Why does a loose pedal destroy the crank threads? Can someone cite with sources the process by which a loose pedal pretty quickly destroys the crank arm threads necessitating a helicoil repair?

I'm interested in how the thread on the crankarm gets destroyed in these cases. Shouldn't the pedaling action tighten the pedal back onto the crank if Sheldon Brown is correct?

Once loose, the pedal spindle will describe a cone as the crank rotates. This concentrates force at certain points in the crank threads, leading to damage.

Top image shows the pedal spindle in the threaded hole in the crank. The threads are fully engaged and tightened, and forces are distributed. Note there is space between the male and female threads (somewhat exaggerated).

Bottom image show what what happens what the thread is loose. The spindle can move around in the threaded hole in response to changing pedaling forces, and forces get concentrated at the red dots.

The right pedal has a right hand thread, the left pedal has a left hand thread. They do NOT self tighten.  The self loosen. This decision to give pedal spindles this threading was done so that on a fixed gear, such as an Ordinary (Penny Farthing), you'd not break your ankles if your pedal bearings seized.  They'd simply unscrew. Yea, and pigs fly.

Tighten up your pedals firmly, check them regularly and helicoils shouldn't be your crank's fate.


Bullhorn handlebars or extension grips? I use my hybrid bike for commuting and casual trips, and comfort is important to me.  I am therefore looking to upgrade my handlebar to the bullhorn type, as this greatly increases comfort and reduces strain on my wrists. However, well-made handlebars can be quite costly, and I see that "extension grips" exist that can just be put on a regular handlebar.

Obviously the handlebars need to be trustworthy, and not be prone to "slip" as I put my weight on it. Can the less expensive extension grips do the job, or should I opt for a whole new handlebar? I value comfort and safety more than price, but if all else is equal, price triumphs, obviously. The kind of extension grips I am looking at are attached at the bottom of this question.

If I opted for a whole new handlebar, I would still need to get one of these ergonomic grips for the horn-part of the handlebar, as the handlebars sold seem to mostly just be the metal bar itself. So I am leaning toward just getting grips to equip on my current handlebar, provided that they last and are safe to use.

So, will such handlebar grips provide me with long and safe service, or is really a whole new handlebar the only way to go? Preferably I want something that can be re-used when I someday buy a new bike.

Source: http://www.chainreactioncycles.com/se/en/ergon-gp5-grips/rp-prod35359

I'd give the bar ends a try. They give you a hand position or two more depending on model, and they're relatively inexpensive. Plus, I've never had slippage with my Ergon GP3's -- the clamp mechanism is excellent.

With new bars, you have to make sure that the clamp diameter of the stem matches the bar's clamp diameter, and the grip area diameter matches the shifter + brake clamps. There are some that 23.8mm (mostly used for road bars) and others with 22.2 mm (mostly used for flat bars) for the grip area.

As for bullhorns being bare metal, you wrap them in bar tape, just like drop bars for the road.

I'd also play with other adjustments on the bike, such as saddle position, bar height and stuff (an adjustable stem or quill stem if you have one makes this easy). You may be riding in a bad position or something which is causing the discomfort.

If comfort is your main goal go the grip extensions. Bullhorn bars are not designed for comfort. They are mean to give the rider a more aerodynamic riding profile to increase speed. That's one of the reason they are so popular in tri racing bikes.


How do I make a mountain bike go faster (commuting) I just began biking around 4 months ago, and due to lack of experience I bought a Diadora Orbita Mountain Bike. I've staring commuting to work recently (about 14 km daily) but I'm not exactly happy with my speed (around 17 kmph with no traffic) that is after inflating my tire and cleaning the chains on regular basis... Would changing the tires into thinner ones make my any bike faster? Are there any other modifications that I can apply to my bike to make it go faster? Or would be easier to just buy a road bike instead?

 (generic image)

I started commuting the same way about 8 months ago on a 29'er mountain bike, 2 things made the trip faster and more enjoyable.

Firstly tyres, I changed from knobblies to slicks and it made a BIG difference both in feel and actual speed.

Secondly I got a lot stronger from biking every day.

I eventually got a lighter cheap touring bike which is faster, and better in many ways, but I still prefer the mountain bike for fun.

You can start by looking at your gear ratio and change your sprocket size.  Hit a local bike shop and they should be able to find a fit for your crank.  Usually they are universal to fit on any bike.


Is it normal to need to replace my brakes every few months? My journey to work has uphill and downhill segments in both directions (a fact I'm sure to share with my future grandkids one day). In two of these segments, I have to brake pretty hard to arrest my speed.
Despite having my brakes replaced recently, and despite having worked from home about 50% of the time and not using my bike as much, I am once again in the situation where maximum-effort braking is no longer enough to slow myself down to a stop on these slopes.
Is the need for regular new brakes something I should just accept? Or are there higher quality brakes available that I should ask the bike shop to install?
EDIT: I think the brakes are disc brakes. This is what they look like:

I am vaguely aware that on some brakes you can adjust something that allows you to tighten the remaining brake material against the disc, but I'm not sure how you'd do that.

That seems too frequent and perhaps something else is going on with respect to cable tension that is preventing you from applying maximum force through the brake assembly.
For instance, if you still have material left on the pad and just feel like when you pull the lever in all the way that you are not slowing, then perhaps there is too much slack in the cable in relation to the resting position of the lever.
On my bike, I can use my barrel adjuster to get the pads the right distance away from the rim such that I have very little play in the lever before the pads touch the rims. If you have more than 1-2mm between the pads and the rim, then that is too much space.
Hope that helps and for a frame of reference I have several thousand miles on my Shimano 105 brakes, but I don't have too many major descents where I am really pushing them.
---- Edited Due to Pic Posting-----
Yes you have disc brakes and with the rust on there, it looks like you potentially could have a caliper that is sticking. I assume the pads are worn to the backing material when you take them off correct? If so, most likely a caliper that is not releasing for some reason or another.
I only have experience on car disc brakes, so will let someone else comment regarding the bikes, but if you have a sticking caliper, replacement of it/faulty parts perhaps is best vs. eating through pads and eventually the disc.

Presuming rim brakes
Steep hills means more brake wear.  Fact of life. Where I used to live brake blocks lasted for ever.  Now I have to adjust every 50 miles.  Arghh!  Rim brakes might be badly adjusted in many ways of course but I'm assuming you have the appropriate spacer washers etc. to get a fairly 'flat' contact.  (It's fiddly, trial and error sometimes!)
I'm told you can get various toughnesses of brake blocks.  The trouble is you might end up wearing your rim at the expense of the rubber!
The DIY answer is a front disc.  Investigate retro-fitting.  Once you've tried discs you won't want rim brakes ever again.  So much more positive, reliable and long-lifed.
Footnote: If you ever cycle even 'on the flat' with no brakes then you'll know why saddles are traditionally brown.


How to avoid turning the spokes while tuning the wheel When I tried to practice tuning my wheels, I found my spokes turn with the nipples. I tried to drop some lubricant on on the nipples, but I had the bike for two years now and there are a lot of dust clog in it. So the lubricant doesn't help too much. What can I do in this situation?

When I build/maintain wheels, I specifically make an extra quarter-turn to the nipple and then quarter-turn backward to release the rotational tension. This was recommended by Sheldon Brown

Lubing the spoke can help, but if your spokes are rusted, you might as well replace them with the new ones.

Give it all a good clean then try some of this this


brake lever will not return My friend has a mountain bike that survived last years Queensland's floods (Australia, that is), but is all battered and bruised after not being ridden for a year. With my beginner's repair skills, I managed to make it almost roadworthy. The main problem now is the front brake lever: It will activate the brakes when pulled (and they work just fine) but the lever won't spring back into place when releasing it.

Any ideas as to why that might be? Is there some spring that has can be replaced or does the lever have to go altogether? I have applied some WD40 inside the lever as I noticed some rusty parts there, but it didn't do the trick.

Edit: I got some new cables and cable outers (cost me an arm and a leg here in Australia!), but it didn't do the trick. I dismantled the brake lever, only to see there is a spring inside the lever. (The spring resembles 2 circles of 5mm diameter with two 1mm vertical tips on either side. I presume that the tips serve to "hook" the lever & possible return it to position.)

This spring was rusty and fell apart when I tried to squeeze it. To conclude, since everything else is new, the issue is either: - This rusty spring that needs replacing, or - The 90o cable guide that was also rusty.

Some things to check and I'm assuming you're running V-brakes:

My first guess is that the brake cable inside the brake cable housing is sticking. Some light oil on the cable could help. (WD40 is a solvent, do not use it on cabling or chains and do not use it where you want to maintain lubrication on parts. Look for some light oil like TriFlow, or whatever your LBS sells.) If the brake cable does not travel smoothly, I would suggest a new brake cable.
If you unhook the brake cable at the front brake arms, the arms should travel smoothly and you should feel some spring action that will resist squeezing. If the brake arms have no spring to them, that's a problem.
With the brake cable unhooked, the brake hand lever should move freely. If it doesn't then oil it. Light oil should penetrate any rust, and that might take 20 minutes of sitting before it works in.

Keeping the brakes in good condition is worthwhile and important. If you don't feel confident about how they feel, seek some help. Having a front wheel misbehave can be quite dangerous. Best of luck!

I agree 100% with bike guy, the spring on the lever is there for a reason and that is to return the lever to is opening position. Replacing that spring is a little tricky but is cheaper than replacing the whole cable. Try it and leave a feedback to see who was right


Broken rear axle. Why does it happen and is it worth trying to repair? So I'm taking the time during the holidays to overhaul my commuter bike. The whole drivetrain was full of old oil, road salt and grime so I decided to take the whole thing apart starting with the back wheel. Once I got it off, I ended up with half of the rear axle in my hand and a bunch of ball bearings on the floor (I found them all eventually).

The bike has been in use for about 18 months, and there were no rust and plenty of lube inside the hub so I don't really think it's natural wear.

What could have caused the axle to break? My theory is that they pulled the nuts too tight when they built the bike.

More importantly, is this a "user serviceable part" or do I need to get it repaired/replace the wheel? Seems to me getting the ball bearings to stay in place while I insert the axle would be quite challenging.

Most of times the axle is broken when not accurately jumping with bike (the same is with obstacles on road like holes and speed bumps). Wheels with freewheel are more exposed to this because their bearings (i.e. the place where wheel touching the axle) far from the place where the bike touch the wheel, therefor it have more moment to brake the axle.
To the question about worth repair. The only available repair of this - is to put a new axle, that means it will be like a new wheel (if you do not have other problems in your wheel). If you going to replace the axle, examine the bearings cup if it have any deformation. If it have, in most cases the wheel must be replaces. Examine also the cones.

Rear bicycle axles are often over stressed. Every old ten speed that I took apart had a bent axle because when climbing or accelerating it is possible to create a bending moment that will exceed the yield strength of the steel. If the axle was broken in the center,between the bearings, it is more likely that the fault was not the loading but bad metallurgy.

Recycled steel often contains unwanted metals such as copper that makes the steel brittle. Because of the limited service and the location of the break, I would guess that the axle was made in China of old DeSotos.


Is there such thing as a freewheel that doesn't click? The clicking sound of the freewheel on my singlespeed when it's coasting is annoying for me, so I flipped over my back wheel and rode fixed for a few months in blissful silence.  But having to pedal all the time even when going downhill, over bumps and around corners, was probably even more annoying - so today I am flipping it back again to the freewheel.  Then I wondered, is there any such thing as a silent freewheel hub that I can buy?  If so, what's the search term I'm looking for?

As already said, Shimano used to manufacture Silient Clutch rear hub. But that has been stopped a few years ago, so if you manage to source one - you are lucky man.

I used to have one of them and it was truly silent. It was heavier than standard shimano LX hub, but it was silent and with instant engagement.

Also I used Chris King hubs. If you put a lot of grease in their mechanism - they also become silent.
Pretty much with most of the freewheels, if you put a lot of thick grease in them, you'll silent them for some time. Unless you ride Hope hubs -)

I've heard about Stealth hubs - they are claimed to be silent, but I never had a chance to try them out.

You might as well read this thread about silent hubs for further information.

I have on my Kona Unit 2013 the stock "Formula DC52" - it's very quiet.


What model of bike does Alicia Vikander use in Tomb Raider (2018)? Does anyone recognise this model of bike? It has some stickers/decals with fictional logos, but I couldn't find any brands/marks on the bike itself (more images):

Note: The fox tail and paint can are from a 'fox hunt' game/race in the film. See here.

Details original Bike used in the Tomb Raider movie 2018:  SE Bikes Tripel, Saddle Books Champion Standard B17, Vera Citywide tire - SE Bikes logo on the front of the frame -  handle grips purple - red pedal - Rear tire is possibly Kenda K-152. Kenda road tire in yellow.

details of bike

[![][9]][9]

I can assume that the bike was made specifically for the movie and you can not buy it for yourself. For most films, exclusive things are done.


Front brake only on a fixed-gear bike Is it considered safe-enough to only have a front-brake on a fixie in a urban area that has many hills?  I've been considering buying one, but I want to get some opinions before I move forward.

Yes. The front brake provides basically all of the stopping power in a bicycle, and recent tests in Bicycle Quarterly show that, in emergency stops, the distraction of attempting to use the rear brake may even increase stopping distance. Maximum bicycle braking power is achieved just before the bicycle starts to pitch over, as the rear wheel lifts off the ground. Once that occurs, it's trivial to lock the rear wheel with a brake or by using your legs on a fixed gear.

The main disadvantage of having a front brake only in extremely hilly situations is not being able to dissipate some of the thermal load of braking between both rims, so you risk overheating the front.

People saying that a rear brake is useless must not ride much. Fast, steep, technical descents are much faster with rear brake, as is tight urban commuting.. even on dry pavement.

I'd challenge anyone with no rear brake(fixed doesn't count) to a race anyday thru the city. I really couldn't see someone even staying with me for more than a few blocks. First couple 90deg turns at speed you will see how no rear brake performs.

Then throw some gravel or oily water into mix.. not even close.

To be clear, I DO consider a fixed wheel as being a good rear brake, I'm talking about no rear at all as some people seem to think would be adequate.


9-speed system to 11-speed drivetrain upgrade? I am currently upgrading my bike from a 9 speed to an 11 speed system.  I am currently using shimano 105 components and will continue to use them within the new system.  Current bike has a shimano 105 rear derailleur but does not specify if it is unique to a 9 speed system.  Will I need to buy a new rear derailleur?

This page has the best answer I've found so far

http://blog.artscyclery.com/science-behind-the-magic/science-behind-the-magic-drivetrain-compatibility/

Reading between the lines, the cable pulls from 9spd to 11spd are probably close enough, but the derailleur ratios are significantly different. 1.4 vs 1.7. This means
that the 11 spd indexing in your new shifters will not work correctly with your old
derailleur.

You won't need to replace your rear derailleur. Cable pull is determined by the shifters so if you're getting new 11 speed shifters you can use ANY rear mech as long as it has a long enough cage to accommodate the largest rear sprocket. For example i'm pretty sure that if you have a short cage rear mech you won't be able to run an 11-32 cassette. The rear mech has an infinite range of movement between the high and low stop screws so as long as they are adjusted properly you'll be fine. B-tension screw is what brings the cage in or out to accommodate the largest cog.

The reason for any problems in compatibility is that for 11 speed there are more cogs (11) packed into the space between the hub flange and the frame dropout so the spacing between cogs is narrower which means the chains need to be narrower and the shifters pull less cable with each click. But if you try and run a 9 speed chain and chainset the teeth are wider so the chain won't sit properly on the chainrings.

So in short you'll need a new chain and cassette and shifters but you can keep your front and rear mechs.


Approx age of my Vindec I have just bought an old Vindec Ventura, With 27x1 1/4 wheels 32x630 rims. It looks like a hybrid but wondering if it was a sports updated. Any one any gen at all on this modelCheers all.

Answer:: 80's road bike with modifications

I'm guessing its an 80s road bike that has had the drops, quill stem, shifters and brake levers swapped out for a flat bar from a more modern MTB.

That's a gorgeous steel lugged frame

No bottle mounts are in the frame, which is why a PO has fitted a strap-on bottle cage.

Frame pump mounts also went out before the 90s, as did the uselessly-short mudguards.

That rear light looks like its powered by D batteries. so will be heavy.  I'd swap it for a pair of efficient LEDs, for safety when riding at night, unless you're trying for a period bike.

The cranks are cotterless, so its no older than the 80s or that was also changed - there's a triple chainring, which may have been fitted with the MTB bars or may be original.

There may be more info in the rear cluster/cassette and the rear derailleur, and the brand/model of brake calipers.

If it runs okay then air up the tyres and ride it.  I'd suggest changing all four brake pads, and examine the tyres for deterioration.

If the tyres are getting iffy, consider replacing the whole wheel with a more common 700c aluminium rim.  Those 27" wheels look like chromed steel and wet weather braking is wishful thinking!  Downside of this is the brake calipers may no longer reach a slightly smaller wheel and may not have as much pressure under braking.

I got one of these for Christmas in 1967/8. Happy memories seeing this.


32-622 tire too small for 622x19 rim? I recently bought a Mavic A 319 rim with ETRO 622 x 19C and Schwalbe Marathon 28" tire with ETRO 32-622. Based on the tire sizing chart found at Sheldown Brown (https://www.sheldonbrown.com/tire-sizing.html) and the recommended tire width by Mavic of 28 to 47 mm, I thought that the 32mm would fit for sure. However, it requires enormous strength to pull the tire onto the rim. Much more than any tire that I have changed in the past. Because of the very tight fit, my tire was pulled down slightly on one side, making it run unevenly. To correct for this I had to pull and push on different parts of the tire to make it fit evenly. Also, something I never needed to do on a bike.

Is this expected, because the 32 are on the low end of the spectrum or did I read the numbers wrong?

You have the correct tires.

This does not have anything to do with tire width. The diameter determines whether tires will fit or not, unless there is a huge width mismatch. Rims and tires are both made to a tolerance, and you just happen to have an unusually large rim and small tire. I have had the opposite problem with some Schwalbe tires, they were so loose that they kept slipping off the rim when installing.

One word:  oven. :)

Twist the tire once to fold it into a double loop that will fit in the oven. Consider using a nylon “zip” tie or two to hold the tire from unfolding
Bake the tire at 200 degrees for ~30 minutes
Wear a pair of work gloves to remove the tire and install it on the rim.  (200 degrees won’t bake cookies, but it’s too toasty to handle while installing.)

It’s still not easy, but it’s definitely more pliable and easier then at room temperature.

-David


Are there any major drawbacks to using a track frame as a frame for a fixed-gear or single-speed commuter? I follow a few communities which have a lot of fixie and single-speed riders. Most of the riding discussed is commuting around the city, and often, riders will show off their new bikes, upgraded hardware, or will post photos of parts needing maintenance, seeking repair advice.

I've noticed that many of the bikes are in fact track bikes, based on the track fork-ends where one would normally find dropouts.

Does using a track frame for day-to-day city commuting have any drawbacks, either for the rider, or for the frame itself?

Real track bikes don't have brakes. You need brakes for commuting, especially in a city, and at least 2 independent braking systems. Not all frames and forks have brake mounts. You also won't have fender or rack mounts which are nice in wet weather.

Ergonomics and geometry can be an issue, given that track bikes tend to be a bit twitchy and aggressively positioned.

A lot of people use them in an urban environment, probably because of fashion and some sort of bike messenger fantasy.

The drawback of using a track bike are the same as the advantages of using a track bike.  It is how you look at it.  The two main "features" are:
No brakes
No gears
You can look at these as drawbacks but they are advantages in city riding. Less weight if you carry the bike up stairs this helps.
Less maintenance. If you depend on it to get you to work this is a big positive.
A fixed gear gives you more control in stop/go traffic and when moving at slower speeds where having to brake often is a nuisance.  Adjusting speed with your legs is more efficient and enjoyable.
More control in wet conditions.

It is not all fashion.


Can I buy handlebar tape in bulk I have a couple of commuter bikes with bullhorn handlebars. When I replace the tape on them, I always have heaps left over, since the bars are much shorter overall than standard drop bars. There's never enough to do both sides of the bar with a single roll though, so I end up throwing out a lot of tape.

Can I get tape in a continuous roll, rather than pre-cut sections? I assume workshops would buy their tape in longer lengths, but I can't find any sources for it.

I manage the workshop in one of the busier shops in the world.  There is not, to my knowledge, any way to obtain cork or neoprene bar tape which is not pre-cut to length.  Usually, in my experience, though, one roll is enough to do both sides of a bullhorn bar.

http://www.bikepedia.com/PA/Item.aspx?item=839737 i found this site after googling bar tape 36 yards- better value and less shady! this works out at about £69 so 6.90 a bar tape change? but i sure you can get it cheaper :)


How much runout is acceptable in a disc brake rotor? I'm trying to sort out pad dragging / noises in Avid BB-7 mechanical disc brakes and I'm wondering how much runout in the rotor is acceptable? Right now I have about 0.05 mm (measured with a Park DT-3i).

0.05mm is nothing. Stop worrying about it. As long as rotor does not make noise or drags extensively on the pads, you'll be fine.

Rotors change shape every time you ride: you apply breaks a little longer than couple seconds, rotor heats up and expands, then cools down and shrinks. On extended periods of braking rotors can heat up enough to burn your fingers when you touch it (done it myself unfortunately). And when this level of temperature change is applied all sorts of transformation happens to the level of warping/runout. So you can spend all the time in the world to make rotor as true as possible, then you go for a ride and it all changed and rotor is nothing like you've left is last time when you fiddled with it.

I usually replace my disk brake pads when I have 0.5 mm thickness. The reason I do that is because they can easily be smashed by the jaws to remove the braking material ( which will eventually fall apart ). After that it will result in a friction between the disk and the metal of the pads, which is very very bad.

I change the disk when it stops braking when I use a new disk brake pads. But for the thickness I should say that It depends how much are you loading them. As you say above disk with thickness of 0.05 mm is very hardcore ;).
You should really think of replacing that thin disk, because it can really surprise you when it breaks.


Improving metabolic efficiency I'm doing road cycling, on hills, over long distances.

Typically at the moment, I'll do two 30-40 mile evening rides in just under 2 hours. Generally either 50ft per mile climb or 100ft per mile climb. These are fine and even going straight from work, with just water, I'm fine energy wise.

However, Sunday's are long ride days, typically 5-8 hours of cycling over 70-100 miles, typically with 100ft per mile climb ratio or more.

I ride with a guy 5 years older than me with one year more cycling training.

However, he rarely needs to eat on the ride, and he'll manage with a few gels and his energy drink.

Whereas, I'll have chugged 1-2 litres of chocolate milk, four rounds of bread (in the form of peanut butter and jelly sandwiches), a (big) bag of minstrels (yeah, jelly babies are better, but, I loathe them). PLUS the energy drinks and gels.

I've always had 'issues' with blood sugar crashes if I don't eat enough on a regular day. I seem to burn it fast.

What can I do to help re-train my metabolism to work better?

Fitness wise, my RHR is around 54bpm, my MHR is 192 (based on highest garmin logged figure), my BMI is bang on 22. The guy I ride with has an RHR of 46, has peaked his MHR at 199 and is probably (though I've never asked) about right on his BMI too. So yes, the fact I can't hold pace with him is because he has an edge fitnesswise, but we have a 'system' of him not waiting for me when I start to drop on the hills, so he's still setting PRs, but still doesn't need to load the calories like me.

I'm aware that my body stores energy in the form of glycogen in my muscles, and it's this supply that is burned first, followed by converting fat to use or any fast carbs I take in. And I'm eating a good amount of carbs for storing up the energy. Saturday night is typically a big pasta trough and a big bowl of porridge before I ride. The guy I ride with on the other hand is gluten intolerant and not taking pains to carb load. And often turns up hung over too. Just to rub it in :)

My fitness is clearly improving, I'm constantly moving on my PRs etc, however, I'm just not getting more 'efficient'.

Which means I'm carrying more weight in food which won't help me keep the pace will it: ;-)

The problem is burning too much carbs/glycogen and not enough fat, since you body has an essentially unlimited supply of the latter.
How? One step is to eat more fat and less carbs. That trains your body to burn more fat. This article also suggests pushing your limits on how far you can go without eating, as a way to train your body to need less. Another point is that you burn more carbs (vs. fat) at higher levels of effort. Do enough training at low effort, and your body will get used to using fat. That's the idea behind Phil Maffetone's training philosophy.

As far as I know or heard about this...

Yes, chocolate is good for ATP production. That is, without having to store fat. But, chocolate doesn't need to contain sugar, ok? The original chocolate is naturally sweet.

Then, it is said that having always a bottle of water mixed with vinegar is great to recover strength as well as refreshing in heavy duty tasks. This is an old biker habit. Vinegar also replaces sugar at the creation of energy cell-cycle. But you shouldn't abuse with it. Just a little.

Also remember that breathing is an important part of the burning metabolism. So improve it's rhythm & frequency.


When to replace rear derailleurs What is the typical life cycle of mid-range rear derailleurs assuming no accidents? More precisely, what's the average mileage after which it's better to replace it rather than doing tuning all the time?

Derailleurs will last almost indefinitely. The jockey wheels will wear out in time (tens of thousands of km) but the rest of the mechanism shouldn't see significant wear.

I got 23,000 miles out of my rear derailleur. The sprocket inside the derailleur broke loose and while it still worked it needed replacement. My bike is in the shop and I hope to get it back tomorrow. The first local bike shop just today told me it needed replacement and I took it to a second shop to confirm this. Make sure you find a shop you trust because I was told the derailleur needed replacement three years ago by a shop owner who tried to con me. It DID not need replacement three years ago. If you are unsure of whether to trust your local bike shop take the bike to another shop for a second opinion. I found many shops to be dishonest.  (12-12-2018)


What is considered a good "safe biking distance" to bike to work? I'm curious about what is the maximum distance you can live from work so that it's a reasonable biking distance.

I am interested in biking about 30 minutes to work. It would be about 5 miles away. I have a heavy cruiser bicycle (Schwinn). It would be a leisurely ride.

A good safe biking distance is the distance that one can enjoy the bike ride to work, get there a few minutes early to clean up or shower and after work enjoy another bike ride home and still spare some time to spend with family/ loved ones/have a life besides work and the commute.

I limit my bike commute to about an hour each way.

I am interested in biking about 30 minutes to work. It would be about 5 miles away. I have a heavy cruiser bicycle (Schwinn). It would be a leisurely ride.

I had a 5-year break from cycling. Before accumulating 100km after the break, I made several >20km rides. The largest of these rides was 28km. Less than 2 hours.
Before the 5-year break, I regularly did 50km rides. Such a ride is 3 hours. However, I wouldn't advise doing 50km rides to work, as I only did one such ride per day. A 50 km one-way distance is 100km per day.
The reason why I enjoyed such long rides and could do a 28km ride after 5-hour break? It's three-fold:

My bike fit was excellent. My dimensions didn't grow or shrink during the 5-year break, so bike fit is still excellent.
The bike is a drop bar bike with handlebers at the saddle level.
The bike is fitted with narrow high performance slick tires.

Throw away your current bike if the distance grows to over 5 miles. I'm sure you're limited to 5 miles with a heavy cruiser bicycle. There are bicycles better than heavy cruiser bicycles, and with those better bicycles, a distance of 20 miles may be feasible.


Is it a good idea to get a narrower front tire and a wider rear tire on a road bike? I am currently running Continental Grand Prix S 4000 in 23-622 / 700x23C front and rear. I am about to buy a new set of tires for my road bike and am fancying a smaller tire for the front and a wider tire for the rear. Actually Continental offers such tires as a set (GP attack and GP Force). Also note, that Motorcycles usually have a wider rear tire to support quick acceleration but still have dual disk brakes in the front to maximize brake force.

I tend to ride fast in a traffic situation where the majority of bikes travels slower. So I am often underestimated and have to brake sharply. While panic braking my bike tends to pulling, which I have learned to manage. I suspect a wider tire to reduce pulling, by developing more grip in low load situations. The weight balance gets shifted to the front, when breaking sharply and therefore the front tire does not skid even with much break pressure. The back tire on the other hand does only carry little weight and skid with the same brake pressure applied.

I am also facing periodical flat tires with a frequency of 1 per 10 weeks or so on the rear tire. I suspect a wider tire to pick up fewer glass splinters, by reducing the pressure. The rear tire carries the main load while non-braked riding and a wider one distributes the force to a bigger surface area thus reducing the pressure.

Update

Thanks for all the input. Your answers have helped me a lot in finding my decision.

I'm currently running the Conti Attack/Force combo on my road bike. I have previously run both the GP 4000, and the Schwalbe Ultremo ZX on the same bike.

The concept behind the Attack/Force is that the slightly wider (24mm) rear tire will allow just a bit more comfort, and the slightly narrower front tire (22mm) will be a touch lighter with more reactive handling.

I feel a difference in comfort, but I can't say the handling was noticeably different. Of course, the GP 4000 was pretty stable to begin with, so maybe that's a good thing that I don't notice a change.

They do feel a bit more stable in a corner, and I feel like the rubber compound is a bit stickier. They say it's the same Black Chili compound used on the current GP 4000, so maybe that's psychological.

I can say that the comfort aspect is worthwhile, and there is nothing I have bad to say, so why not try them. A set (here, at least) is the same price as a set of GP 4000's. No loss, at least, and a bit of gain on the comfort side.

@DanielRHicks commented that you might need to worry about braking power or traction. I've had no issues with braking performance, and these are a pro peleton tire. I don't see any issue there. I've also had no issues with flats on the tires, but then, I didn't have with the GP 4000 either.

Wanting different widths front and rear prevents you from the most effective way of changing tires: when the rear is worn out, move the front one to the rear and put a new one on the front wheel. This way you always have the most reliable tire at the front, and you never have to replace a non-worn-out tire due to ageing.


How to keep my hydration pack tubes and valve from freezing? I like to ride with a hydration pack when I mountain bike in the winter since all sorts of nasty stuff gets tossed up at my bottles.  However, I've had issues with the tube or valve getting clogged due to the water inside freezing during rides in the low 20s Fahrenheit (roughly -5°C). It's really hard to deal with this issue while you're out in the woods.

Is there anything I can do to prevent this from freezing so quickly?

The trick is to blow the water back up the tube and into the reservoir right after you take a drink.  This will keep your tube and bite valve from freezing.  This works well even at below freezing temperatures when skiing.

But you can revert law of nature.

1 Few Of the Points to keep your water flowing in harsh environment

2 Fill your reservoir with warm (but not boiling) water, which will
   take longer to freeze.

3 Drink frequently (a sip every five minutes or so) to keep your water
   circulating.

4 Blow back into the drink tube after you take a sip. This will clear
   water from the narrowest parts of the reservoir (like the bite valve
   and tube), which are usually the first to freeze.

5 Keep your water supply close to your body by wearing your pack under
   your jacket and routing your drink tube under your arm or through
   your pit zip.

6 Our winter packs also feature insulated drinking tubes, and many of
   the smaller packs are designed to fit both under and over your
   jacket.

7  On overnight trips, sleep with your water to keep it from freezing
   overnight. Just lock your bite valve closed and then stuff your
   reservoir into the bottom of your sleeping bag


Tools and spares needed to repair a chain on the road I'm increasingly riding long-distance randonees/audaxes and I'm pretty confident I can fix most simple things which might go wrong with the bike. However, I've never done anything with a chain apart from clean it and would like to be prepared enough to be able to effect some kind of repair if it broke, even if I ended up single-speed.

I have an 11-speed Campagnolo Chorus chain. I'm considering getting this chain tool, but what spare pins or other kit would I need? I'd prefer not to carry a whole spare chain due to the weight and space.

Replacing your chain at regular intervals is by far the best maintenance money you can spend on a bike. Generally what goes wrong with a chain is a "stuck link" and
the chain tool you have can fix that. Either by slightly tweaking the pin to loosen the link or by taking the link out altogether. If you do need to take a link or two out, avoid attempting to use the big/big gears. Generally there is no reason to carry a complete spare chain, only enough stuff to remove a link or two
and put the chain back together.

Some chains require special replacement pins. Check with the manufacturer. Exactly what's required varies between 9,10,and 11 speed chains.

For chains that have quick links, the quick links can break. Carry a spare quick link. You can use this to make repairs quick and simple. You can have more than one quick link in a chain w/o problems.

For the new narrower chains, I am not confident about reseting existing pins using any chain tool that you can carry on a bike. This is why I only use chains that have a reusable quicklink.

I'd think about switching to a chain like this in your case. Makes any on road repairs much simpler. However, I don't know of any 11 spd chain links that are
reusable.

I've done a bit more reading on 11 spd chains and I would definitely add a few spare used master links to your kit. KMC makes them and from what I read the old school method of pushing the pin back in just not safe with the very thin plates used to get chains narrow enough for 11 spd. KMC claims their quick links will work with any 11 speed chain.

According to the web site that chain requires special tool and a unique set pin

Assembling and disassembling Campagnolo 11 speed chain

As I suggested in my comment I think you have your priorities wrong if you a looking to buy a chain tool for road repair before you have even changed the first chain.

As for measuring the chain and chain maintenance have you referred to the manual?

Manual

It specifically states all assembly and disassemble should be performed with the special tool.

The manual has instructions on how to measure stretch.

From what you read it is hard to measure.  Why would you not include the manual in your research?


How to choose the right Citi Bike? It's 2013, and bike sharing has finally made it to New York City. Of course, the branded cruisers aren't the most speedy bikes on the road. They weigh a whopping 45 pounds, and their third gear - their lowest gear - isn't nearly low enough, making pedaling down even a slight slope practically useless.

Still, you can get moving if you pedal furiously... and if you pick out the right bike.

During a test conducted by New York Magazine, bike messenger Danny Koniowski hit a top speed of 27.5 mph on a Citi Bike. He did so only after picking out a choice bike.

  After inspecting and rejecting the first two Citi Bikes he came across at a Citi Bike station on Canal Street near Sixth Avenue — one for having misaligned tires and the other for being, in Danny’s professional opinion, “a piece of shit” — our test-rider finally settled on a suitable specimen.

I squeeze the tires before I choose a bike, but what more should I do? How can I quickly inspect my next Citi Bike to make sure I've picked a well-tuned cruising machine? Or at the very least, a bike that's not "a piece of shit"?

Typically you would want to do an ABC Quick Check - the information below came originally from the League of American Bicyclists site.

A = air

Inflate tires to rated pressure as listed on the sidewall of the tire.
Use a pressure gauge to insure proper pressure.
Check for damage to tire tread and sidewall; replace if damaged.

B = brakes

Inspect pads for wear; replace is there is less than ¼" of pad left.
Check pad adjustment; make sure they do not rub tire or dive into spokes.
Check brake level travel; at least 1" between bar and lever when applied.

C = cranks, chain and cassette

Make sure that your crank bolts are tight; lube the threads only, nothing else.
Check your chain for wear; 12 links should measure no more than 12 1/8 inches.
If your chain skips on your cassette, you might need a new one or just an adjustment.
Note - most of these bikes use Nexus type internal hubs, so just a visual check of the chain and a quick test ride should let you know what the condition is.

Quick = quick releases

Hubs need to be tight in the frame; your quick release should engage at 90°.
Your hub quick release should point back to insure that nothing catches on it.
Inspect brake quick releases to insure that they have been re-engaged.

Check = check it over

Take a quick ride to check if derailleurs and brakes are working properly.
Inspect the bike for loose or broken parts; tighten, replace or fix them.
Pay extra attention to your bike during the first few miles of the ride.

Edit: The comments seem to indicate that some people think this list if overkill. However, take a step back and remember... You are picking out a bike that doesn't belong to you, that you don't maintain and that really you know nothing about. True, you probably aren't going to measure the chain, or have a pressure gauge in your pocket, but I would spend MORE time inspecting a citibike before I ride off than I would a bike of my own. I am certainly going to look fairly close to see if anything is loose, broken, or way out of adjustment, and the mnemonic ABC Quick Check is an easy way to remember what to look for.

https://katieflor.medium.com/how-to-pick-a-good-citi-bike-80e6752149b3
This article mentions 4 things to check for picking a right Citi Bike.


Padded saddle VS padded shorts Why do cyclists use padded shorts instead of padded saddle? It seems like putting padding on the saddle would be more optimal. Doubly so for triathlon.

Padded seats tend to have more padding than used at any given time. This pushes the other 'extra' padding into the soft tissues. This causes numbness and discomfort over time.

So slim hard seats are actually more comfortable over time, if they are the right size. You need to make sure your sit bones (ischial tuberosity) are well situated. The sit bones of your hips are designed to support weight for long periods of time, where a plush seat disperses your weight to muscles and other areas.

The chamois is a crutch for an ill fitting saddle and bike set up. Chamois are "gaskets". They hold moisture, bunch up, grip soft skin, causing friction that heats and causes burns, etc. They get worse with slight aging. If the saddle is the right shape for your groin, there should be no "gasket" introduced to the groin. My personal preference is a leather saddle (I use the B17 Brooks) that "gives", breathes, wicks away moisture and stays cool. I use a chamois-less Lycra short that ventilates immediately. With over 50 years of riding several thousand miles per year, This is what works for me. I have a garage full of saddles, many that I've modified. Cheap, ludicrously expensive, you name it. My next to best favorite (BTW) is the Selle Italia SLR superflow 130mm. Big cut-out, very thin padding, flat front to back, and narrow. Again, I use no chamois. 100 mile rides are easy. Once I wear out the Selle as a "now and then saddle", I'll just swap the B-17 around on the bike of choice for the day. It won't wear out in my lifetime. My original was built in the mid 70's and the replacement was built in 2013.


Tips for a novice cyclist wanting to get fit with a turbo trainer before summer I have decided to have a dalliance into cycling since a lot of people I know are quite into it themselves.

I have bought myself a bike (Specialised Tri Cross). Only a cheap, used one for now as I can always buy a nice, expensive and more lightweight one further down the line if I find I need it.

I chose a cross/adventure/gravel bike as I do intend to go slightly off-road, along river/canal paths on my travels, rather than being stuck to the road with a specific road bike.

I have also bought a turbo trainer (Tracx Flow smart trainer), along with training tyre so that I can get cycling no matter the weather.

My plan is to make the most of the turbo trainer whilst the weather is less than nice outside, after work so that (hopefully) I can have some sort of fitness for when the summer and the warm(ish) weather comes.

My question for the bicycle.stackexchange community is, how would I best go about doing this?

A lot of cyclists find they need motivation to train on a static trainer. It can be unrelentingly tedious to sit spinning on you bike staring at the same wall when you are used to nice scenery going by. If you are used to running on a treadmill or a similar exercise this may not be such a problem for you.

As you have a smart trainer that will work with Zwift, I'd recommend getting a subscription and taking advantage of the structured workouts they offer, and the motivation of virtual cycling courses and competition. You only really need a laptop or tablet to create a workable set up.

If you are not going to do Zwift, there are structured training videos for 30-60 min workouts on you tube that you can use. The Global Cycling Network has some pretty good ones.

You'll want to figure out what your goal is for when you transition to outdoor riding and pick appropriate workouts. E.g. if you live in a hilly area you would want to train for hill climbing, or if you want to do long rides select workouts that build endurance.

As a novice, one option would be to not overdo it. Say twice a week for 30-40 minutes (or just 20 if your butt or arms hurt too much), don't worry about structure. The main benefit will be some basic "can stay on the bike for an hour without pain" adaptation, so when warmer weather comes you can immediately start with 40+ km rides.


Cracked rim around the spoke I purchased a pair of Carrera Vendetta wheels, 27.5" with 2.8" tyres.
I found a couple cracks where the spoke sits around the back rim.
Is it okay to ride or is it okay to weld them?

Cracks in the wheel rim do generally need attention. If the cracks are around the nipple and you're a gambling man you can keep an eye on the crack's propagation and maybe use it a little, if they're in the side/wall, it's possible failure will be a little more exciting.
If you purchased them recently you may wish to return or exchange them.
Welding is probably not an option (assuming they're aluminium).

I found a couple cracks where the spoke sits around the back rim.

There are a number of reasons why rims develop cracks:

The rim is so light weight that it's not even supposed to last. A quality 622mm rim will weigh over 500 grams.
The rim may not have double eyelets. Almost always, these cracks are found on rims that are double wall rims but lack double eyelets to distribute the high spoke tension evenly to both walls of the rim. Thus the outer wall that is over-stressed cracks. To avoid this problem in the future, choose a rim that has double eyelets. Note double eyelets have compatibility issues with tubeless tires. Considering that tubeless might not be such a good idea after all, the choice between rims that don't crack around the spoke holes and tubeless is easy: choose the types of rims that don't crack.
The rim may be anodized. Anodization is an optimal surface for cracks to appear and grow. To prevent this problem in the future, choose rims that have a high polish finish. The smooth surface of a polished rim is not a surface where cracks would easily appear. But oh, you can't buy polished rims anymore because everything has to be black nowadays. Fortunately, rim manufacturers have discovered that it's possible to make black rims by powder coating instead of anodizing. Powder coating doesn't have a tendency to crack. Choose a powder coated rim over an anodized rim.
The rim may have too few spoke holes. Historically, quality wheels where made with 36 spokes. However, after The Great Spoke Scam, wheels with fewer than 36 spokes started to be fashionable. Resist the fashionable tendency to choose wheels with fewer spokes and choose wheels with full complement of spokes (36). Note the Sheldon Brown's advice about front wheels needing fewer spokes than rear wheels is obsolete today due to the prevalence of disc (hub) brakes. The advice to choose fewer spokes on the front wheel may have been good advice when rim brakes were used, but not so good advice anymore with disc brakes. 36 front and 36 rear is optimal.
The spokes may be of an incorrect type. Ideally, spokes should be as thin as you can make them (so the elastic thin spokes distribute spoke tension over a larger number of spokes). However, spokes have a tendency to fail on the threads or J-bends so these sections should be made thicker. The ideal spoke used to be 1.8mm/1.6mm/1.8mm when the spoke holes in the hubs were made for 1.8mm spoke J-bends and threads. However, today spoke holes of most hubs are oversized to make spoke installation fast (which may result in less wheelbuilding minutes but definitely won't result in a good wheel), so spoke manufacturers have started to offer 2.34mm/1.8mm/2.0mm spokes which may be the optimal fit for today's hubs with ridiculously large spoke holes.

By following these advices (not too light rim, double eyelets, polished or powder coated rim, 36 spoke holes, 2.34mm/1.8mm/2.0mm spokes) you will get a strong wheel but the wheel needs to be properly built too: the builder must tension the spokes to an even and high tension, the builder must take spoke winding into account when tightening the spokes, and the builder must stress relieve the wheel. Wheelbuilding machines usually don't do these steps so machine-built wheels are not as strong as handbuilt wheels.
Fear not, there are cyclists weighing over 100kg riding on over 15kg bikes transporting 30kg cargo and properly built wheels don't fail for them in any manner.
So what can you reuse on your existing wheels?

If the hub has 36 spoke holes, you can reuse it; otherwise it should be discarded
If the spokes are triple butted (2.34mm/1.8mm/2.0mm), you can reuse them; otherwise it's better to start with fresh spokes
If you can find a rim with at most few millimeters of difference from the effective rim diameter of your current rim, you can use the same spoke length (so reusing spokes is a possibility if they're good enough quality); otherwise you need a different spoke length
Nipples could be reused but if you have the unfortunate experience of using aluminum nipples it's better to replace them with brass nipples. Also, recently nipple manufacturers have improved nipples with a spherical seat (for example sold as DT Swiss Pro Head nipples) as opposed to a conical seat, and nipples are cheap anyway so if your nipples don't have a spherical seat or they aren't made of brass, it's better to start with new good nipples.

Is it okay to ride or is it okay to weld them?

No, it's not okay to ride apart from making a short ride safely home and/or to the bike shop. The wheels will eventually fail catastrophically.

its a tight one at the moment, i haven't really got the money to be spending another £100 on just one wheel.

A new wheelbuild costs perhaps around that. To add the nipples, spokes and quality rim you are spending nearly double that. To add a new hub (if your existing hub doesn't have 36 spoke holes) you'll be spending way over double the stated £100 amount.
But of course there could be countries where labor is cheap. In such a country, if your existing hub has 36 spoke holes, you could theoretically be able to get a quality wheel for as little as £100. But do note there may be a reason for labor being cheap -- for example, a wheel built by a good wheelbuilder will last thousand times more than a wheel built by a bad wheelbuilder.


Why would spokes break at the flange early? I have a professionally-built Rohloff wheel, 32-spoke, symmetrical, laced to Velocity Dyads with Sapim Race spokes, disc brakes. It is about six years old, built in 2011; but I mostly just use it when I go touring, so only about 5,000-6,000 miles on it. Always seemed very true, never wrecked, no unusual events.

On a recent tour, a spoke broke while I was stopped, eating lunch. I replaced it and tried to match its tension to the other spokes by tone-when-plucked. Next day, another spoke broke while riding on smooth pavement. I'd only had one spare spoke, so I rode for another kilometer or so minus one spoke, but that really put the wheel out of true. I walked until I found a kindly stranger gave me another 2mm straight-gauge spoke of about the same length.

When I put that replacement in, I de-tensioned all the spokes by about half a turn (thinking "maybe these spokes are too tight"), very carefully tried to equilibrate tension on all of them by tone, and trued out the deflection caused by riding minus one spoke. I finished the tour, maybe another 550 miles, like that, no more spoke breaks.

I'm going to re-spoke the wheel -- I don't trust any of the spokes in it anymore. But I'm also trying to determine a cause here. I don't want to have this happen again. Other points:

Rohloff pointed out that there was a bad batch of Sapim Race spokes at one point. Sapim says that batch was not in 2011, when these wheels were built (various internet posts make it look like that was 2014).
Rohloff support was like "sounds like a spoke problem, can't help you." (fair enough)
Sapim was like "doesn't sound like a spoke problem, can't help you" (no I don't understand that logic either)
My wheel builder has a good reputation but for whatever reason has not been responding to calls or emails, so no information there.
The breaks are 6mm and 13mm from the neck bend. So around the hub flange. Pictures below; I lost one of the spoke heads.

Any ideas on cause? My initial theory was that it was built too tight, but most advice online (and Rohloff support, and Velocity support who I also emailed) says that'd be unusual. I guess I just can rebuild and hope for the best, but it would be nice to have some sense of causation so as to prevent this from happening again.

I've broken a spoke on a well-built wheel simply from hitting a bump in the road a little too hard. And on a generic wheel, I've seen that when one spoke breaks, the spokes at 90° intervals from it start breaking, even after I replace the first broken spoke. My guess is that this reflects a pattern of underlying stresses. So neither of your spoke breaks surprise me that much.

Since this is a Rohloff hub, you shouldn't have super-high tension on just the drive side due to dishing, so we can rule out that frequent cause of spoke breakage.

It might be fatigue. Jobst Brandt regarded fatigue failures as a consequence of failing to stress-relieve the spokes when the wheel was built.

Could be a lacing issue or even try a different pattern.


Scratches on fork stanchions On of my fork stanchions has scratches on the black coating. The scratch has sharp edges.

The Fork is a RockShox Pike RCT3.

I could try to fill the scratch with paint and polish or replace the crown with standpipes. The replacement CSU unit for the Pike costs 316€

It really depends how deep the scratch is.  If it's deep enough, then a new CSU (crown-steerer unit) is the only sure-fire fix.

However, here are some steps I've taken in the past, which have given me some success:

Sand the scratch down to remove the burrs.  You can use super-fine wet & dry paper for this; something like 2000 grit should do the job without damaging the rest of the surface.
Clean the scratch and the surrounding area thoroughly with isopropyl alcohol, removing any debris from the scratch itself.
Fill the scratch with some high-quality epoxy.  I've used J-B Weld in the past with some success.  Some people have reported success with super glue or nail varnish, too.
Wet a razor blade (or something similar) with water and use it to scrape off the excess.  You want it to be as smooth and flat as possible.

Your mileage may vary here; if the filling comes off after riding, you might be looking at a new CSU if you want a complete fix.  The fork will still work, of course, but a gap will allow dirt into the lower legs, which will effectively shorten the service interval on the fork.

I've successfully repaired a nick in a Fox RP2 rear shock like this, and it's still going strong today.  However, it didn't work so well on the stanchions of my TALAS 32, since the filling wouldn't stick for more than a couple of rides.

If you just want to hide the chip a little just touch it a couple of times with a black sharpie pen. If that's not good enough,  get a suitable vehicle touch-up colour & the lacquer, and do it properly.

Ah sorry.. I didn't realise the image was of the inner fork leg.

The only permanent option here apart from a new part is to remove the inner fork leg and take it to an engineering workshop.. A good shop should be able to grind the leg down in the damaged area. Then either fill it and machine it back to size, or spray weld it which is a different process to fill the damaged area, then again machine it back to original diameter. Filling by welding can be done with most materials in one way or another.


Independent drivetrains on tandem bicycle On a standard tandem frame, is it possible to build a tandem bicycle with independent drivetrains for the two riders? Is there a custom frame builder that would build a tandem like this?

I'm aware of the half-recumbent tandem that has independent drivetrains, but I'm specifically interested in the classic/normal tandem frame.

EDIT: By independent drivetrain, I mean that I would like each rider to be able to coast independently of the other. The cadence can remain constant between front and back when both are pedaling.

Here's a picture of a half recumbent tandem

from https://www.ucycle.com/merchant/2856/images/zoom/hase-pino-allround.jpg

Here is a link to a video of people riding a recumbent tandem.
https://binged.it/2TXkxJC
The video does a good job of explaining that the front crank has a freewheel mechanism that lets the riders pedal at different speeds. The front rider can also stop pedaling.

If this is what is meant as "independent drivetrains" then the functionality is in the crank rather than the frame itself.

The key to having a regular tandem like the recumbent tandem in the video is to find someone who makes a crank with a freewheeling chain ring. Like the old school Schwinn Suburban's from the late 70s with Shimano Positron FFS (Front Freewheel System).

Here's a link to a product for mountain bikes with a freewheeling chain ring
https://dirtmountainbike.com/news/hxr-easy-shift-crankset-allows-change-gear-without-pedalling.html

With this part - or something like it - any tandem frame builder should be able to get you going.

The Performer Family Tandem is made in Tiawan. It has 2 drive options.

27 speed option uses a timing chain to lock the recumbent stoker and the upright captain together with the same cadence.

the FWD 30 speed option has two fully independent drive trains with the recumbent stoker driving the front wheel and the upright captain driving the rear wheel.

https://rbr.info/index.php/product/family-bike-tandem/


Can I clean out a set of old handlebars with water? I've bought these bars second hand and would like to clean them out before I use them. Right now they're full of dust, dirt, spiders, etc.

Will it do any damage to run water through them? I'll, of course, let them drain and dry before putting them to use.

Its totally fine.  For bars with impacted dirt in the ends I have used a blunt screwdriver to dig as far in as possible, then put water in and leave it to soak though the dirt.  Adding dishwash liquid helps too.

You should be able to poke a wire or string all the way through the bars.

I'll use a hot air blower to dry the whole bars outside and inside through both ends.  Also I hang it up to save burning the fingers.

Once its cooled down again, I sand any imperfections, and then use an aerosol spray can of anti-rust/primer to blast down both ends of the bars in turn.  Its not going to coat all the inside, but should help longterm, specially right at the ends.

Then I prime the outside, wait, sand, top coat, wait, (sometimes I do a clearcoat)  and then reassemble carefully.  Fit new grips once the brakes and stuff are on.

If you have a forgiving spouse (or they are out of town), then you can run it through your dishwasher.

Be sure to run an empty load after it and also get rid of any incriminating spider parts that might be stuck in the output filter.

Pro-tip: Only dishwash parts that don't have any bearings in them. The problem isn't (just) washing the grease out of the bearings, it's that the grease will transfer to other parts of the dishwasher and can be hard to take off or otherwise explain to your spouse.


What are the consequences of riding a bicycle tire backwards? When putting a new tire on a bicycle, there is usually a note somewhere on the sidewall showing the direction the tire is supposed to rotate when you are on the bicycle.  However, the last time I changed my tire I already had the tire mounted on the rim and inflated before I remembered to check for this marking, and it turned out I had it backwards.  Rather than take the tire off and do the whole thing over again - or leave the tire to rotate "backwards", I opted simply to put the wheel on backwards, as it was the front tire and there did not seem to be anything dictating which side of the bike the quick release had to be on.

I have ridden about 20 miles so far without any issues, but I am wondering, what, if any, are the long term consequences of either this approach (riding with the tire backwards from the standpoint of the rim being backwards with respect to the quick release being on the opposite side from the back tire), or simply riding the tire in the opposite direction as labelled on the tire.  For the latter, I am wondering if it really makes any difference, because in my case I had to really search for the direction indicator as it was barely discernable.

I'm riding a road bike (touring geometry) and the tire itself is a long-life, hard casing type, as opposed to soft "performance tire" types which get flats more easily but are supposed to handle better.

If it's a road tire, i.e. a slick, it makes no difference. The tire direction marks are usually printed on road tires because mechanics are so used to looking for them, that the makers may as well put them on there so as not to confuse or waste the time of the installer.

http://sheldonbrown.com/tires.html#direction

If you ride it backwards long enough the tire can fuse to the rim. Thats what happened in my case at least. I had ridden hundreds of miles with the rolling direction backwards and when I went to take the tire off of the rim to replace the tube it was as if it was super glued to the inside edge of the rim. The only way I understand it is that because it was backwards it caused some sort of friction that made it stick to the the rim over time... so I wouldn't recommend riding with your tire backwards for long periods or that could potentially happen to you.


carbon frame chipped today while I was riding I lost control of my bike; it was nothing serious, I even fell "standing", but my bike fell on a rock and the carbon frame was chipped.

Should I worry about the damage?

I read posts about using nail polish to "cover" the damage, would you advice that?

Thank you a lot!

The damaged part is the top tube, close to the handlebars.

Here is a photo of the damage:

As far as I can see from your photo, the damage to your bike caused the paint to fleck but the underlying carbon fiber looks intact. Doing anything anything abrasive would risk damaging the fibers. If your bike is under warranty, I'd ask the manufacturer. If not, I'd carefully paint over the chips so as to seal it back up and prevent further damage (physical and UV) to the underlying carbon fiber.

If your bike is of recent make, the manufacturer or your local bike store (LBS) can get touch up paint in the right color. Again, you might want to inquire with the manufacturer what you need to do to maintain your frame warranty.

If you can't find the exact color through your LBS or the manufacturer, you can go to an auto parts shop and look at their array of touch up paints and get something near enough. This might be difficult as the chips are in an area where the color is fading to black.  A color that is too light will generally be less noticeable than one that is too dark.

While you're at the parts store, get some clear coat as well.  The little touchup paint bottles should cost about 3-8 Eurodollars each and come with their own little brushes.

Now, with metal frames and when you have an exact paint match, you want to sand down the metal so that you can remove any oxidation and lay down some primer. But you have a carbon frame, the damaged area is so small, and sanding may cause more fibers to abrade so I wouldn't risk sanding it.

Instead, I'd clean the area with some isopropyl alcohol and then apply the touch up paint very carefully. The area is so small that you likely won't need primer either but if you got some, it wouldn't hurt. Thin layers applied multiple times with time in between to dry is better than a blob of paint.

After the final layer had dried, apply the clear coat.

Ps. Don't use clear nail polish lacquer as it yellows under UV and age and is quite brittle. It's only designed to last a few weeks at most and then its removed and reapplied.

Don't let it get wet. That is a big enough patch I would sand lightly with 600 and cover the entire patch with 2-3 coats of nail polish or touch up paint.


Rear axle sizing for wheel set, compatible with both 142mm thru axle and 135mm quick release? Attempting to buy a new wheelset and I am getting a bit confused on whether the wheelset - or I guess more specifically the hub will fit my bike. I have a Salsa Journeyman Apex 1 and it has quick release dropouts.  The specs on Salsa's website say the rear spacing is 135mm. So I would need to select a wheel set suitable for QR x 135mm.
I am looking at this rear wheel which lists compatibility with 12mm thru x 142mm as well as QR x 135mm. However a lot of sites don't list the QR compatibility for this wheelset, like this one.
I will be getting the wheel with a SRAM XDR so final question would be, does a SRAM XDR 142mm thru fit a bike with 135mm QR? Do I need to get different end caps to fit a QR system if so or will it come with thru axle end caps and QR end caps?

135 QR and 142x12 thru axle are two wholly different standards with no intrinsic cross compatibility.
They both locate the cassette in the same place relative to the frame centerline, or in other words they give the same chainline. 142x12 is essentially the iteration of a thru axle rear end that didn't change anything else about the parts that would play nice on the rest of the bike, coming out of the long period where 135 was the only game in town for a disc bike.
All that said, it's extremely common for aftermarket 142x12 wheelsets and hubs to have 135 QR adapter endcaps either included or available. These are all proprietary to the hubs they're made to go in. It's pretty common for them to be included and I believe that is the case for the DT wheel in question.
Whether the freehub body is XDR or XD or HG or Microspline or whatever is immaterial to the frame the hub is going in. All that matters is either endcap availability or native compatibility with the standard the frame is made to.

I'm extremely wary of what online retailers say about their products. I also would not assume that all 12mm TA / 142mm wide hubs are convertible to 135mm with some end caps. If the hubs are wider than 135mm end caps cannot make them narrower. (A friend of mine recently made this mistake with some Roval wheels.)
The first thing to do us look at the specs on the DT Swiss page. DT Swiss does not explicitly state 135mm/QR compatibility. What is does say is 'Built in Dimension' is
142mm which heavily implies they wont fit in a 135mm frame, but then a '5mm endcap kit' is included which rather implies they will.
Next step - find the Spline Wheel Manual via the support page. This explicitly gives instructions for converting both front and rear wheels with end caps so I'd say you were good.
If you really, really want to be sure, contact DT Swiss directly.


Is it considered rude to draft other random cyclists? On my commute to work, if there a cyclist in front of me, is it rude to catch up and draft?  To effectively draft I would usually need to be within a foot of their back wheel.

There are two situations:

Trainers
There is one part of the commute that is often used by individuals and groups of riders who seem to be training rather than commuting. Generally I would draft these guys if I can sprint to catch them.  As they are going quicker than I can sustain, I never take a turn at the front.

Commuters
I think any fellow commuter is probably ok to draft and if they slow down enough I'll take a turn at the front.

There was a post on this subject on The Guardian Bike Blog.

I think there are a couple of issues with drafting random cyclists:

it could be unsafe, particularly if they don't realise you're doing it.
some people will object to being drafted - it can be considered an invasion of your personal space.

I think your best bet is to ask before drafting, then there's no problem.

Really this question is 'chatty' and therefore doomed to be closed, however...

No it is not rude!

Drafting should be taught at school as part of a Cycling Proficiency Test so that some conventions are established. This would encourage people to cycle together, taking turns up front and doing so more efficiently. Elbow twitches to get the guy behind to take a turn need to be an accepted convention and ladies not wanting a 'crafty drafter' behind them should be able to use this if they are not happy with whomever is following them.

Every time you draft someone that thinks it is rude you are helping to break down their 'hostile' attitude. The truth is that one should be flattered to be drafted, particularly if you are old, with a rubbish bike or carrying loads of stuff. Drafting goes on, whether you like it or not, and the reality has to be lived with. If you really do not want to be drafted you could always put a big sticker on the back of your seat saying 'DO NOT DRAFT!' - 'L' plates for the bike as it were.

Clearly there is the problem of stopping suddenly for some drafter to go into the back of you. However, there are ways to deal with this potential threat. First of all, think of who is the most scared of a crash - you or the guy behind? The guy behind is not going to be right on your wheel if they are not experienced enough to draft close up. If they know what they are doing and know every pothole in the road then they might be up tight.

By convention, in a crash, it is the guy that goes into you that is at fault. You could have a car door or other instant stop requirement, however, if some cyclist goes into the back of you during such an incident, you do have to ask yourself a few questions about your own riding and not just blame the other guy. Even though the roads are full of hazards it is for you to anticipate and ride accordingly.

As for 'providing a wheel' there should also be some convention to signify that this is being offered. Cut too close in front of someone and you can have some wheel entanglement, go past too fast and they ain't going to make it. When riding with a weaker rider and wanting to put in a good collective time successful drafting makes all the difference and it really should be taught at an early age.

Incidentally, my 20" wheel 'shopping bike' is excellent for drafting. It is about a foot shorter at either end and that extra bit of proximity really helps whether up front or behind.


What bmx logo is this please? I was told it was an American rally but have been unable to find anything of that make. It was originally in chrome and has for some reason V brake lugs at the back.

Bmx panther originally made in colarado i recall.


Ideal pants for bicycle commuting the rain I commute about 10 miles a day in Portland, OR.  Needless to say rain is a big part of many of my rides.  My current rain pants leave me almost as sweaty as if I had just ridden without the rain gear.  So I'm looking for pants with a hard shell/ gore-tex/ dwr front and soft shell sides and back.  I figure that this combination has to exist out there and that it would help with my moisture transfer issues.  Who makes my Holy grail of rain gear?

Which pants do you have right now? And did you enjoy that downpour yesterday? There wasn't a dry cyclist in the city, breathable pants or not. Some days we're just going to get wet.

Showers pass is made right here in portland, and I use them on all the nasty days, for me they work great http://www.rei.com/product/821425/showers-pass-roadie-event-bike-rain-pants-mens

Arc'teryx, even though I can't pronounce their name, make the top of the line holy grail rain gear. I was just looking at these for myself yesterday: http://www.rei.com/product/836409/arcteryx-micon-insulated-pants-mens

Showers Pass easily have the best cycling rain pants hands down. They do a whole write up on how to pick the best cycling jacket, cycling pants, etc and they are based out of Portland too!


Mongoose Malus Chainring upgrade I have a mongoose malus. It has a 36t chainring in the front and a 7 speed in the back. If I wanted to have higher gears can I replace the front chainring?

This answer is based on wanting faster gearing, higher ratios.

To go faster you need to have smaller/lower tooth count cogs on the rear cassette, or a larger chainring.   Or both.

There is a physical limit of about 13 teeth for a freewheel and 11 teeth for a cassette.   There are BMX bikes and folding bikes that can go as low as 9 and rarely 8 teeth, but they require special wheel hubs.  SO if you're already on an 11 tooth small cof on your cassette, the only option is to upsize the front chainring.

Your main problem is clearance for a larger chainring.  Firstly it has to clear the right-side chainstay.  If that doesn't fit then you're out of luck.  Start with a cardboard template to see how much lager a chainring you could fit.

Then check clearance in all other directions - your breakover clearance (how close you are to the ground) will decrease.   Your front wheel will probably clear things, because it has to clear the pedal when in the forward position.  Upwards should be fine, but depending on your frame check all possible.

If your existing chainring is rivetted onto the crank spider then you're stuck, and will have to buy a new crankset.

Otherwise you'll need to find the BCD of your existing chainring.  Take it off  and print this PDF at 100%  then compare.  You will get an answer like 64, 88, 94, 96, 102, 104, 120.  If it doesn't match, check your printout was 100% scale.

Then buy the biggest chainring that will fit, that has the same BCD as your existing crank-spider.

Finally you'll need to add more links to your chain, so just buy one or two new ones.

The Malus is a freewheel NOT a cassette. shimono does make a 34mm with I believe 14 teeth which Ive head good things about just in research but as far as additional parts Im not sure they are required as they work with the original twist gear.


Tubular tyres on carbon tri bike I have a full ironman scheduled in 2018 and will therefore be doing a lot of mileage next year. My question is, if I get a flat during the race, is it basically race over as it is unlikely that I or mechanic will be able to fix
at roadside or is there a quick fix solution to get me to the end of the 180k race?  PS - I am a female and not good at changing tyres quickly at the best of times

It is a matter of personal preference.  Triathlons generally have to be self supported (with some exceptions) so getting a full wheel swap like in Pro Bike races is not an option.  I run clinchers mainly for this reason as they are easier (for me) to swap out on the side of the road.  However, depending on your rim/tire this can still be pretty tough sometimes.

So if you are running tubs you would have 2 options:

Carry a spare tub tire & CO2.  You would need to be able to peel off the old tire, re-seat the new one, and re-inflate. This can be pretty hard.  Also, usually when you glue on new tubs at home you use fresh glue and let then set awhile to make sure they are well  adhered.  However, in this case on the side of the road you will be re-using the old glue or you could try tube tape (never used it personally).  This is a bit dangerous as now your tire is not as secure onto the rim and you risk "rolling" it off in hard cornering ...
Carry a sealant like Vittoria Pit-Stop.  This might seal & re-inflate your tire but if it doesn't then you are out of luck.

Consider clincher and go with puncture resistant.  In the 28 or 32 width to resist pinch flat. Not adding much weight. A benefit is you don't need to change out from training to race tires.

Most races you are not going to flat. You may go the whole season with no flat.

Practice changing flats.  You may be out of contention for the win but you can still finish the race.

If you have not bought wheels and want to go tubular then that is certainly an option.

Don't cut the last 6 inches of the corner as that is where most debris is.


Why does my Rear bike tire slow down when Pedaling? I just replaced a flat on my rear road-bike tire. I had also tried to replace the rear axle, By removing the axle completely, to a quick release lock but realized the axle that had been installed with the bike tire wasn't hollow so put the old axle back on the bike, seemingly correctly. This morning i went for a ride and when I put any pressure while pedaling it felt as if the rear breaks were engaged. I checked to see what would happen if i pedal with the rear tire in the air and the tire seemed fine but came to a stop more quicker than usual but nothing too alarming.

It seems the problem only occurs when im siting on the bike and there is weight. I also noticed when i pedal the rear derailleur seems to tug forward and hug the rear cog set. im not sure if that's the issue...

Any ideas? I was wanting to save some money by not going to the LBS and learning and doing it myself. But I may have to go anyways.

Here are some images of the bike

By far the most likely reason is that you've over tightened the bearings.

Did you feel as if you needed 3 hands to get it back together? If not, you did it wrong. :)

As usual Sheldon has a pretty good writeup on this, but the basics are easy enough.

Put one side back together, tighten it up as best you can. Set the cone on the other side to the correct tension. Tighten locknut on second side without turning either cone.

The tricky part is the last bit. You need to hold the cones on both sides at the same time whilst tightening the locknut and you really need 3 hands.

You will most likely have to try a few times to get the tension just right. When it's done it should turn freely but not have any wiggle.

It is the common problem when bearing does not wor properly so you need to change the bearings.


Is a chin strap with a cup safer than an under-chin strap? Many helmets have chin straps to hold them on.
One design uses a split chin-strap, where the strap splits into two forming a cup shape, one going just below the lower lip and one under the chin.

In my opinion, this is a more comfortable design as the chin strap is against the chin bone instead of pressing against the fleshy underside of the lower jaw.

I found a single link http://www.usyouthsports.org/images/CPSC_Hangman_s_4_point_chin_strap.pdf which claims that this design is safer for bike helmets as it may reduce some cases of strangulation in case a "yanking" force is applied to the helmet.

Were there any other studies done on chin strap design like this for bike helmets?
Is this design safer?
Are there any bike helmets actually available with this chin strap ?

Helmet strap will strangle kids, there are cases of children in play grounds not being able to get out.
I would add the magnetic buckle as the solution to these problems. e.g.
https://www.fidlock.com/en/helmet-buckles


Is it possible to get a light that is too bright? This question is related to this recent question: Best ways to avoid getting hit by cars?

I have a 750 lumens front head light - it's bright! Some of my riding buddies say it is too bright for the streets as it blinds drivers. I disagree that it is truly blinding drivers and think that means it is just doing a better job of making me visible. Is it possible for a light to be too bright?

Another consideration for this is bike paths at night. Obviously a light doesn't need to be as bright on a bike path as a busy city street, but I do feel bad for the oncoming pedestrians that seem to be wincing when I approach. What is the proper etiquette for approaching in these situations. Turning off my light doesn't seem like a good idea. Also, I'm not really interested in jimmy rigging a lens-guard on my light, or purchasing a new one (Bike lights with beam cut-off to avoid dazzling drivers?).

As a side note, on a couple occasions, drivers at intersections have complimented my lights noting how easy it was to see me! I assume they are referring to my tail light, though.

Blinding road users will be the result of the following factors:

Total light output
Mirror design (how is the light shaped)
How you aimed your light

Most trail lights (and high output battery powered lights) use a mirror that casts the light in a symmetrical shape.  This means light is cast up, down, left and right.  Light cast above the horizon is what binds other road users.  Light above the horizon is however great for trail riding as it lets you see overhanging branches and other impediments.

Car running lights (i.e. not high beams) are designed with a horizontal cut-off, where light does not shine above the horizon (actually a low percentage does, this called spill light). If the car light is aimed correctly, the the horizontal cut-off falls below oncoming road users line of vision.  This is why you are typically not horribly blinded by oncoming cars, if they are a) using their running lights and b) have their lights aimed correctly.  High beams do not have a horizontal cut-off, which is the primary reason you get blinded so badly.

Some bike lights (those that are approved for German roads) will have a mirror that has this sharp horizontal cut-off.  They usually will usually be indicated by the some statement on StVZO compliance. Most dynamo lights (e.g., B & M, Schmidt, etc) will have this mirror design. There are also a few battery powered lights (e.g., some B & M models), but they are few and far between.

If you have a light with a symmetrical beam, you can lessen the blinding effect by pointing the light down (as suggested in @Batman's answer), however due to the symmetrical nature of the beam you will still blind road users more than if you had a light with a horizontal cutoff and was aimed correctly as there will still be more spill light above the horizon. This effect is also confounded by how narrowly or wide the symmetrical beam is focused.  Wide flood lights will almost always blind, despite how much you aim them down, spot lights will blind less when pointed down.

Finally, total output does have some impact too, but it is also confounded with mirror design (e.g., high output with a horizontal cut-off may blind less than a low output symmetrical beam).  What really determines whether or not you blind other users is the total amount of light shining above the horizon at their eyes.

In your case your 750 lumen lights are likely trail lights with a wide symmetrical beam.  If you run them at full output you will likely blind others unless you severely aim it downwards.

How to put this politely.... Disagree with you buddies all you like, but stop being a Selfish Cyclist who cares for no one but himself. Consider that your actions in running a light that bright on the road are the ones that make otherwise normal drivers cyclist hating psychopaths.

The law will not be on your side if your light is bright enough to be blinding or distracting to drivers. Unless it has proper optics behind it, 750 lumen on the road is too bright, your friends are right.

The end game of too many people running these lights at full brightness are laws banning anything other than standards approved lights, These approved lights won't cost $10 or $20 or $50 dollars, they will cost $500 or $1000.

If you want to be safe, add more lights and reflectors to your Helmet, arms, body, wheels....and High vis (white) clothing.  Light from one point cannot be used to judge distance. The more points, the further apart, the more accurate and quickly the driver can determine the distance between you and him. Use flashing to attract attention but steady lights are needed to judge distance accurately and quickly.

I run 2x 1000 lumen lights off road (usually on mid setting), as soon as I hit the road, I turn them down to low (about 250 lumen). Its clear cars have no problem seeing me at those levels.


Shimano 105 Rear Derailleur Housing Frayed While adjusting my rear shifting cables I noticed that the small piece of housing, which emerges from where the barrel adjuster is threaded in, was broken. Is it necessary to replace this or is it fine to leave it as? If I should replace it, what is the part name I should be looking for.

It's there to reduce friction when the derailleur is in its extreme positions and also to prevent contamination of the housing. It's not totally necessary, but if it's broken in a way where it can't do that anymore, replacing it will improve performance.
It's unfortunate that the first generation Shimano road 11 rear derailleurs were built to need them to perform well, but they do.
Shimano sells them. I believe their part number Y5XX38000 is a generic replacement for all the derailleurs that have it.
You can also remove it completely when the housing is out and replace it with any sufficiently long nosed shift ferrule to accomplish the same thing. It doesn't have to poke out as much as the original, only enough to route the cable around the bend that gets created in the extreme positions.

Most likely you are fine to leave it as-is.
It is actually not housing but rather the housing end cap with tongue.
The theory of the tongue is that it will prevent dirt ingress to cable housing, thus keeping your shifting reliable over time with no need to change the cables and housings regularly.
Long time ago, road bikes used end caps with O ring on the chainstay cable loop and unsealed end caps elsewhere. It worked just fine. But back then cog pitch was around 5 millimeters with 8 speeds and cable pull ratio was 1.7 so cable pull per shift was around 2.9 millimeters. Plus, back then exposed cable runs were the norm.
Then someone thought that hey, let's make bicycles need more frequent service and let's make the service more expensive as well. The way to make bicycles need more frequent service was made by introducing ridiculous 11-speed cassettes that have cogs so thin they wear away in no time, and cogs so densely packed that they had 3.7mm spacing. The way to make service more expensive was by introducing internal cable routing, a totally ridiculous feature only making it practically impossible to easily replace the cables and housings.
With the 1.7 cable pull ratio, 3.7mm spacing would mean 2.2mm per shift, a so small value the shifting would be unreliable. Not only that, but if the internal cable routing has housing for the entire run of the cable, cable friction skyrockets. Not feasible. Fortunately, Shimano has made the ridiculous 11 speed cassettes and internal cable routing more feasible by changing the cable pull ratio to 1.4. Then the cable pull per shift is 2.6mm, far closer to the 2.9mm ideal of 8-speed systems.
The newer systems that have 11-speed cassettes very closely spaced and internal cable routing with housing for the whole run of the cable are so sensitive to friction that Shimano has introduced new ways to combat dirt ingress to the inside of the housing. The housing end cap with tongue is one of these ways. Also you'll find that today's systems use "Optislick" inner wires having a faint blue color that are far more expensive but have minimally lower friction.
Next time when you notice your shifting has degraded and replace the cables and housings, put a new end cap with tongue there. Oops, you can't do that easily anymore because of the internal cable routings!


Switching from a mountain bike to a road bike I will be moving soon because of my work and the new area is not very "mountain bike friendly" as it is very flat and there aren't much hills or mountains around.

So I think of buying a road bike to keep practicing and maybe commuting to work. But I know nothing about road bikes and I have never ridden one before.

What are the main things I should be aware of when buying one that are fundamentaly different from a moutain bike ?

The bike I currently have is a Lapierre Zesty 414 with tubeless tyres. I'm also quite tall (1m95 or 6'4") so I'm wondering if it may cause any problems.

You will find the differences are significant.

When you say a road bike, we understand a bike with drop handlebars. Drop bars give you a very different riding position compared to an MTB. Some people need time to adjust to the new position, and can have problems with weak or tired neck muscles.

An alternative would be a hybrid style of bike, with flat handlebars. This would be much closer to the riding position you are used to.

The thinner, smaller, slick tires will provide two more differences.

One is much less cushioning, so you'll feel bumps more. The other is they'll be much faster. So you'll ride faster and feel any bumps in the road more.

As a consequence, some people get sore hands or wrists.

The other main difference is how light the bike is. On any medium quality bike (or better) you'll feel like you suddenly got on an F1 bike :-)

When switching to road cycling, make sure you have well padded gloves to absorb road vibration. And the bigger the change in riding position from your MTB, the more gradually you should make the change. Keep the MTB and ride the new bike for a few days, then switch back. If you start feeling sore then give the new bike a break for a day or two.

It may sound like I'm talking road bikes down, but as a road-only cyclist I am keen for you to get the best out of the change. You'll quickly discover that each kind of cycling has it's own different pleasures.

What are the main things I should be aware of when buying one that are fundamentaly different from a moutain bike ?

The main thing to be aware is that road bikers are obsessed with not only light weight like mountain bikers are, but also about aerodynamics.
Thus, you will find stupid "aerodynamic" wheels with less than 36 spokes in many road bikes. Needless to say, you should stay away from such stupid wheels. Most reasonable-spoked (36-spoke per wheel) bikes are not marketed as "road bikes" but rather as "gravel bikes" or similar.
You will also find that the stock tires are very likely extremely unreasonable 23mm ones, despite the fact that 23mm tires give worse rolling resistance than say 28mm or 32mm tires. This is because of the fact that many racing cyclists ride at such high speeds that the most important consideration is not rolling resistance but rather aerodynamics. Many road bikes cannot be fitted with >23mm tires. If you're lucky, 25mm might fit both front and rear. If you're very lucky, 28mm might fit both front and rear but then you will not have any reasonable tire clearance for mud etc. For non-racing speeds, 28mm and 32mm are far better than 23mm and 25mm.
You will also find that the handlebars cannot be raised to a reasonable height with the stock stem, unless you purchase a needlessly large bike, and if you purchase a needlessly large bike, the handlebars can perhaps be moved to a reasonable height but are too far away from the saddle and bottom bracket.
The obsession with light weight has gone so far that many road bike components are not durable despite the fact that with high-pressure narrow tires and no suspension, the components receive far higher loads than mountain bike components do. Thus, plenty of them fail early and often. This is exacerbated by over-using foolish materials like carbon fiber.
The chainstays are often very short, so if you're tall and pedal uphills sitting on the saddle, the front wheel rises from the ground. Such short chainstays are marketed as "light weight" and "quick handling". Reasonable chainstay lengths cannot be found usually on bikes called "road bikes".
You will also find that road bikes have wobbly brake levers, because of many buyers with $$$ feeling a need to be able to shift without moving hands. Thus, reasonable shift levers like bar-end shifters have gone nearly extinct. It will take some amount of time to get used to such wobbly brake levers, if coming from a mountain bike background where such wobbly brake levers are not used.
You will find that tire pressures are far higher. In fact with 23mm and 25mm tires you need so much pressure that any mini pump with reasonable design takes hundreds of strokes to fill the tire. A mini pump with larger stroke volume would require unacceptably large hand force. My solution to this is Quickex Quicker Pro pump that pumps on both in and outstrokes, but you can't find such pumps for sale anymore because the CO2 filling systems killed their market share.
The chainwheels are larger, but then again on road that's a necessity. On road bikes, the small chainwheel is typically the same size as the large chainwheel on MTBs -- too small for anything except uphills.
Many "road" clipless pedal attachment systems do not allow walking on the shoes, so stopping at a grocery store to buy something to drink is out of the question -- but then again, if you afford $4000 carbon fiber road bike you obviously cannot afford $2 drink at a grocery store and have to carry a water bottle with you (fortunately, nobody weighs water bottles so its added weight does not matter). Thus, you'll want to stay with MTB-style SPD systems even on a road bike.
Don't buy a road bike. Buy a reasonable bike. Some time ago, such reasonable bikes were most easily found by the name "touring bike" (although such bikes often had too low bottom bracket), and nearly reasonable bikes could be found by the name "cyclocross bike" (although such bikes often had too low handlebars). Today, the hot word for reasonable bikes seems to be "gravel bike".