Internet Info 1994 March/Internet Info CD-ROM (Walnut Creek) (March 1994).iso/answers/rec/bicycles-faq/part3

Internet Message Format | 1994-03-19 | 70KB

Path: bloom-beacon.mit.edu!hookup!swrinde!ihnp4.ucsd.edu!news.service.uci.edu!draco.acs.uci.edu!iglesias
From: [e-mail] (Mike Iglesias)
Newsgroups: rec.bicycles.misc,news.answers,rec.answers
Subject: Rec.Bicycles Frequently Asked Questions Posting  Part 3/5
Supersedes: <[e-mail]>
Followup-To: rec.bicycles.misc
Date: 19 Mar 1994 17:41:35 GMT
Organization: University of California, Irvine
Lines: 1428
Approved: [e-mail]
Distribution: world
Expires: 20 Apr 94 00:00:00 GMT
Message-ID: <[e-mail]>
References: <[e-mail]>
NNTP-Posting-Host: draco.acs.uci.edu
Originator: [e-mail]
Xref: bloom-beacon.mit.edu rec.bicycles.misc:14242 news.answers:16562 rec.answers:4499

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.]

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

Cracking/Breaking Cranks  (Jobst Brandt  [e-mail])

[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.

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

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  [e-mail])

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  [e-mail])

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  [e-mail])

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.

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

What holds the rim off the ground?  (Jobst Brandt  [e-mail])

> What forces keep the rim of a wheel with pneumatic tires off the
> ground. It obviously can't be the air pressure because that's acting
> from top as well as from below.

As has been pointed out, the casing walls pull on the rim (or its
equivalent) and thereby support the load.  The casing leaves the rim
at about a 45 degree angle, and being essentially a circular cross
section, it is in contact with the rim over its inner quarter circle.
At least this is a good representative model.  The visualization may
be simpler if a tubular tire is considered.  It makes no difference
whether the tire is held on by glue or is otherwise attaches to the
rim such as a clincher is.  Either way the tire is attached to the
rim, a relatively rigid structure.

Under load, in the ground contact zone, the tire bulges so that two
effects reduce the downward pull (increase the net upward force) of
the casing.  First, the most obvious one is that the casing pulls more
to the sides than downward (than it did in its unloaded condition);
the second is that the side wall tension is reduced.  The reduction
arises from the relationship that unit casing tension is equivalent to
inflation pressure times the radius of curvature divided by pi.  As
the curvature reduces when the tire bulges out, the casing tension
decreases correspondingly.  The inflated tire supports the rim
primarily by these two effects.

Tire pressure changes imperceptibly when the tire is loaded because
the volume does not change appreciably.  Besides, the volume change is
insignificant in small in comparison to the volume change the air has
undergone when being compressed into the tire.  In that respect, it
takes several strokes of a frame pump to increase the pressure of a
tire from 100 psi to 101.  The air has a low spring constant that acts
like a long soft spring that has been preloaded over a long stroke.
Small deflections do not change its force materially.  For convenience
car and truck tires are regularly inflated to their proper pressure
before being mounted on the vehicle.

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

Anodized vs. Non-anodized Rims  (Jobst Brandt  [e-mail])

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.

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

Reusing Spokes  (Jobst Brandt  [e-mail])

>I just bent my wheel and am probably going to need a new one
>built.  Can I reuse my old, 3 months, spokes in the new wheel.
>The guy at the shop gave me some mumbo jumbo about tensioning or
>something.

There is no reason why you should not reuse the spokes of your
relatively new wheel.  The reason a bike shop would not choose to do
this is that they do not know the history of your spokes and do not
want to risk their work on unknown materials.  If you are satisfied
that the spokes are good quality you should definitely use them for
you new wheel.  The spokes should, however, not be removed from the
hub because they have all taken a set peculiar to their location, be
that inside or outside spokes.  The elbows of outside spokes, for
instance, have an acute angle while the inside spokes are obtuse.

There are a few restrictions to this method, such as that new rim
must have the same effective diameter as the old, or the spokes will
be the wrong length.  The rim should also be the same "handedness"
so that the rim holes are offset in the correct direction.  This is
not a fatal problem because you can advance the rim one hole so that
there is a match.  The only problem is that the stem will not fall
between parallel spokes as it should for pumping convenience.

Take a cotton swab and dab a little oil in each spoke socket of the
new rim before you begin.  Hold the rims side by side so that the
stem holes are aligned and note whether the rim holes are staggered
in the same way.  If not line the rim up so they are.  Then unscrew
one spoke at a time, put a wipe of oil on the threads and engage it
in the new rim.  When they are all in the new rim you proceed as you
would truing any wheel.  Details of this are in a good book on
building wheels.

The reason you can reuse spokes is that their failure mode is
fatigue.  There is no other way of causing a fatigue failure than to
ride many thousand miles (if your wheel is properly built).  A crash
does not induce fatigue nor does it even raise tension in spokes
unless you get a pedal between them.  Unless a spoke has a kink that
cannot be straightened by hand, they can all be reused.

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

Clinchers vs. Tubulars  (F.J. Brown  [e-mail])

[e-mail] 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.

[e-mail] 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.

[e-mail] 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.

[e-mail] started this thread with his observations on
clinchers seperated from their rims in the aftermath of a race crash.

[e-mail] comments on improperly-glued tubulars posing a threat
to other racers by rolling off, and noted that this couldn't happen with
clinchers.

[e-mail] 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.

[e-mail] 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  [e-mail])

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.
   Removing the nut should present no difficulty unless the threads
   have been damaged or the hands are cold.  The cold may present a
   problem, but then just opening the valve nut on a Presta valve
   under such conditions.

2. Breaking off stems with a frame pump comes from pumping
   incorrectly.  The number of new tubes with broken stems lying along
   the road proves that this occurs far too often.  To avoid breaking
   the stem, the pump head should be be held in the fist so that the
   pumping force goes from one hand into the other, not from the pump
   into the valve stem.  To practice the correct action, hold the pump
   head in one hand with the thumb over the outlet, and pump
   vigorously letting out no air.  All the force goes from one hand
   into the other.  This is essentially what should take place when
   inflating a tire.

   It does no good to "get even" with the stupid tube by discarding it
   on the road for all to see.  Most riders understand how to pump a
   tire and see this only as evidence of incompetence rather than a
   faulty tube.  Besides, this ostentatious behavior constitutes
   littering for which the the fine is $1000 in California.  Bike
   shops should instruct new bike owners about the use of the frame
   pump.  Along with this there should be some tire patch hints like
   don't try to ride a freshly patched tube, carry a spare tube and
   always use the spare after patching the punctured tube.  Of course
   this is a whole subject in itself that should be treated under its
   own heading.

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

Ideal Tire Sizes  (Jobst Brandt  [e-mail])

> 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.

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

Indexed Steering  (Jobst Brandt  [e-mail])

> 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.

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

Center Pivot vs. Dual Pivot Brakes  (Jobst Brandt  [e-mail])

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.

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

Seat adjustments   (Roger Marquis  [e-mail])

     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  [e-mail])

[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  [e-mail])

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.

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

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.

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

Workstands 2  (Douglas B. Meade  [e-mail])

    >>>>>>>>>>      BICYCLE REPAIR STAND SUMMARY      <<<<<<<<<<

The Park PRS6 was recommended by several (>5) responders; all
other models were recommended by no more than one responder.

    Park PRS6
        PROS:    full 360\degree rotation
            spring-loaded clamp is adjustable
            very stable
        CONS:    not height adjustable
            not easy to transport
            clamp probably can't work with fat-tubed mtn bike
        COST:    ~$150
        SOURCE:    catalogs, local bike shops

    Park Consumer
        PROS:    foldable
            convenient
            portable
        CONS:    not as stable as PRS6
        COST:    ~$100
        SOURCE:    catalogs, local bike shops

    Park BenchMount
        PROS:    stronger, and more stable, than many floor models
        CONS:    must have a workbench with room to mount the stand
        COST:    $???
        SOURCE:    ???

    Blackburn
        PROS:    The stand folds flat and is portable.
            It has a 360 degree rotating clamp.
            It is relatively stable.
        CONS:    crank-down clamp does not seem to be durable
            crank bolt is not standard size; difficult to replace
            hard to get clamp tight enough for stable use
            clamp scratchs paint/finish
            problems getting rotating mechanism to work properly
        COST:    ~$100
        SOURCE:    catalogs, local bike shops

    Performance
        PROS:
        CONS:    not too stable

    Ultimate Repair Stand
        PROS:    excellent quality
            includes truing stand
            includes carrying bag
        CONS:
        COST:    ~$225
        SOURCE:    order through local bike shop
            the U.S. address for Ultimate Support Systems is :
                Ultimate Support Systems
                2506 Zurich Dr.
                P.O. Box 470
                Fort Collins, CO. 80522-4700
                Phone [phone]

I also received three homemade designs. The first is quite simple:

    hang the bike from coated screw hooks
        (available in a hardware store for less that $5/pair)

The others are more sophisticated. Here are the descriptions provided
by the designers of the systems.

Dan Dixon <[e-mail]> describes a modification
of the Yakima Quickstand attachment into a freestanding workstand

    I picked up the Yakama clamp and my local Bike shop for
    around $25.  What you get is the clamp and a long carraige
    bolt with a big (5") wing nut. This is meant to be attached
    to their floor stand or their roof racks. The roof rack
    attachment is ~$60; expensive, but great for road trips.

    I, instead, bought a longer carraige bolt, a piece of
    3/4" threaded lead pipe, two floor flanges, and some 2x4's.
    (about $10 worth of stuff).

    You say you want to attach it to a bench (which should be easy)

                                      pipe
                      +- clamp        |            wing nut
                      |               |            |
                      V               |      +--+  V
                 | |---------+        V      |  |   O
                 | |         | |\_________/| |  |  /
                 | |   -O-   |=| _________ |=|  |==I
                 | |         | |/         \| |  |  \
                 | |---------+               |  |   O
                                             |  |
                                /\       /\  |  |<-2x4
                                |         |  |  |
                       flanges--+---------+  |  |
                                             |  |

    Excuse the artwork, but it might give you and Idea about
    what I mean. You could just nail the 2x4 to the bench or
    something. I really like the clamp because it is totally
    adjustable for different size tubes.

Eric Schweitzer <[e-mail]> prefers the following
set-up to the Park `Professional' stands that he also has.

    My favorite 'stand', one I used for many years, one that I
    would use now if my choice of stand were mine, is made very
    cheaply from old seats and bicycle chain. Two seats (preferably
    cheap plastic shelled seats) (oh...they must have one wire
    bent around at the front to form the seat rails...most seats
    do) have the rails removed and bent to form 'hooks'. The
    'right' kind of hooks are placed in a good spot on the ceiling
    about 5 or 6 feet apart. (really, a bit longer than the length
    of a 'typical' bike from hub to hub. If you do a lot of tandems
    or LWB recombants, try longer :) Form a loop in one end of the
    chain by passing a thin bolt through the opening between 'outer'
    plates in two spots on the chain. (of course, this forms a loop
    in the chain, not the bolt). The same is done at the other end
    to form loops to hold the seat rail/hooks. First, form the hooks
    so they form a pair of Js, about 2 inch 'hook's The hook for the
    front of the bike is padded, the one for the rear looped through
    the chain, squeezed together to a single hook, and padded.

    To use, hook the rear hook under the seat, or at the seat stays.
    Hook the front with each arm on oposite sides of the stem. Can
    also hook to head tube (when doing forks). Either hook can grab
    a rim to hold a wheel in place while tightening a quick release
    skewer or axle bolt. There is no restricted access to the left
    side of the bike. I try to get the BB of a 'typical' frame about
    waist height.

In closing, here is a general statement that only makes my decision
more difficult:

    My best advice is to consider a workstand a long term durable good.
    Spend the money for solid construction. Good stands don't wear or
    break, and will always be good stands until the day you die, at
    which point they will be good stands for your children. Cheese will
    always be cheese until it breaks.

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

Frame Stiffness  (Bob Bundy  [e-mail])

As many of you rec.bicycles readers are aware, there have been occasional,
sometimes acrimonious, discussions about how some frames are so much
stiffer than others.  Cannondale frames seem to take most of the abuse.
The litany of complaints about some bike frames is long and includes
excessive wheel hop, numb hands, unpleasant ride, broken spokes,
pitted headsets, etc.  I was complaining to a friend of mine about how there
was so much ranting and raving but so little empirical data - to which
he replied, "Why don't you stop complaining and do the measurements
yourself?".  To that, I emitted the fateful words, "Why not, after all,
how hard can it be?".  Following some consultation with Jobst and a few
other friends, I ran the following tests:

The following data were collected by measuring the vertical deflection at
the seat (ST), bottom bracket (BB) and head tube (HT) as a result of
applying 80lb of vertical force.  The relative contributions of the
tires, wheels, fork, and frame (the diamond portion) were measured using
a set of jigs and a dial indicator which was read to the nearest .001
inch.  For some of the measures, I applied pressures from 20 to 270 lbs
to check for any significant nonlinearity.  None was observed.  The same
set of tires (Continentals) and wheels were used for all measurements.
Note that these were measures of in-plane stiffness, which should be
related to ride comfort, and not tortional stiffness which is something
else entirely.

Bikes:

TA - 1987 Trek Aluminum 1200, this model has a Vitus front fork, most
     reviews describe this as being an exceptionally smooth riding bike

SS - 1988 Specialized Sirus, steel CrMo frame, described by one review as
     being stiff, hard riding and responsive

DR - 1987 DeRosa, SP/SL tubing, classic Italian road bike

RM - 1988 Cannondale aluminum frame with a CrMo fork, some reviewers
      could not tolerate the rough ride of this bike


               TA              SS              DR              RM
           ----------      ----------      ----------      ----------
       ST  BB  HT      ST  BB  HT      ST  BB  HS      ST  BB  HT
diamond        1   1   0       2   2   0       2   2   0       1   1   0
fork        3  11  45       3   9  36       4  13  55       3  10  40
wheels      2   2   2       2   2   2       2   2   2       2   2   2
tires      68  52  66      68  52  66      68  52  66      68  52  66
total      74  66 113      75  65 104      76  69 123      74  65 108


What is going on here?  I read the bike mags and this net enough to know
that people have strong impressions about the things that affect ride
comfort.  For example, it is common to hear people talk about rim types
(aero vs. non-aero), spoke size, butting and spoke patterns and how they
affect ride.  Yet the data presented here indicate, just a Jobst predicted,
that any variation in these factors will essentially be undetectable to
the rider.  Similarly, one hears the same kind of talk about frames,
namely, that frame material X gives a better ride than frame material Y, that
butted tubing gives a better ride that non-butted, etc.  (I may have even
made such statements myself at some time.)  Yet, again, the data suggest
that these differences are small and, perhaps, even undetectable.  I offer
two explanations for this variation between the data and subjective reports
of ride quality.

Engineering:
These data are all static measurements and perhaps only applicable at the
end of the frequency spectrum.  Factors such as frequency response, and
damping might be significant factors in rider comfort.

Psychology:
There is no doubt that these bikes all look very different, especially the
Cannondale.  They even sound different while riding over rough
roads.  These factors, along with the impressions of friends and reviews
in bike magazines may lead us to perceive differences where they, in fact,
do not exist.

Being a psychologist, I am naturally inclined toward the psychological
explanation.  I just can't see how the diamond part of the frame contributes
in any significant way to the comfort of a bike.  The damping of the frame
should be irrelevant since it doesn't flex enough that there is any
motion to actually dampen.  That the frame would become flexible at
some important range of the frequency spectrum doesn't seem likely either.

On the other hand, there is plenty of evidence that people are often very
poor judges of their physical environment.  They often see relationships
where they don't exist and mis-attribute other relationships.  For example,
peoples' judgement of ride quality in automobiles is more related to the
sounds inside the automobile than the ride itself.  The only way to get
a good correlation between accelerometers attached to the car seat and
the rider's estimates of ride quality is to blindfold and deafen the
rider (not permanently!).  This is only one of many examples of mis-
attribution.  The role of expectation is even more powerful.  (Some even
claim that whole areas of medicine are built around it - but that is
another story entirely.)   People hear that Cannondales are stiff and,
let's face it, they certainly *look* stiff.  Add to that the fact that
Cannondales sound different while going over rough roads and perhaps
the rider has an auditory confirmation of what is already believed to
be true.

Unless anyone can come up with a better explanation, I will remain
convinced that differences in ride quality among frames are more a
matter of perception than of actual physical differences.

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

Frame materials

[Ed note: I got this information from some of the books I have.  People
in the know are welcome to update this.]

There are several materials that are used to make bicycle frames.  They
are:

  Mild steel - usually used in cheap department store bikes.  Frames
               made from mild steel are heavy.

  High carbon steel - a higher quality material used in low end bikes.
               Reynolds 500 is an example.

  Steel alloy - lighter and better riding than high-carbon frames.  Reynolds
               501 and Tange Mangaloy are examples.

  Chro-moly -  also called chrome-molybdenum or manganese-molybdenum steel.
               One of the finest alloys for bike frames.  Reynolds 531 and
               Columbus SL and SP are some of the best known brands.

  Carbon fiber - high tech stuff.  Made from space-age materials, frames
               made of this are very light and strong.  Some problems
               have been seen in the connections between the tubes and
               bottom bracket, etc.

  Aluminum -   Light frames, usually with larger diameter tubes.
               Cannondale is a well-known brand.

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

Bike pulls to one side  (Jobst Brandt  [e-mail])

For less than million dollar bikes this is easy to fix, whether it corrects
the cause or not.  If a bike veers to one side when ridden no-hands, it
can be corrected by bending the forks to the same side as you must lean
to ride straight.  This is done by bending the fork blades one at a time,
about 3 mm.  If more correction is needed, repeat the exercise.

The problem is usually in the forks although it is possible for frame
misalignment to cause this effect.  The kind of frame alignment error
that causes this is a head and seat tube not in the same plane.  This
is not easily measured other than by sighting or on a plane table.
The trouble with forks is that they are more difficult to measure even
though shops will not admit it.  It takes good fixturing to align a
fork because a short fork blade can escape detection by most
measurement methods.  Meanwhile lateral and in-line corrections may
seem to produce a straight fork that still pulls to one side.
However, the crude guy who uses the method I outlined above will make
the bike ride straight without measurement.  The only problem with
this is that the bike may pull to one side when braking because the
fork really isn't straight but is compensated for lateral balance.

This problem has mystified more bike shops because they did not recognize
the problem.  Sequentially brazing or welding fork blades often causes
unequal length blades and bike shops usually don't question this dimension.
However, in your case I assume the bike once rode straight so something
is crooked

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

Frame repair  (David Keppel  [e-mail])

(Disclaimer: my opinions do creep in from time to time!)

When frames fail due to manufacturing defects they are usually
replaced under warranty.  When they fail due to accident or abuse
(gee, I don't know *why* it broke when I rode off that last
motorcycle jump, it's never broken when I rode it off it before!)
you are left with a crippled or unridable bike.

There are various kinds of frame damage that can be repaired.  The
major issues are (a) figuring out whether it's repairable (b) who
can do it and (c) whether it's worth doing (sometimes repairs just
aren't worth it).

Kinds of repairs: Bent or cracked frame tubes, failed joints, bent
or missing braze-on brackets, bent derailleur hangars, bent or
broken brake mounts, bent forks, etc.  A frame can also be bent out
of alignment without any visible damage; try sighting from the back
wheel to the front, and if the front wheel hits the ground to one
side of the back wheel's plane (when the front wheel is pointing
straight ahead), then the frame is probably out of alignment.


* Can it be repaired?

Just about any damage to a steel frame can be repaired.  Almost any
damage to an aluminum or carbon fiber frame is impossible to repair.
Titanium frames can be repaired but only by the gods.  Some frames
are composites of steel and other materials (e.g., the Raleigh
Technium).  Sometimes damage to steel parts cannot be repaired
because repairs would affect the non-steel parts.

Owners of non-steel frames can take heart: non-steel frames can
resist some kinds of damage more effectively than steel frames, and
may thus be less likely to be damaged.  Some frames come with e.g.,
replacable derailleur hangers (whether you can *get* a replacement
is a different issue, though).  Also, many non-steel frames have
steel forks and any part of a steel fork can be repaired.

Note: For metal frames, minor dents away from joints can generally
be ignored.  Deep gouges, nicks, and cuts in any frame may lead to
eventual failure.  With steel, the failure is generally gradual.
With aluminum the failure is sometimes sudden.

Summary: if it is steel, yes it can be repaired.  If it isn't steel,
no, it can't be repaired.


* Who can do it?

Bent derailleur hangers can be straightened.  Indexed shifting
systems are far more sensitive to alignment than non-indexed.  Clamp
an adjustable wrench over the bent hanger and yield the hanger
gently.  Leave the wheel bolted in place so that the derailleur hanger
is bent and not the back of the dropout.  Go slowly and try not to
overshoot.  The goal is to have the face of the hanger in-plane with
the bike's plane of symmetry.

Just about any other repair requires the help of a shop that builds
frames since few other shops invest in frame tools.  If you can find
a shop that's been around for a while, though, they may also have
some frame tools.


* Is it worth it?

The price of the repair should be balanced with

 * The value of the bicycle
 * What happens if you don't do anything about the damage
 * What would a new bike cost
 * What would a new frame cost
 * What would a used bike cost
 * What would a used frame cost
 * What is the personal attachment

If you are sentimentally attached to a frame, then almost any repair
is worth it.  If you are not particularly attached to the frame,
then you should evaluate the condition of the components on the rest
of the bicycle.  It may be cheaper to purchase a new or used frame
or even purchase a whole used bike and select the best components
from each.  For example, my most recent reconstruction looked like:

 * Bike's estimated value: $300
 * Do nothing about damage: unridable
 * Cost of new bike: $400
 * Cost of new frame: $250+
 * Cost of used bike: $200+
 * Cost of used frame: N/A
 * Cost of repair: $100+
 * Personal attachment: zip

Getting the bike on the road again was not a big deal: I have lots
of other bikes, but I *wanted* to have a commuter bike.  Since I
didn't *need* it, though, I could afford to wait a long time for
repairs.  The cost of a new bike was more than I cared to spend.
It is hard to get a replacement frame for a low-cost bicycle.  I
did a good bit of shopping around and the lowest-cost new frame
that I could find was $250, save a low-quality frame in the
bargain basement that I didn't want.  Used frames were basically the
same story: people generally only sell frames when they are
high-quality frames.  Because the bike was a road bike, I could have
purchased a used bike fairly cheaply; had the bike been a fat-tire
bike, it would have been difficult to find a replacement.  The cost
of the frame repair included only a quick ``rattlecan'' spray, so
the result was aesthetically unappealing and also more fragile.  For
a commuter bike, though, aesthetics are secondary, so I went with
repair.

There is also a risk that the `fixed' frame will be damaged.  I had
a frame crack when it was straightened.  I could have had the tube
replaced, but at much greater expense.  The shop had made a point
that the frame was damaged enough that it might crack during repair
and charged me 1/2.  I was able to have the crack repaired and I
still ride the bike, but could have been left both out the money
and without a ridable frame.


* Summary

Damaged steel frames can always be repaired, but if the damage is
severe, be sure to check your other options.  If the bicycle isn't
steel, then it probably can't be repaired.

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

Frame Fatigue  (John Unger  [e-mail])

I think that some of the confusion (and heat...) on this subject
arises because people misunderstand the term fatigue and equate it
with some sort of "work hardening" phenomena.

By definition, metal fatigue and subsequent fatique failure are
well-studied phenomena that occur when metal (steel, aluminum,
etc.) is subjected to repeated stresses within the _elastic_ range
of its deformation. Elastic deformation is defined as deformation
that results in no permanent change in shape after the stess is
removed. Example: your forks "flexing" as the bike rolls over a
cobblestone street.

    (an aside... The big difference between steel and aluminum
    as a material for bicycles or anything similar is that you
    can design the tubes in a steel frame so that they will
    NEVER fail in fatigue. On the other hand, no matter how
    over-designed an aluminum frame is, it always has some
    threshold in fatigue cycles beyond which it will fail.)

This constant flexing of a steel frame that occurs within the
elastic range of deformation must not be confused with the
permanent deformation that happens when the steel is stressed beyond
its elastic limit, (e. g., a bent fork). Repeated permanent
deformation to steel or to any other metal changes its strength
characteristics markedly (try the old "bend a paper clip back and
forth until it breaks" trick).

Because non-destructive bicycle riding almost always limits the
stresses on a frame to the elastic range of deformation, you don't
have to worry about a steel frame "wearing out" over time.

I'm sorry if all of this is old stuff to the majority of this
newsgroup's readers; I just joined a few months ago.

I can understand why Jobst might be weary about discussing this
subject; I can remember talking about it on rides with him 20 years
ago....

---------------------------------------------------------------------------
Weight = Speed?  (Jobst Brandt  [e-mail])

> I was wondering if anyone could help me figure out why heavier
> people roll down hills faster than the little scrawnies like myself.

Surface as well as cross sectional area of an object (a human body)
increases more slowly than its weight (volume).  Therefore, wind drag,
that is largely dependent on surface, is proportionally smaller for a
heavier and larger object than a smaller one of similar shape and
composition.  A good example is dust at a rock quarry that remains
suspended in the air for a long time while the larger pieces such as
sand, gravel, and rock fall increasingly faster to the ground.  They
are all the same material and have similar irregular shapes but have
different weight to surface area ratios, and therefore, different wind
resistance to weight ratios.  This applies equally to bicyclists
coasting down hills if other factors such as clothing and position on
the bicycle are similar.

---------------------------------------------------------------------------
Aligning SPD Cleats  (Bill Bushnell  [e-mail])

Six adjustments can be made when setting up SPD cleats.  With the foot
parallel to the ground and pointing in the direction of travel, the
adjustments are:

1) Left/right translation
2) Front/back translation
3) Up/down translation
4) Front to back tilt
5) Side to side tilt
6) Azimuth, often called "rotation"

Front to back tilt is adjusted as the bicycle is pedaled since the
pedals themselves rotate freely in this direction.

Some people may need to adjust side to side tilt, but this requires
the use of shims which are not provided and can cause the cleat to
protrude beyond the tread of the shoe.  Custom insoles that have
one side slightly thicker than the other may have the same effect
as shims between the cleat and the shoe.

Separate up/down adjustments for each leg may be necessary for
individuals with established leg length differences.  To adjust
up/down translation in one shoe use a combination of an insole
and raise or lower the seat.  To make small up/down changes
equally in both legs, simply raise or lower the seat.

The usual adjustments for SPD cleats are left/right, front/back,
and Azimuth.  Of these Azimuth is the most sensitive.  For most
people these three adjustments are sufficient to obtain a
comfortable alignment.

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

Aligning SPD cleats:

Position the cleat so that it lies on the imaginary line between the
bony knob on the inside of your foot at the base of your big toe and
a similar but smaller knob on the outside of the foot at the base of
the smallest toe.  Set azimuth so that the pointed end of the cleat
points directly toward the front of the shoe.

If you're switching from clips and straps, and you are satisfied with
your current alignment, use the following alternate method.  Position
your SPD shoe fully in the clip of your old pedal and align the cleat
to the spindle of your old pedal.  Center the cleat in the X direction,
leaving room to adjust either way should the need arise.

Some people find pedaling more comfortable if their left and right
feet are closer together.  This is sometimes called the "Q-factor".
If you prefer to start with a low Q-factor, then move the cleat so that
it is as close as possible to the outside of the shoe.  Tighten both
cleat bolts before engaging the pedal.

Adjust the release tension of the pedals so that it is somewhere in
the low to middle part of the tension adjustment range.  The higher
the release tension, the harder it will be for you to disengage the
pedals when dismounting.  The lower the release tension, the easier it
will be for you to inadvertently pull out of the pedals, especially
when standing and pedaling.  If you stand often to power up hills,
consider setting the initial release tension higher as an unwanted
release under these conditions can result in a painful spill.  See
the pedal instructions.

Mount your bike on a trainer, if you have one, to make preliminary
cleat and release tension adjustments.  Practice engaging and
disengaging the pedals a few times before you take a real ride.
Soon you will find this easy.  If you notice that a shoe rubs a
crank or chainstay, adjust left/right translation and azimuth
until the shoe no longer rubs.

As you pedal, you will probably find the initial azimuth
uncomfortable on one or both legs.  Notice how your foot would like
to rotate.  Adjust the azimuth of the appropriate cleat in the same
direction your foot wants to rotate.  For example, if your foot
wants to rotate clockwise, adjust the azimuth of the cleat (when
looking at the bottom of the shoe) clockwise.  Start by making
moderate corrections.  If you overshoot the adjustment, correct by
half as much.

As you approach optimum azimuth, you may need to ride longer before
you notice discomfort.  Take your bike off the trainer, and go for
a real ride!  And bring your 4mm allen key.

You may find very small azimuth adjustments difficult to make.  This
happens because the cleat has made an indentation in the stiff sole
material (usually plastic, sometimes with a tacky, glue-like
material where a portion of the sole was removed).  When you tighten
the cleat after making a small correction, it will tend to slide back
into the old indentation.  Try moving the cleat one millimeter or so
to the side or to the front or back, so the cleat can no longer slip
into the old indentation pattern as it is being tightened.

Pain in the ball of your foot can be relieved.  One way is by moving
the cleat rearward.  Start by moving the cleat about two to three
millimeters closer to the rear of the shoe.  Be careful not to change
the azimuth.  When pedaling notice how far your heel is from the
crank.  After making a front/rear adjustment, check to make sure the
crank-heel distance has not noticeably changed.

Moving a cleat rearward on the shoe has the effect of raising your seat
by a lesser amount for that leg.  The exact expression is messy, but
for an upright bike, the effect is similar to raising your seat by
about y/3 for that leg, where y is the distance you moved the cleat to
the rear.  For example, if you move your cleat 6 millimeters to the
rear, you might also want to lower your seat by about 2 millimeters.
Remember, though, that unless both cleats are moved rearward the same
amount, your other leg may feel that the seat is too low.

Another way to relieve pain in the ball of the foot is to use a custom
orthotic and/or a padded insole.  Most cycling shoes provide poor arch
support and even poorer padding.

After riding for a while with your aligned cleats if you find yourself
pulling out of the pedals while pedaling, you will need to tighten the
release tension.  After tightening the release tension the centering
force of the pedals will be higher, and you may discover that the
azimuth isn't optimum.  Adjust the azimuth as described above.

On the other hand, if you find you never pull out of the pedals while
pedaling and if you find it difficult or uncomfortable to disengage
the cleat, try loosening the release tension.  People whose knees
like some rotational slop in the cleat may be comfortable with very
loose cleat retension.

As with any modification that affects your fit on the bike, get used
to your pedals gradually.  Don't ride a century the day after you
install SPDs.  Give your body about two or three weeks of gradually
longer rides to adapt to the new feel and alignment, especially if
you've never ridden with clipless pedals before.  Several months after
installing SPDs, I occasionally tinker with the alignment.

After performing the above adjustments if you are still uncomfortable,
seek additional help.  Some people can be helped by a FitKit.  If
you're lucky enough to have a good bike shop nearby, seek their
advice.

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

Tightening cleat bolts:

Tighten cleat bolts until they _begin_ to bind.  This will happen when
further tightening produces a vibration or squeal from the cleat.
Tighten no further or you may damage the mounting plate on the inside
of the shoe.   After living for a while with a comfortable alignment,
remove each mounting bolt separately, apply blue loctite on the
threads, and reinstall.  Should you later find you need to loosen a
bolt to adjust the alignment, you will have to reapply the loctite.

Keeping the Pedal/Cleat interface clean:

Occasionally you may find the pedals suddenly more difficult to
disengage.  This usually happens because dirt or other contaminants
get caught in the cleat or pedal mechanism.  I have found that a good
spray with a hose quickly and cleanly washes off dust, mud, or other
gunk from the pedal and cleat.  You may also wish to spray the pedal
with a light silicone or teflon lubricant.

Acknowledgements:

John Unruh ([e-mail])
Lawrence You ([e-mail])