself might have

deformed the brake?
deformed the disc?
damaged the wheel hub?
deformed/invisibly fractured the carbon fork?

I'm pretty sure the bike pluging did no major damage.

What was stressed most during braking?

What components shall I replace (apart from re-justifying) to be safe?

Apart from asking a professional bicycle technican for an estimate, are there
things I can check for myself?

Might the fork be damaged by the aforementioned forces?

More background

This happened during a light traffic accident.

Ask for details

Ask for details, more part numbers, measurements or other photos (i.e. of the
scratches) if required to gauge this. If you think there's too much distracting
information, tell me and I'll remove it.

History of later clarifications/additions:

Clarified: double pistons. Rephrased/deduplicated "Course of events" section.

Two possibilities - the wheel itself have shifted, unlikely with a though axle though.  The crash does not seem to have be bad enough for a major damage like deformed hub to damaged carbon fork (Carbon is far tougher than many people make out and tends to fail catastrophically). However, if you have concerns over the fork,  get it checked by a bike shop.  While the risk of damage might be slim, the consequences if the fork fails are about as bad as it gets.

Its likely that the caliper has taken a knock and shifted on its mounts. All that will be required if this is the case is aligning the caliper.  Refer Park tools website for detailed instructions  https://www.parktool.com/blog/repair-help/hydraulic-disc-brake-alignment

The short version is to loosen the caliper bolts, apply the brakes gently hile spinning the shell, as you tighten the bolts slowly and carefully. This will center the caliper and and alight the pads with the disk.

That rotor is warped. This is a sign that it got too hot. Replace the disk. It sounds like you came within a hair's breadth of serious injury. If it was me, every time I used that brake I would be wondering if this was the time the rotor would fail. Every little noise or vibration would eat at me. You needed every bit of brake performance you had, and that will never be as good or as reliable as it was before until you fix the damage. If the pads are replaceable do them too. Your safety and peace of mind is worth it.


Puncture in tube with sealant Had a thorn in my tyre last night, the tube has sealant in it, which worked.
How long is it likely to last, or should I change/repair the tube as soon as possible.
28 mm almost slick tyres running with 110 psi.

To clarify, the tyre has an innertube that came with sealant already inside the tube. I removed the thorn and the hole sealed, it is still holding pressure. The recommended pressure for the tyre is up to 120 psi.

Hypothetically yes, it will last a while - if a sealant is used in a tube and the tire subsequently gets a puncture, you must remove the penetrating object or it will flex in the tire, continually un-sealing the hole and shredding the tube.

If you believe you completely removed whatever caused the puncture and the sealant plugged the hole and you were able to continue your ride, that's great!

Some steps to further make sure the sealant will hold for future use:

If significant sealant was lost during the puncture and you have a removable valve core, add more sealant.
If you are truly concerned if the tube will stay plugged you can add glitter through the valve core. This helps plug holes, especially depending on the type of sealant you are using.
Reattach the valve core and inflate the tire.
Spin the wheel to mimic the motion of rolling down the road.

Given enough time, most sealants cease to be active and should be cleaned out; if they solidify, they unbalance the tire with useless weight concentrated in a single spot. On a tire with an inner tube, including a tubular, you’ll need to remove the sealant through the valve, which requires removing the valve core, and ideally rinsing and sucking it out. That is a lot of work if it is a tube in a clincher wheel. So you could always deflate the tire, remove the tube and insert a brand new tube and repeat the steps listed above.

The answer to your question is that, if it's leaking air, it can last a little while, but I believe you should have it repaired as soon as possible. I don't have tubeless tires but I have done a ton of research on the matter. There are some kits around to help you if you are new to the subject. Generally, if you think that is is not leaking any air then you are very lucky my friend and do not need to pay any attention.


Why are spoke nipples called nipples? Does anyone know the etymology of the term 'spoke nipple'? The wiki page on Spoke Nipple and even google doesn't have the answer.

Are there other threaded mechanical screws that are more like 'nipples'? Or did the end of spoked wheels at one point resemble nipples (say, for wooden wheels)? Why are they called 'nipples'?

In plumbing and piping, a nipple is a fitting, consisting of a short piece of pipe, usually provided with a male pipe thread at each end, for connecting two other fittings.

  - http://en.wikipedia.org/wiki/Nipple_%28plumbing%29

This is from the wikipedia entry on the plumbing and piping context of the word Nipple as suggested by Daniel R. Hicks' comment.

Can anyone elaborate on the etymology of this, or why this term for short pieces of pipe was used for spoke ends (perhaps proper piping nipples were used in the past)?

Nipple. It's just a fun word used to describe 'protrusion'. Something that 'pokes' or 'sticks' out. A 'nipple' was a nipple before it was a body part. I believe a woman's 'nipple' have been called many things before people got used to the fact it was just an average body part all humans have (men included).
That said, to demystify the word "nipple" & bring it's truth to light, look around and see just how many things actually have a 'protrusion' of some sort and consider it might have been called a nipple before it was named something else. Like, an "outty belly button" ...isn't that just a stomach nipple?


How to get a broken torx bit out of a bleed screw? In the latest episode of my disastrous bike maintenance attempts, I got a sub-standard torx bit that broke off in the bleed screw of my Tektro Vela disc brake caliper.

Here's a sligthly overexposed picture of the brake caliper in question, the bleed screw is circled in red:

And another shot from the side. Notice how the bleed port is recessed rather than the bleed nipple you'd usually see on a Tektro brake.

Considering that the screw is slightly recessed into a somewhat expensive safety device, I'd like to find out a way to get the bit out in the least destructive way. If all else fails, I'm considering eating crow and taking my bike to the LBS in the hope that they'll have the tools, experience and/or spare parts to fix this.

From the photo you posted reasonable option is to drill a hole in the bit and use drill extractor, spinning it anti-clockwise.

Bit is made of hardened CrV steel, so drilling it may be hard, since it should be precise and centered. If you feel unsure about your skills, give it to professionals, to locksmith or to your local bike service. It may appear cheaper, since damaging caliper housing would be much more expensive than spending some extra euros to have it fixed.

Depending on how stuck it is you may be able to pull it out with super-glue on the end of a stick. Use a "helping hands" tool to hold it while it sets.


How do I reduce slack in the chain of a single-speed bicycle? I have a single speed bicycle that has some slack in the chain and threatens to come off.  How can I reduce this slack?

If you have horizontal dropouts (the wheel axle slides into the frame from the back of the bike) the dropouts have long slots which will allow you to pull the rear wheel back and take slack from the chain.  Be careful to ensure when you torque the wheel nuts down the wheel doesn't slip from being aligned straight, or the chain is running at a slight angle.

If the chain is so stretched to the point where it's falling off, you really should consider replacing the chain.  You can get away with removing a link to remove the slack but a worn chain will be prone to sticky links and popping off unannounced.

Your chain has probably stretched.

An amusing anecdote.  I took my 1996 Litespeed Tachyon (20K miles or more on it) into the shop for a tuneup and asked them NOT to change the drive train unless absolutely neccasary, since it would mean changing everything.  Its DuraAce so that would be a big chunk of change.

Anyway, turns out my chain had stretched a complete link!  It was clearly stretched, but one complete chain link, so he popped out a link and reconnected the chain.

Short of that you will have to decide what you want to do.  See if the chain is stretched.  They have a tool for this, see if you can borrow one.


How much resistance comes from each part of a bicycle? How does one decide which part of a bicycle is the best candidate to upgrade or tune if the goal is higher speed for the same energy? For example, should one upgrade wheels, or tyres, or change to lighter parts, or to reduce aerodynamic drag with fairings?

Is there any way to compare the influence of each part? How much power can you save, and is it significant enough that you can recognize the difference? For example, do aero improvements make sense if speeds are very low and, if not, how can you determine the speed above which it does make sense?

We are reinventing wheel here.
Aero formulas from Sheldon Brown and racing bike chart

Few similar links answering this question:
- resistance types

- aerodynamics part 1

- aero (exploratorium.edu)

- human body front area depending on pose in case it will be possible to ride in horizontal position drag must be way smaller as front area will be at least 5x smaller.

Answer: This question cannot be answered in a simple tabular format because the resistance of every part depends on every other part.

IE, a wheel and tyre and spokes will have an effective "cross section" which is the hole it has to punch through the air.

That area is mitigated by the shape's curves.  From wikipedia:

So for simple shapes in isolation, the drag coefficient is known, and you can measure the cross sectional area in square metres.

Your problem is that a bicycle is not a sphere or anything simple - its a complex series of parts and they're hitting the air at different delays.  So when the air hits your downtube, its already been distrupted by the front wheel, forks, and headtube, as well as being in close proximity to your shin which is a periodic displacement of air.

To approach what you're asking - you'll need either to buy time in a wind tunnel, or fit a power meter on your bike and measure your times.

Doing this with scientific rigour means

doing each run at least 3 times
riding to a set power that you personally can maintain for the whole distance - no more and no less.
riding a distance of at least 30 minutes
having a route with no chance of stopping at traffic lights or similar
in an environment with consistent winds/temperatures/humidity across all your trials
and having a way of measuring your time as accurately as possible between a well defined start and stop point.

Then swap the one part you're testing for the other part, and repeat the three runs.

The difference in time will show you how much power you've saved/lost with the one variance.    If you want to test 5 types of pedals, that's 15 runs.

A circular route will help too, if you can find one that works for all the above requirements.

Ideally your rider would not know which parts are being tested on each run, so they can not be swayed to push harder or softer subconsciously.

One might reasonably assume that Manufacturers would release this kind of data, especially for their high-end items.   And they do with statements like "saves 17 seconds in a 40 km time trial, over last year's model."  Which is relatively useless as a comparison.

tl:dr - there's too much interdependence to make a simple table that is also accurate.

Edit - tables using same values as example below - 180cm/80kg rider, 15kg bike, hands on the tops bike

- narrow racing tyre:
Aproximate power formula P = (0.875492969 * v) + (v3 / 150.37973)
for > 20km/h max error 3.5% / avg error 1.046% (rolling + air)

Share (%)

Speed (km/h)         11     15     20     25
Rolling resistance 49,82  35,42  23,91  16,91%
Air resistance     50,01  64,42  75,94  82,97%

Power needed (W)

Speed (km/h)        11     15     20      25
Rolling resistance 9,63  13,13  17,51   21,89 W
Air resistance     9,67  23,89  55,62  107,43 W
Total power       19,33  37,09  73,23  129,48 W

- robust wide touring tire (%)

Speed (km/h)         11     15     20     25
Rolling resistance 60,15  45,44  32,30  23,59%
Air resistance     39,85  54,56  67,70  76,41%

Speed (km/h)         11     15     20      25
Rolling resistance 14,59  19,90  26,53   33,17 W
Air resistance      9,67  23,89  55,62  107,43 W
Total power        24,26  43,79  82,15  140,60 W

In Michael's link rolling resistance formula is computed this way:

CrEff = LoadV[Bike#] * CCrV[Bike#] * CrV + (1.0 - LoadV[Bike#]) * CrH
(Rolling drag coefficients:
Cr front (w/o wheeldiameter correction): CrV
Cr rear: CrH)

Frg = 9.81 * weight * (CrEff * cos(Slope) + sin(Slope))

P = Cm[bike#] * V * (... + Frg)

Power loss of tyres, flat:
P = Cm[bike#] * V * 9.81 * weight * CrEff

Example 80kg rider, 15kg bike, narrow racing tyre (Cm = 1,025 - hands on the tops):
P = v * 0,8756446875 (W; km/h)
(24,32% of 72W share @20km/h)

or

P = v * 1,326734375 for robust wide touring tires (thread)
(29,48% of 90W share @20km/h)

Power ratio between narrow and worst resistance tyres in example from that form is 25% (72/90W).

Tyre description                       Cr
narrow racing tire (high pressure)     0.0033
medium-wide high pressure slick        0.0031
wide high pressure slick               0.0029
robust wide touring tire (thread)      0.0050
Rinkowsky radial ply tire (wide slick) 0.0016
offroad tire 1.75"                     0.0046

Bike# + description                                       LoadV CCrV
0  Roadster                                               0.33  1
1  MTB                                                    0.45  1
2  Tandem                                                 0.5   1
3  hands on the tops (top of handlebar)                   0.4   1
4  hands on the drops (bottom of handlebar)               0.45  1
5  Triathlon Bicycle                                      0.47  1
6  Superman Position                                      0.48  1
7  Tandem with racing bars                                0.32  1.25
8  LongWheelBase under seat steering, commuting equipped  0.55  1.25
9  ShortWheelBase under seat steering, commuting equipped 0.55  1.25
10 Lowracer above seat steering Kreuzotter race           0.63  1.25
11 Streamlining tailbox Kreuzotter race                   0.63  1.25
12 Streamlined Lowracer White Hawk                        0.55  1.25
13 Streamlined Trike Quest                                0.72  1.5
14 Handbike 3 wheel                                       0.5   1.5

Do not like public lies - here is one example:

LaFerrari (400km/h top speed) could be overtaken by Peel P50 (45km/h), but do not take it seriously - one went out of petrol or was parking probably ;-)
Anyway one can pay 3x more for top wider to beat worst narrow (by resistance) if he feel physics or material limits are misleading.


Is it better to have mountain bike tyres for the winter? I have a hybrid commuter bike that is more at the mountain bike end of the spectrum

Currently I have slick road tyres on it.

Is it a good idea to get mountain bike tyres on it to deal with the wet and icey winter conditions?

I've heard conflicting stories about if they help or not

EDIT: To clarify - this is for commuting to work on the road. Not for off-road stuff.

It depends on your anticipated conditions.  If you're planning on off-roading in snow you need tires with fairly heavy lugs (though too heavy will just collect snow).  For ice you definitely need metal-studded tires -- riding a bike on ice otherwise is like riding on grease.

If you ride mostly on roads that are fairly heavily traveled by autos the best choice is fairly smooth studded tires where the studs are on the sides but the middle is smooth.  This way the studs engage when you lean at all, but don't seriously impede you when riding straight.

icebike.org has kind of fallen into disuse (the latest "news" is from 2006), but still has some good links.

Why not?

Tires are for bikes what shoes are to people.

You don't go to every kind of activity always with the same pair of shoes, so with bikes it shouldn't be different.

I think everyone should have enough tire sets to cover all the spectrum of terrains one regularly rides on.


Does anyone recognize this titanium frame? I bought this titanium frame some time ago. No markings, only the serial number on the bottom bracket. The 84 probably stands for 1984 as the bike was fitted with Campy's 50th Anniversary gruppo. The BB is Italian threaded.
Any ideas?

This frame has some features in common with this Fracesco Moser frame I saw. But there are differences, as well: the chainstays, and the fork.

This purports to be a 1984 Moser:

https://www.pinterest.com/pin/211950726189306619/?lp=true

Looks pretty much identical to the OP's frame.


Don't integrated headsets wear out, ruining the frame? I came upon this marvelous explanation of headset types.

However, this got me wondering. Isn't the role of the headset cups similar to that of the derauler hanged - to not waste the frame as soon as some wear-outable components ends it's life? How do frames with integrated headsets survive more than several years?

from forums.mtbr.com

Here's an excerpt from Chris King about headset types:

  What is an “Integrated” headset?

  It is a bicycle frame, fork and bearing system designed to eliminate the humble headset cup. To integrate
  means to combine and hopefully to simplify. What has been “integrated” by the integrated headset? The bearings
  now rest inside the frame instead of inside pressed-in cups. All of this trouble and confusion is to remove two 12
  gram headset cups from the front of your bicycle. True, an integrated headset can give the bike a nice, smooth
  looking front end, but the consequences of this change to your bicycle are significant.

  Simply put, the performance
  and lifetime that you expect from your new bicycle will be reduced, most severely in aluminum mountain bikes. All
  bicycle frames that use integrated headsets will ultimately have substantial performance and reliability problems
  due to the inherent flaws in this design. The largest flaw is a bearing system that does not positively attach the
  bearing to the frame, leaving the bearing to “float” resulting in wear and impact damage to the frame.

  As an
  additional complication, each manufacturer seems to be doing their own thing, with no real standardization to date.
  As a result, there are multiple bearing types and sizes (some of which have been discontinued with no replacement
  options) and the frame builders and bearing makers are not all working from the same drawings. Lack of
  standardization is a bad thing for everyone. It means that you may not be able to get replacement headset bearings
  for your bike, and you
  will
  need them.

So, to answer your question, yes, an integrated headset will eventually wear out, but that service time is dependent on riding type, style, number of hours, and quality/material of the frame.

You can read more about all three types: Integrated Headsets Explained

The image is wrong when it says you don't need special tools. There are special tools for both the installation and removal of integrated and internal headsets.

My point is that they are removable and replaceable. Having one wear out doesn't ruin the usefulness of a frame.


Fix up old road bike or buy new one? Coming back to riding after a long layoff, my Cannondale R500, purchased around 2000, according to the local bike shop, needs a lot of work - new wheels, cassette, chain, cables. Also replaced stem with a new taller one so I don't have to bend down as low.

LBS is saying the tune-up/restoration will be around 400 and offered a new entry level Giant for around 650 and won't charge me for the work they've already done on the old bike.

Not sure what to do. The Cannondale rides fine to me, but to be honest, I haven't put that much mileage on it recently so haven't really tested it. I'm a casual rider, planning to do long rides 3-4 times a month and a century or two this year.

My options are:

1 - Pay for whatever work they did and fix the bike up myself. Don't have a lot of tools and wondering if I did do my own work, I'd wind up wasting a lot of time and paying for tools I don't have.

2 - Have bike shop restore Cannondale, hope it holds up.

3 - Buy new bike.

I don't need a great bike, not picky, don't need the latest and greatest - just want something that will be maintenance free-ish for the next 10-15 years. I can afford a new bike, but I rather use the money for other things. And it just seems like a waste to abandon the Cannondale.

Any suggestions? Thanks in advance.

If you are coming back from a long layoff, I'd fix the Cannondale, then if you keep up riding in the future, spend some time considering if you want to upgrade and what to. It's never a good idea to be choosing a new bike under pressure to get riding.

Make sure the things the repair shop wants to replace are really needed. Cables and housings - yes that's a good idea and relatively inexpensive, but you could do that yourself.

Chain and cassette - make the shop prove they are worn out to the point of needing replacement. If not ride them until the do.

Definitely get the shop to explain why exactly they want to replace the wheels, and what they want to replace them with. You might be able to get a better deal on the used market through Craigslist or Ebay.

I spent over 300 pounds in parts to fix my Claud Butler 2007, 10500 miles, more than the price I paid for it new. I broke a shifter, which cost 80 pounds on its own, I changed the crankset, chain, cassette, one new and expensive Continental tyre, cables obviously and some cheap bearings for headset. After so much love, I retaped the steering and painted some scratches. Using it to commute in London, having a "sleeper" is great, sh** frame and brand, top wheels and components. Discreet. For sportives and recreational purpose, I would go for a new one. As for my renault, you build souvenirs and it is tough to get rid of it


Windows Phone as a Bike Computer - What is the current State of the Art? I have a Windows Lumia 532 phone.

I currently use the Cycle Tracks GPS app to track and record trips and then upload to Ride With GPS and/or Strava. There is not a native Strava app.

I've recently upgraded to Windows 10 making available the Gramin Connect Mobile app which will upload to the Connect powered by Garmin ecosystem. I've not yet fully investigated its capabilities/limitations. I've looked at buying the Garmin Edge 25 to act as a standalone bike computer, link to Garmin Connect Mobile and then upload to Connect powered by Garmin.

Apart from this, How else can I collect Cadence and Heart Rate data? Specifically,

Are there other dedicated bike computers which interface with Windows Phone apps like Garmin Connect Mobile?
Which apps allow direct communication with which Cadence and Heart Rate sensors via bluetooth?
Can I get a ANT+ adapter to communicate with sensors via ANT+?

More generally, What are my best options regarding using my Windows Phone as a Bike Computer?
Considerations are:

Capabilities
Limitations
Costs
"Open-ness" ie Are you "locked-in" to one manufacturer?

Having considered between unsing my android phone as a bike computer and buying dedicated computer, I noticed some points that could serve you.

Using cell phone:

You need a bike mount to be able to look at the data while you ride,
moreso for navigation, and they are somehow bulky, just like a cell phone compared to the dedicated bike gps you mention.

Cell phone battery will drain quicker, specially with sensors attached.
Usually, phone GPS is usually not as good, and for instance, I don't think I can connect to GLONASS satellites from my phone (Russian satellites for extra gps accuracy).
Bluetooth only allows for one sensor connected, so if you want to link a heart rate band, you could not link a cadence sensor.
If you want to connect sensors via Ant+ your phone need to be able to receive the signal, which is not the common thing, or buy an ant+ receiver

Usually phone apps give their best stuff on payed premium plans.
Phone apps usually take a good while deciding you stopped, which means a big time increase when measuring city commutes with all red lights etc. This can be avoided with speed sensor

Using dedicated bike computer

There are less expensive units that can connect to a phone to use it as their gps sensor, while the unit serves as smaller cockpit display with ability to plug in more sensors (basically HR, cadence and (more accurate) speedometer), but they won't show navigation maps.
Deciding between bike computers is already very complicated. The main difference is if you need navigating maps your options are less, and the better you need your navigation (i e you plan on using the gps unit on touring bike expeditions) the more clear it is that you need a big screen unit with plenty of battery time and good maps.
If you really like strava you may consider some devices that show strava segments live, but keep in mind this needs strava premium membership.
I found out something about gps recording: some units will record more data points of your traject than other. This could affect shorter strava segment times :P, but looks like it's not a big deal otherwise.
Some units have barometric meters on them, offering  more accurate elevation gain
Some units can display a great amount of data on the same screen
Some units have several training features that could be useful

I don't like and it seems it's not welcomed to give product recommendation, but since you mentioned it, I bought the gps unit you looked at. Still haven't used its follow track feature, but I bought it because of that. If you are not interested in maps, probably the competitor polar m450 is a better choice. For some reason I don't like the scheme that goes "no gps bike computer with connection to phone for gps" but it doesn't look like a really bad idea and it is way cheaper. Since I wanted a christmas gift i didnt check the cell phone bike mount, but I would have given it a try.

Also, keep in mind that for the price of a gps bike unit you probably can get a new cell phone with bluetooth and ant+, look that it has a good gps and battery life over camera quality or memory for instance, look that it is not very big and use it as a dedicated unit, but that would require research effort, and just getting a bike gps is more convenient.

RideJournal runs on windows phones.

http://ridejournal.rosher.co.uk/

Supports bluetooth sensors - displays the readings for free
Interfaces to OneDrive in the free version
Interfaces with Google Drive/Dropbox/Strava/MapMyRide/SportTracks in the payware version

Downsides

You have to have a windows phone
Supports bluetooth sensors - Recording the output of the sensors costs.
The costs are only displayed in the windows store


Why aren't Tour de France riders going any faster? I was having a look at the average speeds of the winner of the Tour de France over the years on this page. To help things along I put the data into LibreOffice and produced a plot:

I put on the chart where clipless pedals came in, and I suppose the switch to carbon framed bicycles came in a few years after that (not sure exactly when). What really struck me though was that the average speeds really haven't changed much, especially in the last few years.

There was a big jump in the late 80's/early 90's, some of which could be attributed to the doping practices of the time, but not all of it. Doping of some form or another has been going on since the beginning of the TdF.

It seems really odd to me that given:

improved training
improved nutrition
improved technology

there is only roughly a 10% increase in speed since the 1960s and virtually none in the last decade.

Are we being defrauded by companies trying to sell us all sorts of products (carbon whatnots and sugary goo!)?

The simplest answer to your question is that 1) speeds have increased; but 2) speeds would have increased even more except Tour organizers have been consciously making the Tour harder in order to increase the drama, suspense, and entertainment value of the race. That makes comparisons of overall winner's speed quite complex when combined with normal variations in wind, weather, and team tactics during the race.

First, some historical background. Over time, the winner's average speed in the Tour has indeed increased, especially in the period of the early 1990's and some (including, for a famous example, Greg Lemond, himself a three-time winner of the Tour) have claimed that this is evidence of doping behavior in professional cycling. However, as one of the other answers showed, there is a strong relationship between distance and overall winner's speed. Here is a plot that shows that relationship in the post-WWII period through 2012:

The distance of the Tour has been decreasing due to the rules and regulations of the UCI (the Union Cycliste Internationale), which negotiated a limitation to the length of races and mandated certain numbers of rest days during the Tour with the Professional Riders' Association. From an historical perspective, these limitation were a response to charges that the difficulty of the Tour resulted in riders needing to dope simply to survive, and that by "easing" the stages and inserting rest days there would be less need to dope.

An effect of shorter stages (and higher speeds), perhaps paradoxically, is that race organizers have been increasing the difficulty of the stages; this is particularly noticeable in the other two "Grand Tours", the Giro d'Italia and the Vuelta a Espana but also applies to the Tour: the number and "spacing" of categorized climbs in the Tour has resulted in more difficulty overall. Each year, at the announcements of the routes for each of the Grand Tours, riders and analysts pronounce whether a particular parcours will be relatively difficult or relatively easy, and favoring either sprinters, time trialists, or climbers. That there is a still a strong relationship between length of the Tour and overall speed simply means that the organizers haven't completely compensated for the distance effect with increased difficulty.

And, although your question was not expressly about doping behavior in the pro peloton, a bit more must be said about that. The plot above shows a clear relationship between distance and speed but there is still a question about deviations (or the "residuals") from that relationship. That is, after removing the effect for the length of each Tour, what is the remaining trend in the winner's average speed? The plot below shows that trend with a dotted red line.

As you can see, the winners' average speeds in the 1970's and 1980's were below trend, while speeds in the 1960's, 1990's and 2000's were above the long-term trend. So, even if the long-term trend in speeds can mostly be explained by Tour length (the correlation between Tour length and winner's speed is about 0.8), some have pointed to this secondary effect in the residuals as further evidence of doping. However, there are two counter-arguments, one slightly weaker and one very much stronger. The weaker argument is based on the observation that the residuals are "double-peaked" and speeds in the 1960's were also higher than the trend, then dropped in the 1970's and 1980's. If doping were the simple explanation, one would have to explain the drop in the 1970's and 1980's, not just the rise in the 1990's and 2000's. However, the stronger argument is based on examining data from other races and comparing them to the Tour. If one were to examine the residuals from a similar plot of speed vs. distance for the Giro and Vuelta, one would see that the years when their speeds were above (or below) their own trend lines did not correspond with the same years for the Tour. That is, the speed residual for the Tour and the speed residuals for the Giro or Vuelta are not "synchronized." Thus, if doping behavior explained the reason why Tour speeds were higher than would be predicted from distance, then one would have to explain why doping behavior was different in the Tour and Giro (or Vuelta) in the same year, often with the same riders. Below I include a plot that shows the "residuals" from the Tour (that is, residuals from the regression of winner's average speed on Tour length) plotted against the same residuals for the Giro. This does not mean, of course, that there is no doping in either the Tour or the Giro -- it simply means that one cannot use average speeds as evidence of that doping. Conversely, it also means that one cannot use doping as an explanation for increased average speed. Taken together, it does support the evidence that race organizers's decisions about the routes is a main determinant of the average speed.

the race is a individual route every year . you would need distance ,incline angles, wind factors and get a base . then you would have to match each race with these factors . so if it was a longer distance you find areas that match the base until all wind incline and distance is used from each race are matched perfectly to the base . say 15 degrees incline so you would have to search each year to match this 15 degrees for the same distance and you use these times if they are faster or slower. as you will never tell by simple results