From: iglesias@draco.acs.uci.edu (Mike Iglesias)
Subject: Rec.Bicycles Frequently Asked Questions Posting  Part 3/4
Expires: 15 Oct 1992 00:00:00 GMT
Newsgroups: rec.bicycles.misc,news.answers
Organization: University of California, Irvine
Supersedes: <rec-bicycles-faq-3_920808@draco.acs.uci.edu>
Date: 15 Sep 92 03:49:16 GMT
Followup-To: rec.bicycles.misc

Archive-name: bicycles-faq/part3

[Note:  The complete FAQ is available via anonymous ftp from
draco.acs.uci.edu (128.200.34.12), in pub/rec.bicycles.]

---------------------------------------------------------------------------

Studded Tires  (Nancy Piltch  piltch@ariel.lerc.nasa.gov)

[A summary on studded tires compiled by Nancy.  A complete copy of
the responses she received, including some that give directions for
making your own studded tires, is in the archive.]

Studded tires do help, especially on packed snow and ice. On fresh snow
and on water mixed with snow (i.e. slush) they're not significantly different 
from unstudded knobbies. 

On dry pavement they are noisy and heavy, but can be used; watch out for
cornering, which is degraded compared to unstudded tires.

Several people recommend a Mr. Tuffy or equivalent with them; one 
respondent says he gets more flats with a liner than without.

In the U.S. the IRC Blizzard tires are commercially available. They
can also be made.

---------------------------------------------------------------------------

Milk Jug Mud Flaps  (Chuck Tryon  bilbo@bisco.kodak.com)

  Actually, I have used plastic like this (or in my case, some
  red plastic from a cheap note book cover -- it's heavier) to extend the
  bottom (rear) end of the front fender.  The Zephals are good, but they
  don't stop the splash from where the tire hits the road from getting on my
  feet.  What I did was cut a small triangle about 3in (~7cm) wide by 6in
  (~15cm) long, cut a hole in the top of it and the bottom end of the fender,
  and use a pop-rivet (with washers to prevent tear out) to attach it.  On a
  road bike, it should be end up being within a few inches of the road.  ATB's
  will need more clearance, so this won't work well off road.

        |   |
        |   |
       /| o |\   <----- rivet with washer on inside
      | \___/ |
      /       \   <---- flap fits inside of the fender, and follows the
     |         |        curve, which gives it some stiffness.
     |         |
     |         |
     \_________/
         | | 
         | |     <----- bottom of tire
         \_/
        
===========================================================================

Touring

Touring supplies  (Scott "gaspo" Gasparian  gaspar@inf.ethz.ch)

	Recently, I asked the group: what do you bring with you on medium
trips? (medium being more than one nite, and less than a week).  I
received some excellent replies, a few great stories, and lots of things
that I never would have thought of. (at least not until I needed that
spare spoke that is).

Ok, for all of you who don't know what to bring with you on that
next medium trip...


FOOD: 	
	Here, just whatever you normally consume.  If you plan on
staying in a hotel/B&B, then obviously 1 day's worth is enough.
Standard things like power-bars and drink mixes should do the trick.
Since I'm not going to BFE, I have no idea what to pack for a real
"camp-out" type tour.  This subject is enough for a discussion in
itself, but I just eat what I want.

CLOTHING: 
	Almost everybody suggested something different, rangin from hi-
tech bodysuits to cutoffs and T-shirts.  However, everybody agreed on the
indispensibleness (tm) of rain gear.  Specifically, light waterproof
pants and jacket are not only good for staying dry, but have a very high
warmth/weight ratio.
	A spare change of skivies, and a pair of dry socks were also
highly recomended.  A pair of jeans or a "smushable outfit" can come in
handy, but I usually smell so bad after a day of riding that anybody who is
talking to me doesn't care what I wear.  If it might be non-warm, a
watch-cap or other non-helmet type hat can help.

FIRST-AID:
	Outside of the standard band-aids/antiseptic-goop bit, sunscreen
and bug-away topped the lists.  Asprin or Ibuprofen and rolaids were
mentioned, but I guess thats a personal thing, just like...

TOILETRIES:
	I stick with: soap, toothbrush/paste, deodorant.  That covers
all I need, but everybody has different needs, and I'm not even gonna
touch the "personal hygeine" stuff.  A razor is handy too, it can help
keep that road-rash dressing from ripping all your remaining hair out.

MISC:	
	I'll put the tent/pit stuff into this category.  Robyn Stewart
gave an excellent testamony to the uses of rope and tarps.  A piece of 
rope stretched between two trees can keep the food above the 
critter-level, and can also provide a rudimentary tent with the aid of
an old shower-curtain.  Again, there is a whole area of discussion here
on the pits and mattresses, but if it keeps you warm and dry, it works.


TOOLS: 	
	Basically, this could be split into two different classes, with
things like tire-kit being in the "fix it yourself" category, and other
stuff like a chain remover tool is in the  "how far will I be from 
civilization" range.  This was what I really wanted to know about when I
posted my request, so a little more info than the first groups.

Most of this depends upon how much work _YOU_ do to your velo.  If 
replacing spokes is trivial to you, then you already know what tools to 
bring.  Also, wrenches and screwdrivers are very velo dependent: handy 
sizes for a MTB might be useless for a nice racer, and vice-versa. Tools
that tune more than repair are also an individual call.  I always carry
a hex-wrench that fits my brake-shoe adjustment bolt, but never the larger 
one that actually removes the entire caliper.

	pump
	pressure gauge
	flat kit
	wrenches (sizes and type for your velo)
	hex(allen)-wrenches (sizes and type for your velo)
	chain tool
	chain links
	tire levers (plastic)
	spoke wrench
	safety wire
	duct tape
	zip ties

SPARES:	
	Again, these fall into "distance from civilization" categories.
For example, that nut that connects your front mudguard to the forks
is essential, but could be fixed with the safety wire until you find a
velo-shop/store that might have a replacement.  Then again, one little
nut is easy on space/weight, and it may be hard to get a replacement if
your velos measurements are non-standard.  If you have a hard-time
finding a replacement for that random part at your local store, bring
one with you.

	inner tubes
	tire-boots
	brake shoes
	light bulbs
	spokes (labeled if different, tied to the frame)
	nuts and bolts for rack/fenders/etc.
	tire (if you're _really_ out there)
	toe-clip strap
	shoe-laces
	cable (especially if yours are longer than normal).
	cable housing (for the shimano special shifter ones)

NIFTY IDEAS:
	Here are some of the better inside tips that I found both 
humorous and usefull....

mjohnsto@shearson.com (Mike Johnston)
	A sock (to keep tools inside and for keeping grease off my hands
	during rear wheel flats)

s_kbca@dante.lbl.gov (Steve Kromer)
	The most important article to take along on a long ride 
	seems to be faith.

chris@wg.estec.esa.nl (chris rouch)
	15cm of old tyre

Robyn Stewart <slais02@unixg.ubc.ca>
	Enough money to get Greyhound home if something goes terribly wrong.

sarahm@Cadence.COM
	bungie cords - you never know when you might want to get that 
	set of six beer mugs as a souvenir and transport it on the 
	back of your bike.

cathyf@is.rice.edu (Catherine Anne Foulston)
	ZAP Sport Towel.  I think it is really useful because you can 
	get it wet and it still dries you.

===========================================================================

Cycling Myths

Following are various myths about cycling and why they are/aren't true.


Myth: Wearing a helmet makes your head hotter than if you didn't wear one.

Actual measurements under hard riding conditions with ANSI standard
helmets show no consistent temperature difference from helmetless
riders.  Part of the reason is that helmets provide insulated
protection from the sun as well as some airflow around the head. 
(Les Earnest  Les@cs.Stanford.edu)


Myth: You need to let the air out of your tires before shipping your bike
      on an airplane - if you don't, the tires will explode.

Assume your tire at sea level, pumped to 100 psi.  Air pressure at sea
level is (about) 15psi. Therefore, the highest pressure which can be
reached in the tire is 100+15=115psi.  Ergo: There is no need to
deflate bicycle tires prior to flight to avoid explosions. 
(Giles Morris  gilesm@bird.uucp)
Addendum:  The cargo hold is pressurized to the same pressure as the
passenger compartment.
(Tom ?  tom@math.ufl.edu)


Myth: You can break a bike lock with liquid nitrogen or other gases

Freon cannot cool the lock sufficiently to do any good.  Steel
conducts heat into the cooling zone faster than it can be removed by a
freeze bomb at the temperatures of interest.  Liquid nitrogen or other
gasses are so cumbersome to handle that a lock on a bike cannot be
immersed as it must be to be effective.  The most common and
inconspicuous way to break these locks is by using a 4 inch long 1
inch diameter commercial hydraulic jack attached to a hose and pump
unit. 
(Jobst Brandt  jobst_brandt%01@hp1900.desk.hp.com)

[More myths welcome!]

===========================================================================

Buying a Bike

One thing to decide before buying a bike is what type to buy.  Here's a
brief list:

  Road bike    Once known as a "ten-speed", most are now 12 or 14 (or even
               16) speed.  There are several sub-types: racing, sport,
               and touring, the difference mostly in frame geometry.

  ATB          All-terrain bike, also known as mountain bike.  Great for
               riding in the dirt, these bikes usually have fat, knobby
               tires for traction in dirt and gravel.

  Hybrid       A bike that borrows from road bikes and ATBs.  For example,
               they have the light frame and 700c wheels of road bikes and
               fat knobby tires, triple cranks, wide-range derailleurs,
               flat handlebars and cantilever brakes from mountain bikes.


Bike buying hints

When you're ready to buy a bike, you should first decide what you want
to use the bike for.  Do you want to race?  Do you want to pedal along
leisurely?  Do you want to ride in the dirt?

Next, you should decide on a price range.  Plan to spend at least 
$350 for a decent quality bike.  

Now find a good bike shop.  Ask friends who bike.  Ask us here on the
net.  Chances are, someone here lives in your area and can recommend
a shop.

Now that you are ready to look for a bike, visit the shop(s) you have
selected.  Test ride several bikes in your price range.  How does it
feel?  Does it fit you?  How does it shift?  Does it have the features
you are looking for?  How do the shop personnel treat you?  Remember
that the shop gets the bike disassembled and has to spend a couple of
hours putting it together and adjusting things, so look for sloppy
work (If you see some, you may want to try another shop).  You might
want to try a bike above your price range to see what the differences
are (ask the salesperson). 

Ask lots of questions - pick the salesperson's brain.  If you don't
ask questions, they may recommend a bike that's not quite right
for you.  Ask about places to ride, clubs, how to take care of your
bike, warranties, etc.  Good shops will have knowledgable people
who can answer your questions.  Some shops have free or low-cost
classes on bike maintenance; go and learn about how to fix a flat,
adjust the brakes and derailleurs, overhaul your bike, etc.
Ask your questions here - there are lots of people here just waiting
for an excuse to post!

Make sure that the bike fits you.  If you don't, you may find that
you'll be sore in places you never knew could be so sore.  For road
bikes, you should be able to straddle the top tube with your feet flat
on the ground and still have about 1 inch of clearance.  For mountain
bikes, give yourself at least 2-3 inches of clearance.  You may need
a longer or shorter stem or cranks depending on your build - most
bikes are setup for "average" bodies.  The bike shop can help you
with adjustments to the handlebars and seat.

Now that you've decided on a bike, you need some accessories.  You
should consider buying

   a helmet
   a frame pump
   a tube repair kit
   tire levers (plastic)
   a pressure gauge
   a seat pack (for repair kit, wallet, keys, etc)
   gloves
   a water bottle and cage
   a lock
   
The shop can help you select these items and install them on your bike.


===========================================================================

Chains


Lubricating Chains

Lubricating chains is a somewhat religious issue.  Some advocate oil,
some Teflon-base lubricants, some paraffin wax.  The net majority favors
a lubricant that does not leave an oily coating on the chain that can
attract dirt, which will hasten chain/chainring/freewheel sprocket wear.

If you want to use paraffin wax, make sure you melt the wax in a double
boiler!  Failure to do so can lead to a fire.  You can use a coffee
can in a pan of boiling water if you don't want to mess up good cookware.
After the wax has melted, put the chain in the wax and simmer for 10
minutes or so.  Remove the chain, hang it up, and wipe the excess wax
off.  Let it cool and reinstall on your bike.

When using a liquid lubricant, you want to get the lube onto the pins
inside the rollers on the chains, not on the outside where it does little
good.  Oilers with the narrow tubes are good for this because you can put
the lube where you want it.  Work the oil into the chain after applying
it, wipe the chain off, and reinstall on your bike.

---------------------------------------------------------------------------

Wear and Gear Slippage  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

There seems to be a lot of speculation on what makes chains wear
and how to lubricate a chain.  There are a number of ways to take
care of a chain.  Some traditional methods are the most damaging
to chain life and others work to prolong life.

As was mentioned on the net, chains don't stretch in the sense
that the metal elongates, but the parts wear.  Wear in the pins
and sleeves change the length of the chain as the pins fit more
loosely.  The wear arises primarily from road grit that enters
the chain when it is oiled.  Grit on the outside of a chain looks
bad but it has no effect on the function because it can't get
inside to do damage.  Only when a dirty chain is oiled does this
grit get to the place where it can cause damage.  Note that
commercial abrasive grinding paste is made of oil and silicon
dioxide (sand) and silicon carbide (sand).  You couldn't do a
better job if you tried to destroy a chain than to oil a road
dirt (previously oiled) encrusted chain.

Primitive rule #1:  Never oil a chain on the bike.

This means you should clean the grit off the chain before oiling
it.  Because this is essentially impossible without submerging
the chain in a solvent bath (kerosene or commercial solvent), you
must take the chain off the bike.  The fine grit can only be
removed from the interior of the chain in liquid suspension.  A
good example of this can be seen by using a Vetta (on the bike)
chain cleaner and subsequently cleaning the same chain in a
solvent bath.  The best grit remains until last and there's
plenty of it.

Removing the solvent from the chain after the rinse is important.
Compressed air is not readily available in the household nor is a
centrifuge.  You can go outdoors and sling the chain around.
This works best if the chain is a closed loop.  You don't have to
press the pin completely in for this.  The other way is to
evaporate it.  You should probably avoid accelerated drying
methods because they could be explosive.

The hot gear lube method works but it also acts as efficient fly
paper, collecting plenty of grime between cogs.  Motor oil is good
but motorcycle chain lubes are better because they have volatile
solvents that allow good penetration for relatively viscous
lubricant.  Paraffin is useless because it is not mobile and
cannot replenish the bearing surface once it has been displaced.

Sedisport

The Sedisport chain, although the strongest and one of the
lightest chains, achieves its light weight at the expense of
durability.  This chain has omitted the sleeve that on most
roller chains supports the roller on its outside and furnishes
the bearing for the pin on the inside.  Normally the inside of
the sleeve is well protected against lubricant depletion because
both ends are covered by closely fitting side plates.  In the
Sedisport there is no sleeve and the formed side plates support
the roller and pin with a substantial central gap.  In the wet,
lubricant is quickly washed out of pin and roller and the inferior
bearing for the pin and roller often gall and bind.  In good
weather this is not a problem.  Because this chain has feet of
clay in the wet, Sedis re-introduced their earlier 5 element
conventional chain, calling it a "chain for all seasons".

The lightweight Regina chain goes one step farther and omits the
pin, leaving the side plates to hinge directly on the sleeve.
This gives them a knife edge bearing area that galls at the
slightest lube depletion.

Chain Life

This is almost entirely a cleanliness and lubrication question
rather than a load problem.  The effect of load variations is
insignificant when compared to the lube and grit effects for
bicycles.  The primary chains on motorcycles are operated under
clean conditions and last years while the exposed rear chains
must be replaced often.

The only way to test whether a chain is worn is by measurement.
The chain has a half inch pitch and, when new, has a pin at
exactly every half inch.  As the pins and sleeves wear this
spacing increases and becomes damaging to sprockets.  When the
chain pitch grows over one half percent it is time for a new
chain.  At one percent chainring damage progresses rapidly.  By
holding a ruler along the chain on your bile, align an inch mark
with a pin and see how far off the mark the pin is at twelve
inches.  An eighth of an inch (0.125) is the ten percent limit
while more than a sixteenth is a prudent time to get a new chain.

Skipping Chain

When you put on a new chain, its pitch is exactly one half inch.
A sprockets worn by a longer pitch chain pockets in its teeth.
These pockets are formed by the rollers of a worn chain as they
exit the sprocket under load.  Rollers of a new chain with
correct pitch exit under no load because the load is transferred
to the next roller before disengagement.  However, with hooked
sprockets the new chain cannot engage under load because the
pitch is too small to get over the hook and into the pocket.
These differences are only a few thousandths of an inch but that
is enough to prevent engagement when the previous roller is in
its pocket.

As a chain wears it concentrates more of its load on the last
tooth of a sprocket before disengagement because its pitch no
longer matches the pitch of the sprocket.  This effect sometimes
breaks off sprocket teeth.  The load concentration on the
sprocket also accelerates wear and is another reason to replace a
chain at 1/16th inch wear.

---------------------------------------------------------------------------

Adjusting Chain Length  (Bob Fishell  spike@cbnewsd.att.com)

For all Shimano SIS and Hyperglide systems, the chain is sized by shifting to
the smallest rear cog and the largest front sprocket, then sizing the
chain so that the derailleur pulleys are on a vertical line, or as close
as you can get to it.  Note that this will result in the same chain length
for any freewheel within the capacity of the derailleur, so it usually is
not necessary to re-size the chain for a different cogset with these systems.

The other rule I've used (friction systems) involves shifting to the largest
chainring and the largest rear cog, then sizing the chain so that the pulleys
are at a 45 degree angle to the ground.

The rules probably vary from derailleur to derailleur.  In general,
you may use the capacity of the rear derailleur cage as a guideline. You
want the chain short enough so the cage can take up the slack in the 
smallest combination of chainwheel and rear cog you will use. The chain
must also be long enough so that the cage still has some travel in the
largest combination you will use.

For example, if you have a 42x52 crank and a 13x21 freewheel, the smallest
combination you would use would be a 42/14 (assuming you don't use the
diagonal). If the cage can take up the slack in this combo, it's short enough.
If the cage has spring left when you are in the 52/19 combo (again, you are
not using the diagonal), it's long enough.

---------------------------------------------------------------------------

Hyperglide chains

When you need to replace a Shimano Hyperglide chain, use a Sedis ATB
chain.  It's compatible with the Hyperglide system and doesn't need
a special pin to put the chain back together when you take it apart.

===========================================================================

Cranks and Bottom Brackets

Bottom Bracket Info  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

The four kinds of BB threads in common use today are Italian, British,
French, and Swiss, possibly in that order of occurrence.

           Diameter   Pitch    Right Left Cup
           --------   -----    ----- -----
Italian    36mm   x   24F tpi  right right        tpi (threads per inch)
British    1.370" x   24F tpi  left  right
French     35mm   x   1mm      right right
Swiss      35mm   x   1mm      left  right

Unless there is something wrong with the right hand cup it should not be
removed but should be wiped clean and greased from the left side.  The
thread type is usually marked on the face of both left and right cups.
Swiss threads are rare but if you have one it is good to know before
attempting removal.

---------------------------------------------------------------------------

Crank noises  (Phil Etheridge  phil@massey.ac.nz)

I've had the creaky crank problem on every bike I've owned which has
had cotterless cranks.  Until now, I've never known a good solution to
the problem.  

One suggestion I had was to replace the crank, but that wasn't
something I was prepared to do on 1 month old bike under warranty. 
The shop mechanic spent half an hour with me and my bike sorting it
out.  Tightening the crank bolts and pedal spindle (i.e. onto the
crank) didn't help (as Jobst will tell you).  

Removing each crank, smearing the spindle with grease and replacing
the crank eliminated most of the noise.  Removing each pedal, smearing
grease on the thread and replacing it got rid of the rest of the
noise.

Greasing the pedal threads is a new one on me, but it makes a lot of
sense, since they are steel and the crank aluminum.  I thought it was
worth relating this story, as creaky cranks seems to be quite a common
problem.

---------------------------------------------------------------------------

Cracking/Breaking Crankarms  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

[Ed note:  Yes, another disputed issue is contained here - whether to
lube the crank tapers before installing the crankarms.  This has
popped up from time to time on rec.bicycles, and has never been
resolved one way or the other.  The text here is Jobst's viewpoint.]

Cranks break because they are aluminum and because they have high
stress at various points.  The worst of these points are at the
pedal eye and where the spider fingers join the right crank.  The
pedal eye is a bad place because the joint is incorrectly designed,
but since it is a standard, it may not be changed since it seems to
work.  This joint always moves and causes fretting corrosion and
cracks.  These cracks propagate into the crank and cause failure.
A better joint here would be a 45 degree taper instead of a flat
shoulder at the end of the pedal thread.

The thin web between the spider and crank, another common crack
origin on cranks like the Campagnolo Record, was nicely redesigned
in the C-Record crank, but to make up for that the C-Record is
otherwise weaker than the Record version.  My experience is that
they break in about 1500 miles because the pedal eye has a smaller
cross section than the Record model, but maybe the alloy is poorer
too.  I have subsequently used Dura Ace cranks for more than two
years with no failure yet.  I don't believe in eternal life here
either.

Aluminum has no safe fatigue limit but just gets progressively safer
as stress is reduced.  In contrast, steel has a threshold below
which failures cease.  Therein lies some of the problem.

As for cranks loosening, one can view the junction between spindle
and crank in an exaggerated elastic model where the spindle is made
of plastic and the crank of Rubbermaid household rubber.  The crank,
once properly installed and the retaining bolt in place, squirms on
the square taper when under torque.  During these deformations the
crank can move only in one direction because the bolt prevents it
from coming off.  The crank always slides farther up the taper.
Proof that the crank squirms is given by the fretting rouge always
found on the spindle, whether lubricated or not, when a crank is
pulled off after substantial use.

As was mentioned by various observers, the left crank bolt is
usually looser, after use, than the right one and this could be
anticipated because the two cranks differ in their loading.  This
does not mean the left crank is looser.  Actually it is tighter,
only the bolt is looser.  The left crank is more heavily loaded
because it experiences offset twist from the pedal at the same time
it transmits torque to the spindle.  The right crank, being
connected to the chain, experiences either spindle torque from the
left pedal or twist from the right pedal but not torque and twist at
the same time.

In this squirming mode, cranks wander away from the retaining bolt
and leave it loose after the first hard workout (for riders of more
than 150 lbs).  The bolts should NOT be re-tightened because they
were correctly tight when installed.  Cranks have been split in half
from repeated follow-up tightening, especially left cranks.  The
spindle should be lubricated before installing cranks.  A wipe of a
mechanic's finger is adequate since this is to prevent galling in
the interface.  To prevent losing a loose crank bolt, the "dust"
cover that is in fact the lock cap should be installed.

Those who have had a crank spindle break, can attest to the greater
stress on the left side because this is the end that always breaks
from fatigue.  A fatigue crack generally has a crystalline
appearance and usually takes enough time to develop that the face of
the fracture oxidizes so that only the final break is clean when
inspected.  Because a notch acts to concentrate stress, the
advancing crack amplifies this effect and accelerates the advance
once the crack has initiated.

I have heard of instructions to not lubricate spindles before
installing cranks but I have never been able to find it in any
manufacturer's printed material.  Although I have broken many
Campagnolo cranks, none has ever failed at the spindle.  I am
certain that the standard machine practice of lubricating a taper
fit has no ill effects.  I have also never had a crank come loose
nor have I re-tightened one once installed.

---------------------------------------------------------------------------

Biopace chainrings

Biopace chainrings have fallen into disfavor in recent years.  They
are hard to "pedal in circles".  The early Biopace chainrings were
designed for cadences of around 50-70 rpm, while most recommend a
cadence of 80-100 rpm.  Newer Biopace chainrings are less elliptical,
but the general consensus is to (if you are buying a new bike) get the
dealer to change the chainrings to round ones.

===========================================================================

Tires and tubes

Snakebite flats

Snakebite flats are usually caused by the tire and tube being pinched
between the road and the rim, causing two small holes in the tube that
look like a snakebite.  The usual causes are underinflation, too
narrow a tire for your weight, or hitting something (rock, pothole)
while having your full weight on the tire.

The obvious solutions are to make sure your tires are inflated properly,
use a larger size tire if you weigh a lot, and either avoid rocks and
potholes or stand up with your knees and elbows flexed (to act like shock
absorbers) when you go over them.

---------------------------------------------------------------------------

Blown Tubes  (Tom Reingold  tr@samadams.princeton.edu)

Charles E Newman writes:

$ 	 Something really weird happened at 12:11 AM. My bike blew a
$ tire while just sitting parked in my room. I was awakened by a noise
$ that scared the livin ^&$% out of me. I ran in and found that all the
$ air was rushing out of my tire. How could something like happen in the
$ middle of the night when the bike isn't even being ridden? I  have
$ heard of it happening when the bike is being ridden but not when it is
$ parked.

This happened because a bit of your inner tube was pinched between your
tire bead and your rim.  Sometimes it takes a while for the inner tube
to creap out from under the tire.  Once it does that, it has nothing to
keep the air pressure in, so it blows out.  Yes, it's scary.  I've had
it happen in the room where I was sleeping.

To prevent this, inflate the tire to about 20 psi and move the tire
left and right, making sure no part of the inner tube is pinched.

---------------------------------------------------------------------------

Mounting Tires   (Douglas Gurr  dgurr@daimi.aau.dk)

A request comes in for tyre mounting tricks. I suspect that this ought to be
part of the FAQ list. However in lieu of this, I offer the way it was taught
to me. Apologies to those for whom this is old hat, and also for the paucity
of my verbal explanations. Pictures would help but, as always, the best bet
is to find someone to show you.

First of all, the easy bit:

1) Remove the outer tyre bead from the rim. Leave the inner bead.
   Handy hint. If after placing the first tyre lever you
   are unable to fit another in because the tension in the bead is too great
   then relax the first, slip the second in and use both together.
2) Pull out the tube finishing at the valve.
3) Inspect the tube, find the puncture and repair it.

Now an important bit:

4) Check tyre for thorns, bits of glass etc - especially at the point where
   the hole in the tube was found.

and now a clever bit:

5) Inflate the tube a _minimal_ amount, i.e. just sufficient for it to
   hold its shape. Too much inflation and it won't fit inside the tyre.
   Too little (including none at all) and you are likely to pinch it.

More important bits:

6) Fit the tube back inside the tyre. Many people like to cover the tube in
   copious quantities of talcum powder first. This helps to lubricate
   the tyre/tube interface as is of particular importance in high pressure
   tyres.
7) Seat the tyre and tube over the centre of the rim.
8) Begin replacing the outer bead by hand. Start about 90 degrees away from
   the valve and work towards it. After you have safely passed the valve,
   shove it into the tyre (away from the rim) to ensure that you have
   not trapped the tube around the valve beneath the tyre wall.

Finally the _really_ clever bit:

9) When you reach the point at which you can no longer proceed by hand,
   slightly _deflate_ the tube and try again. Repeat this process until
   either the tyre is completely on (in which case congratulations)
   or the tube is completely deflated. In the latter case, you will have
   to resort to using tyre levers and your mileage may vary. Take care.

and the last important check:

10) Go round the entire wheel, pinching the tyre in with your fingers
    to check that there is no tube trapped beneath the rim. If you
    have trapped the tube, deduct ten marks and go back to step one.
    Otherwise ....

11) Replace wheel and reinflate.

---------------------------------------------------------------------------

More Flats on Rear Tires  (Jobst Brandt  jobst_brandt%01@hp1900.desk.hp.com)

Most sharp obstacles except tetrahedral glass slivers and puncture
vine gets stuck more often is that the front tire upsets the sharp
object just in time for the rear tire to catch it head-on. 

This front to rear effect is also true for motor vehicles.  Nails lying
on the road seldom enter front tires.  When dropped on the road by a
moving vehicle, the nail slides down the road aligning itself pointing
toward traffic because it tends to roll around until it is head first.
The tire rolls over it and tilts it up so that if the speed is ideal,
the rear tire catches it upright.  I once got a flat from a one inch
diameter steel washer that the rear tire struck on edge after the front
tire flipped it up.

When it is wet glass can stick to the tire even in the flat orientation
and thereby get a second chance when it comes around again.  To add to
this feature, glass cuts far more easily when wet as those who have cut
rubber tubing in chemistry class may remember.  A wet razor blade cuts
latex rubber tubing in a single slice while a dry blade only makes a
nick.

---------------------------------------------------------------------------

Anodized vs. Non-anodized Rims  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

There are several kinds of dark coatings sold on rims.  Each suggests that
added strength is achieved by this surface treatment while in fact no useful
effects other than aesthetic results are achieved.  The colored rims just
cost more as do the cosmetically anodized ones.  The hard anodized rims do
not get stronger even though they have a hard crust.  The anodized crust is
brittle and porous and crazes around spoke holes when the sockets are riveted
into the rim.  These cracks grow and ultimately cause break-outs if the
wheel is subjected to moderate loads over time.

There is substantial data on this and shops like Wheelsmith, that build many
wheels, can tell you that for instance, no MA-2 rims have cracked while MA-40
rims fail often.  These are otherwise identical rims.

Hard anodizing is also a thermal and electrical insulator.  Because heat is
generated in the brake pads and not the rim, braking energy must cross the
interface to be dissipated in the rim.  Anodizing, although relatively thin,
impedes this heat transfer and reduces braking efficiency by overheating the
brake pad surfaces.  Fortunately, in wet weather, road grit wears off the
sidewall anodizing and leaves a messy looking rim with better braking.

Anodizing has nothing to do with heat treatment and does not strengthen rims.
To make up for that, it costs more.

---------------------------------------------------------------------------

Clinchers vs. Tubulars  (F.J. Brown  F.Brown@massey.ac.nz)

D.H.Davis@gdt.bath.ac.uk gave some useful hints on mounting clinchers,
mostly involving the use of copious quantities of baby powder, and
trying to convince me that clinchers aren't difficult to mount, so ease of 
mounting isn't a valid reason for preferring tubulars.

wernerj@lafcol.lafayette.edu wrote that although average tubulars ride
'nicer' than average clinchers, there are some clinchers around that ride
just as 'nice'.   He also said that ease of change isn't a good reason for
preferring tubulars as if you flat in a race, you're either going to swap
a wheel or drop out.   He pointed out that tubulars end up costing $20 -
$80 per flat.

ershc@cunyvm.cuny.edu gave some of the historic reasons that tubulars were
preferred: higher pressures, lower weight, stronger, lighter rims.   Said
that only a few of these still hold true (rim strength/weight, total weight),
but he still prefers the 'feel' of tubulars.

leka@uhifa.ifa.hawaii.edu started this thread with his observations on 
clinchers seperated from their rims in the aftermath of a race crash.

stek@alcvax.pfc.mit.edu comments on improperly-glued tubulars posing a threat 
to other racers by rolling off, and noted that this couldn't happen with 
clinchers.

jobst_brandt@hplabs.hp.com agreed with stek, with the additional note that 
it is inadequate inflation that often allows tubulars to roll.

Kevin at Buffalo agreed with stek and jobst about tubulars (improperly or
freshly glued) sometimes rolling.

ruhtra@turing.toronto.edu says he uses clinchers for cost and convenience.
Clinchers let him carry around a tiny patch kit and some tyre irons, costing
60c, whereas tubulars would require him to carry a whole tyre, and would 
cost more.    

CONCLUSIONS: THE CLINCHER VS. TUBULAR WAR
Tubulars - used to be capable of taking higher pressures, had lower weight 
           and mounted onto stronger, lighter rims than clinchers.   Clinchers
           have now largely caught up, but many cyclists thinking hasn't.   
           Tubular tyre + rim combination still lighter and stronger.
         - are easier to change than clinchers.   This matters more to some 
           people than others - triathletes, mechanical morons and those 
           riding in unsupported races.
         - cost megabucks if you replace them every time you puncture.   
           ***However*** (and none of the North Americans mentioned this)
           down here in Kiwiland, we ***always*** repair our punctured
           tubulars (unless the casing is cut to ribbons).   The process
           doesn't take much imagination, you just unstitch the case, repair 
           the tube in the normal manner using the thinnest patches you can 
           buy, stitch it back up again and (the secret to success) put a
           drop of Superglue over the hole in the tread.
         - can roll off if improperly glued or inflated.   In this case, you
           probably deserve what you get.   Unfortunately, the riders behind
           you don't.

Clinchers - can be difficult to change (for mechanical morons) and are always
            slower to change than tubulars.   Most people still carry a spare
            tube and do their repairs when they get home.    
          - are cheaper to run: if you puncture a lot clinchers will probably 
            still save you money over tubulars, even if you repair your 
            tubulars whenever possible.   Tubulars are only repairable most 
            of the time, you virtually never write off a clincher casing due 
            to a puncture. 
          - have improved immensely in recent years; top models now inflate
            to high pressures, and are lighter and stronger than they used
            to be.   Likewise clincher rims.   Some debate over whether
            tubulars are still lighter and tubular rims stronger.   Probably
            depends on quality you select.   No doubt that high quality 
            clinchers/rims stronger, lighter and mor dependable than cheap
            tubular/rim combination.

---------------------------------------------------------------------------
Presta Valve Nuts  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

Two points here:

1. The jamb nut holds the stem when pumping so that it does not recede
   into the rim when pressing the pump head against the tire.  This is
   especially useful when the tire is flat (after installing the tube).
   It also keeps the stem from wiggling around while pumping.  I have
   not had difficulty in removing the nut over these many years of
   bicycling.  When hands are very cold this is a problem, but then so
   is everything else.  Just opening the valve nut on a Presta valve
   can be difficult under such conditions.

2. Breaking off stems while using a frame pump is a misunderstanding of
   the concept.  I find new tubes along the roadside with broken off
   stems.  The pump head is to be held in the fist and pumping force is
   supposed to be between the hands, not the hand and the rim.  To
   practice this action take the pump in hand with the thumb over the
   outlet and pump vigorously letting no air out.  No net force should
   escape since there is no other body involved.  This is essentially
   what should take place when pumping a tire.

   That the some of the people who do not grasp this concept have
   deficient thinking is proved by their discarding the evidence along
   the road.  They also have no concept of blatant littering for which
   there are large fines in this area.  They probably think it serves
   the stupid tube right for breaking off.  I think otherwise.  It is
   unfortunate that bike shops do not instruct new bike owners about the
   use of the frame pump and some tire patch hints like don't try to
   ride a freshly patches tube, carry a spare and always use the spare
   after patching the current tube.  I think we covered that extensively
   here earlier.  If it isn't in the FAQ it should be.

---------------------------------------------------------------------------
Ideal Tire Sizes  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

> I'm getting a custom frame built and wondered what
> people thought of using 26 inch road wheels.  Smaller
> wheels ought to be lighter and stronger.

and goes on to list advantages and disadvantages, most of which are less
that important in deciding what size to use.  What in fact brought us
the wheel size (700 or 27") that we have is better understood by the
women riders who have a hard time fitting these wheels into their small
bicycle frames.  Wheels would be larger than they are if they would fit
the average riders bike, but they don't.  So the compromise size is what
we are riding today.

> It seems to me that the most obvious reason for using 27"
> wheels is tradition, but I'm not sure the advantages make
> it worth trying to swim upstream.  What do you think?

This line of thought is consistent with the "cost be damned" approach
in bicycling today.  The big bucks are spent by people who want the best
or even better than their peers.  The more special the better.  Riders
consistently spend nearly twice the money for wheels and get worse rims
when they choose anodized ones, whether there is merit to this finish
is of no interest.  They cost more so they must be better.  How "custom"
can you get than to have wheels no one else on the block has (maybe 25"?).

If enough riders ask for 24", 25" and 26" wheels, manufacturers will up
the price as their product lines multiply and the total sales remain
constant.  Tires and spokes will follow as a whole range of sizes that
were not previously stocked become part of the inventory.  Meanwhile,
bike frames will come in different configurations to take advantage of
the special wheel sizes.  SIzes whose advantages are imperceptibly small
but are touted by riders who talk of seconds saved in their last club TT
or while riding to work.

A larger wheel rides better on average roads and always corners better
because it brings a longer contact patch to the road.  A longer contact
averages traction over more pavement and avoids slip outs for lack of
local traction.  Visualize crossing a one inch wide glossy paint stripe
with a 27" wheel and an 18" wheel when banked over in a wet turn.

I see this subject arise now and then and it reminds me of the concept of
splitting wreck.bike into several newsgroups.  The perpetrators bring the
matter up for many of the wrong reasons.

Ride bike, don't re-invent what has been discarded.

===========================================================================

Headsets, Forks

Indexed Steering  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

> In the several years I spent working in a pro shop, I have never seen a
> case of "index steering" (yes, we called it that) that was _not_ caused
> by a "brinelled" headset - one with divots in the races.  I am 99.999
> percent certain that that is your problem.  What are you going to do if
> you don't fix it?  I suggest that you fix the headset even if you sell
> the bike, as a damaged headset could be grounds for a lawsuit if the
> buyer crashes.

I disagree on two points.  First, because the use of the term brinelling
conveys a notion as incorrect as the phrase "my chain stretched from
climbing steep hills" and second, because there is no possibility of
injury or damage from an "indexed" head bearing.

Damage to the head bearings seems to be twofold in this case because the
steering, if properly adjusted, only gets looser from dimpled bearings and
would not become arrested by the dimples.  So the head was adjusted too
tight or it got tighter inadvertently.  However, dimpling is caused by
lubrication failure and occurs while riding straight ahead.  This condition
is worsened by a tight bearing while a loose bearing would introduce more
lubricant if it were to rattle.

If you believe it comes from hammering the balls into the races, I suggest
you try to cause some dimples by hammering with a hammer onto the underside
of the fork crown of a clunker bike of your choice.  Those who pounded in
cotters on cottered cranks will recall no such dimpling on the BB axle and
even though this is a far smaller bearing race than a head bearing and the
blows are more severe and direct, no dimples were made.

Ball bearings make metal-to-metal contact only when subjected to fretting loads
(microscopic oscillations) while in the same position, as in riding straight
ahead on a conventional road.  If you watch your front axle while rolling
down the road at 20+ mph you will notice that the fork ends vibrate fore and
aft.  This motion arises not at the blade tips but at the fork crown and
articulates the head bearing in fretting motions that are not in the normal
direction of bearing rotation.  Any substantial steering motion replenishes
lubrication from adjoining areas.

Lubrication failure from fretting causes welding between the balls and
races and these tiny weld spots tear out repeatedly.  The result is that at
the front and rear of the races elliptical milky dimples occur.  Were these
brinelling (embossed through force) they would be shiny and round.  Various
testimonials for the durability of one bearing over another may be based on
good experience, however, the differences in most of these was not in the
design of the bearing but rather the type of lubricant used.  A ball bearing
is not suitable for this use.  This is in spite of their use in almost all
bicycles.

To reduce point loads and to protect the rolling elements from fretting
motion, roller bearing head bearings have been built.  In these the rotary
motion is taken up in needle bearings on conical races and the fork
articulation is absorbed by an approximation of a spherical cup (the steel
race) against the aluminum housing.  Both of these bearings are ideally
loaded.  The rollers all remain in contact and carry rotary motion while
the plain spherical bearing remains in full contact carrying low pressure
fore and aft motion.

I am disappointed that roller bearings until now have not been suitably
perfected to rid us of the age old bearing failure.  Maybe some day soon
Sun Tour, Campagnolo, Shimano or Stronglight will emerge with an easily
adjustable and fully compatible bearing.  The one I am using is durable but
not easily adjusted and it has too great a stack height to qualify for a
recommended replacement.

===========================================================================

Brakes

Center Pivot vs. Dual Pivot Brakes  (Jobst Brandt  jobst_brandt@hplabs.hp.com)

Sidepull (one central pivot) brakes operate at a small angle to the
rim.  That means the pad moves in a nearly perpendicular direction to
the braking surface and the pads can be completely worn down without
adjusting their position.  The unit is light and has a self contained
quick release and cable adjustment feature.

Its weakness is its thin arms that, in the pursuit of light weight,
flex in the bending direction.  With the current practice to minimize
tire clearance on road bicycles, sidepull brakes cannot be used off
road for lack of dirt clearance.  Their return spring is anchored in a
way that relative motion occurs between it and the brake arms.  This
motion demands lubrication and in its absence the brake does not
center itself.  This is a perpetual problem that has not been solved
and has given rise to many designs, the latest of which is the Shimano
dual pivot brake.  This brake has the disadvantage that it cannot
track a wobbly wheel because it is forced to be centered.

The cantilever and centerpull brakes are inversions of the same
design.  Both have pivot points that are at 45 degrees to the brake
surface, but the centerpull offers no advantage over sidepulls because
it has all the same problems and not the advantages.  In contrast the
cantilever is the most rigid of available brakes and offers more tire
clearance for off road use.

The approach angel moves the brake pads in an undesirable direction so
that as the pad wears it must be adjusted to prevent falling off the
rim.  With wear, the centerpull goes into the tire while the
cantilever allows the pad to pop under the rim, never to return.
Cantilever brakes have the additional problem that their reaction
force spreads the forks.  For this reason, U shaped stress plates are
made to contain this force.  For forks with telescopic suspension,
braking restricts forks motion.

Nearly all bicycle brakes have about the same mechanical advantage
(4:1) that arises primarily in the hand lever.  The "calipers" all
approximate a 1:1 ratio.  This is necessary to fit the reach of the
average hand and the strength of the hand in proportion to body
weight.  That is to say all brakes are made to about the same human
specification.  Force and motion are a trade-off and this is the
result.

The Campagnolo Delta and Modolo Chronos brakes have a variable ratio
that at the extremes ranges from infinity to zero, its motion being
generated by an equilateral parallelogram that changes from one
extreme to the other.  This is an undesirable feature, especially as
the pads wear and braking takes place in the zone of increased lever
travel and increased mechanical advantage.  The brake bottoms out
abruptly.

Servo activation on cantilever brakes has been offered in a design that
uses the forward thrust on the brake post to add force to the
application.  Self servo effects are undesirable in brakes because the
proportionality between braking and hand force is lost.  You don't
know how much braking you will get for a given hand lever force.  It
can vary widely and in some circumstances cause an unwanted skid.

===========================================================================

Adjustments and Repairs

Seat adjustments   (Roger Marquis  marquis@well.sf.ca.us)

     The following method of setting saddle height is not the
only method around for setting your saddle height but it is the
most popular among coaches and riders both here and in Europe.
 
     A) Adjust saddle level or very slightly nose up, no more
        than 2mm at the nose.
     B) Put on the shoes you normally ride in. Have wrench ready
        (usually a 5mm Allen).
     C) Mount the bike and sit comfortably, leaning against a
        wall. Hold the brake on with one hand (or mount the bike
        on a turbo trainer if you have one).
     D) Place your HEELS on the pedals, opposite the clip, pedal
        backwards at 30+ rpm without rocking your pelvis (very
        important).
     E) Adjust seat height so that there is about:
      1) ZERO TO ONE HALF CM. for recreational riders
         (-50 mi/wk.),
      2) ONE HALF TO ONE CM. for experienced riders
         (50+ mi./wk.),
      3) ONE TO TWO CM. for endurance cyclists (250+ mi./wk.),
         between your heel and the pedal. If your soles are
         thicker at the cleat than at the heel adjust accordingly.
        Don't forget to grease the seat post.
     F) Ride. It may take a couple of rides to get used to the
        feel and possibly stretch the hamstrings and Achilles
        slightly.
 
---------------------------------------------------------------------------

Cleat adjustments   (Roger Marquis  marquis@well.sf.ca.us)

[Ed note:  You may also want to consider going to a bike shop that does
Fit Kit and have them do the Fit Kit RAD to adjust your cleats.  Many
people recommend it.]

     A) Grease the cleat bolts and lightly tighten.
     B) Sitting on the bike, put your feet in the pedals and
        adjust until:
     B1) The ball of your foot is directly above or, more         
         commonly, slightly behind the pedal axle and:
     B2) There is approximately 1 cm. (1/2in.) between your ankle
         and the crank arm.
     C) Tighten the cleat bolts 80% and go out for a ride.
        If another position feels more comfortable rotate
        your foot into that position.
     D) Carefully remove your shoes from the pedals and tighten
        the bolts fully. If you cannot get out of the pedals
        without shifting the cleats leave your shoes on the bike
        and draw an outline around the cleat.

---------------------------------------------------------------------------

SIS Adjustment Procedure  (Bob Fishell  spike@cbnewsd.att.com)

Shimano's instructions for adjusting SIS drivetrains varies from series
to series.  The following method, however, works for each of mine (600EX,
105, and Deore').  [Ed note:  Works on Exage road and mtb also.]

Your chain and cogs must be in good shape, and the cable must be free
of kinks, slips,  and binds.  The outer cable should have a liner.
clean and lubricate all points where the cable contacts anything.

SIS adjustment:

1) Shift the chain onto the largest chainwheel and the smallest cog,
   e.g., 52 and 13.

2) WITHOUT TURNING THE CRANKS, move the shift lever back until it
   clicks, and LET GO.  This is the trick to adjusting SIS.

3) Turn the crank.  If the chain does not move crisply onto the next
   inside cog, shift it back where you started, turn the SIS barrel
   adjuster (on the back of the rear derailleur) one-half turn CCW,
   and go back to step 2.  Repeat for each pair of cogs in turn
   until you can downshift through the entire range of the large
   chainwheel gears without the chain hesitating.  If you have just
   installed or reinstalled a shift cable, you may need to do this
   several times.

4) Move the chain to the small chainring (middle on a triple) and the 
   largest cog.

5) turn the cranks and upshift.  If the chain does not move crisply
   from the first to the second cog, turn the SIS barrel adjuster
   one-quarter turn CW.

If the drivetrain cannot be tuned to noiseless and trouble-free
SIS operation by this method, you may have worn cogs, worn chain,
or a worn, damaged, or obstructed shift cable.  Replace as needed
and repeat the adjustment.

===========================================================================

Tools and Workstands

Where to buy tools

You can buy tools from many sources.  Some tools can be purchased at
your local hardware store (wrenches, socket sets, etc), while the
special bike tools can be purchased from your local bike store or
one of the mail order stores listed elsewhere.

You can buy every tool you think looks useful, or just buy the tools
you need for a particular repair job.  Buying the tools as you need
them will let you build up a nice tool set over time without having
to drop a lot of money at once.

Some common tools you will need are:

  Metric/SAE wrenches for nuts and bolts (or an assortment of adjustable
    wrenches).
  Screwdrivers, both flat and phillips.
  Metric allen wrenches.
  Pliers.
  Wood or rubber mallet for loosening bolts.

Special tools and their uses:

  Cone wrenches to adjust the hub cones.
  Chain tool to take the chain apart for cleaning and lubrication, and
    to put it back together.
  Tire irons for removing tires.
  Spoke wrenches for adjusting spokes.
  Cable cutters for cutting cables (don't use diagonal pliers!).
  Crankarm tools for removing crankarms.
  Bottom bracket tools for adjusting bottom brackets.
  Headset wrenches to adjust the large headset nut.
    
---------------------------------------------------------------------------

Workstands

There are a variety of workstands available, from about $30 to over
$130.  Look at the mail order catalogs for photos showing the different
types.  The type with a clamp that holds one of the tubes on the bike
are the nicest and easy to use.  Park has a couple of models, and their
clamp is the lever type (pull the lever to lock the clamp).  Blackburn
and Performance have the screw type clamp (screw the clamp shut on the
tube.

If you have a low budget, you can use two pieces of rope hanging from 
the ceiling with rubber coated hooks on the end - just hang the bike
by the top tube.  This is not as steady as a workstand, but will do
an adequate job.

===========================================================================

Riding Techniques

Descending I  (Roger Marquis  marquis@well.sf.ca.us)

     Descending ability, like any other skill, is best improved 
with practice. The more time you can spend on technical descents 
the more confidence and speed you will be able to develop. A few 
local hot shots I know practice on their motorcycles before races 
with strategic descents. While frequent group rides are the only 
way to develop real bike handling skills descending with others 
will not necessarily help you descend faster alone.

     The most important aspect of fast descending is relaxation. 
Too much anxiety can narrow your concentration and you will miss 
important aspects of the road surface ahead. Pushing the speed to 
the point of fear will not help develop descending skills. Work 
on relaxation and smoothness (no sudden movements, braking or 
turning) and the speed will follow.

     A fast descender will set up well in advance of the corner 
on the outside, do whatever braking needs to be done before 
beginning to turn, hit the apex at the inside edge of the road, 
finally exiting again on the outside (always leaving some room 
for error or unforeseen road hazard). The key is to _gradually_ 
get into position and _smoothly_ follow your line through the 
corner. If you find yourself making _any_ quick, jerky movements 
take them as a sign that you need to slow down and devote a 
little more attention further up the road.

     Use your brakes only up to the beginning of a corner, NEVER 
USE THE BRAKES IN A CORNER. At that point any traction used for 
braking significantly reduces the traction available for 
cornering. If you do have to brake after entering the curve 
straighten out your line before applying the brakes. If the road 
surface is good use primarily the front brake. If traction is 
poor switch to the rear brake and begin breaking earlier. In auto 
racing circles there are two schools of thought on braking 
technique. One advocates gradually releasing the brakes upon 
entering the corner, the other advises hard braking right up to 
the beginning of the curve and abruptly releasing the brakes just 
before entering the curve. A cyclists would probably combine the  
techniques depending on the road surface, rim trueness, brake pad 
hardness and the proximity of other riders.

     Motorcyclists and bicyclists lean their bikes very 
differently in a corner. When riding fast motorcyclists keep 
their bikes as upright as possible to avoid scraping the bike. 
Bicyclists on the other hand lean their bikes into the corner and 
keep the body upright. Both motorcyclists and bicyclists extend 
the inside knee down to lower the center of gravity. To _pedal_ 
through the corners make like a motorcyclists and lean the bike 
up when the inside pedal is down. 

     One of the most difficult things about descending in a group 
is passing. It is not always possible to begin the descent ahead 
of anyone who may be descending slower. If you find yourself 
behind someone taking it easy either hang out a safe distance 
behind or pass very carefully. Passing on a descent is always 
difficult and dangerous. By the same token, if you find yourself 
ahead of someone who obviously wants to pass, let them by at the 
earliest safe moment. It's never appropriate to impede someone's 
progress on a training ride whether they are on a bicycle or in a 
car. Always make plenty of room for anyone trying to pass no 
matter what the speed limit may be. Be courteous and considerate 
and you'll be forever happy. 

     Remember that downhill racing is not what bicycle racing is 
all about. There is no need to keep up with the Jones'. This is 
what causes many a crash. Compete against yourself on the 
descents. Belgians are notoriously slow descenders due to the 
consistently rainy conditions there. Yet some of the best 
cyclists in the world train on those rainy roads. Don't get 
caught pushing it on some wet or unfamiliar descent. Be prepared 
for a car or a patch of dirt or oil in the middle of your path 
around _every_ blind corner no matter how many times you've been 
on a particular road. Take it easy, relax, exercise your powers 
of concentration and hammer again when you can turn the pedals. 

     If you're interested in exploring this further the best book 
on bike handling I've read is "Twist of The Wrist" by motorcycle 
racer Keith Code. There is also data out there (Cycle Magazine) 
on eye exercises designed to train depth perception adjustment, 
peripheral vision and concentration. If you know where I can   
find this information please send it to:

     NCNCA District Coaching Office
     Roger Marquis
     782 San Luis Rd.
     Berkeley, Ca 94707

Newsgroups: rec.bicycles.misc