Advice on Buying a Bike

This document is copyright 1995 by Tom Holub. It may be freely redistributed as long as this notice is retained.
It may not be sold.

This seems like as good a time as any to discuss purchasing and sizing a bicycle. If you already have a bike and aren”t interested in getting
another one, you can skip down to the Sizing section. Having more than one bike is way cool, though, especially if your bike is your only form of transportation.

I”ll start by saying that low-end bike-store bikes have gotten
a lot better over the last 10 years; you can”t really go wrong. As a
general rule, it”s worth spending extra money up to about $700 or $800;
after that you”re paying for stuff you don”t really need. If the
guy at the bike store is telling you about some cool feature the bike
has (like underbar push-button shifters) you are probably paying for
stuff you don”t need. Bike Hint says: The features you need on your bike
are pedals that go around, brakes that work and shifters that work;
everything else is vestigal. That”s not to say that you should buy the
cheapest functional bike; you should just be aware that extras aren”t
really necessary.

Note that I said low-end *bike-store* bikes. Do not buy bikes from
Target, Toys R Us, or any other non-bike store. Those bikes are cheap
in dangerous ways; the brakes are particularly bad. They”re heavy,
they”re constructed by morons, and they are practically impossible
to adjust properly. Do yourself a favor, buy a reasonable bike.
Expect to spend $250; in this case, you get more than what you pay
for.

I should get some terms defined here. Your frame has 4 tubes:

TOP TUBE: The, uh, top tube. The rear brake cable usually runs along it.

SEAT TUBE: The tube which holds the SEAT POST.

DOWN TUBE: The other main tube, the diagonal one on the bottom. It has
shifters on some road bikes, usually has water-bottle brazes, and
the shifter cables usually run along it.

HEAD TUBE: *Not* a cheesy porn flick. This is the short tube which
connects the down tube to the top tube. Inside it are the STEERER
TUBE and the STEM.

STEERER TUBE: The tube connected to the FORK (which holds the front wheel)
and the STEM through the HEAD TUBE.

STEM: Controls the STEERER TUBE and holds the handlebars. It is adjusted
via an allen bolt (usually) on the top.

SEAT POST: Holds the seat. It is adjusted by a bolt at the top of the
SEAT TUBE. It holds the seat in a clamp; the seat is adjusted via
a bolt on this clamp.

I look for the following minimal features in a bike:

ALUMINUM WHEELS: Not only are they lighter than steel, they”re easier to
keep in adjustment, and they are *much* better at braking when wet.
They say that upgrading your wheels is the easiest way to upgrade the
performance of your bike; start off with good ones.

NO IDIOT LEVERS: If your bike is a road bike with the curved “drop”
handlebars, the brakes are mounted on the “hooks.” On cheap bikes,
in addition to the main brake lever, there is another lever that
extends inwards, parallel to the bars. Do not buy a bike with these;
they are extremely dangerous (they don”t brake well enough to use in an
emergency) and they”re a sign that the bike is not designed well.
If your bike has these levers, I suggest removing them. Really.

NO STEM SHIFTERS: Again, this is for road bikes; on some bikes, the
shifters are mounted on the stem (the thing that holds the handlebars).
The idea is that they”re closer to your hands and therefore easier
to use; the reality is that you have to raise your center of gravity
while twisting your body to use them. They also are very susceptible
to being hit by your knees while climbing (a very bad scene), and
in an accident they can wind up goring your throat. Insist on
down-tube or bar-end shifters for road bikes.

As you probably know, there are three main types of bikes:

ROAD BIKES: Dropped handlebars, thin tires, downtube shifters. Road bikes
are lightweight and fast and have significant advantages over the
other types for road riding. They can also ride on packed dirt roads
without much trouble; they can”t ride in loose dirt or sand. One
drawback road bikes have in Berkeley is that, because of their narrow
tires, they don”t handle bumps and potholes as well as the other types.
One advantage they have is that thieves don”t seem to be interested in
them.

Touring bikes, such as the Bridgestone RB-T, are road bikes with
wider tires and a more relaxed geometry to handle bumps better. I find
them to be excellent for commuting; my main commuting bike is a
Schwinn Voyageur (sadly, Schwinn no longer makes it). They are slower
than other road bikes but faster than the other types.

One problem you”ll have buying a road bike is that most bike stores
don”t carry inexpensive ones, so you”ll find it difficult to get a
test ride on anything cheaper than $500. Since I highly recommend
a test ride, this is a significant drawback.

MOUNTAIN BIKES: Straight handlebars, big knobby tires, handlebar shifters.
Mountain bikes own the lion”s share of the new bike market; they”re
fun to ride and cool to look at (people who want to look at their bikes
rather than ride them tend to buy mountain bikes). They are great at
handling bumps and can also ride in loose dirt or on singletrack trails.
They are significantly slower than road bikes on roads; just yesterday
I was riding my mountain bike and felt like I had no energy at all.
They also are targets for theives in Berkeley; if you own a mountain
bike, be prepared to take extra precautions to protect it.

Mountain bikes are viewed as being more comfortable because your riding
position is more upright; this is incorrect. This position is more
comfortable only while you”re looking at the bike, or perhaps sitting
on it in the bike store. It puts more strain on your lower back, and
the lack of extra hand positions also causes problems on long rides.

Mostly because of the theft issue, I can”t in good faith recommend a
mountain bike for commuting in Berkeley. If you”re looking for a bike
you can take anywhere, or if you specifically want to ride off-road,
mountain bikes are great, but I think taking them to campus every day
is a bad idea unless you have a private office where you can keep them.

HYBRIDS: After the mountain bike boom of the early 80”s, people started
realizing that they weren”t riding their mountain bikes off-road.
Since mountain bikes have significant disadvantages on-road, hyrbids
were created to combine the features of mountain bikes and road bikes.
They usually have an upright riding position but less so than mountain
bikes. Their tires are wider than road bikes” but usually not too
knobby. They often have handlebars with more hand positions than
mountain bikes do.

As you might expect, they are faster than mountain bikes but slower
than road bikes. They are theft targets more than road bikes but
less than mountain bikes. They are better in loose dirt than road
bikes but aren”t really appropriate for serious off-road riding.
I find that hybrids make decent commuting bikes, but the upright
riding position makes them undesirable for long rides. For around-town
riding they”re good though. There tend to be a lot of hybrid selections
under $500 since they”re aimed at casual users; the Bridgestones (if
you can still get them) are nice bikes.

There are also recumbents (bikes on which you sit on what looks like a
deck chair) and tandems. Recumbents are comfortable and attract a lot
of attention; they are bad at climbing hills but good at flats and
downhills. There”s a growing recumbent market. Tandems (two-man bicycles)
are the most fun you can have on two wheels, but good ones are expensive.

HOW TO CHOOSE A BIKE

First, obviously, you need to decide how much money you are prepared to
spend. I advise being generous; as I said earlier, spending extra money
will get you a better bike. Expect to spend at least $250; you won”t
get many choices at that level so realistically you should expect to spend
$300. If you can”t afford to spend that much, you can get good deals
on good used bikes if you look around; lots of people never ride their
bikes and eventually wind up just dumping them. A used quality bike
will serve you much better than a new Target junker.

Once you have a price range, head to a bike store. I personally like
Missing Link, but any bike store with a lot of bikes in stock is fine
(except Hank & Frank, they suck rocks). Do not allow yourself to be
rushed; test-ride a number of bikes and don”t skimp on the rides (details
on test riding below). Consider theft resistance; does the bike have
a quick-release seat that you”ll need to buy a cable for, or take with
you? Look at the frame joints; are the welds (or brazes) clean or
sloppy? Are the wheels true? The brake lever end should have a maximum
travel of about 2 inches (a little less for mountain bikes) and you should
not be able to bottom it out. Are the brakes sidepull or cantilever?
(Cantilever brakes are mounted on pivots on the fork and seatstays, with
the main cable pulling a transverse cable which straddles the wheel.
Sidepulls are mounted directly above the wheel with the cable pulling
them together on one side.) Cantilever brakes are good if you plan to
put fenders on the bike (which immensely improves cycling in the rain).
Sidepull brakes tend to work more smoothly and stay in adjustment better.

HOW TO TEST RIDE A BIKE

The main things you”re interested in on a test ride are to find out how
the bike handles bumps, to find out how the brakes and shifters work,
and to see if it was well-built. Before you go to the bike shop you
should have a plan for where you intend to take the bikes you test.
Take the bike on Hearst or somewhere similar; how much does it jar you when
you”re going downhill? When it hits bumps, do you hear unexplained rattles?
You should expect your rear derailleur to snap when you hit bumps, but if
other things on the bike are rattling it”s a sign that something is
cheap or poorly fitting.

To test the shifters, start by riding on a flat road and shifting through
all the gears. Does it easily shift into the lowest gear? If you
overshift into the lowest gear, does the derailleur sound like it wants
to self-destruct into the spokes? (if it does, stop overshifting, but
that”s a count against the bike.) Does it shift cleanly into the
highest gear, without jumping over the end? Can you shift between the
front chainrings easily, without the chain jumping off? On a triple
crankset it can be expected that the chain will jump off sometimes
when shifting to the smallest chainring, but on a double it should never
hop off and it should never hop off when shifting to the large chainring.
Try out each cog for a while; does the chain run smoothly and quietly
on each cog, or does it chatter or jump off one or more?

Try to downshift while pedaling uphill; it”s harder to shift with tension on
the chain and cheaper shifting systems will fail to. If you”re spending
$500 or more, though, you should insist that the bike be able to make this
shift cleanly.

When you”re riding uphill, do you hear pinging sounds in the wheels?
If you do, they were poorly built; the sounds will eventually go away
but the wheel will need to be retrued.

Head downhill and hit the brakes; do you stop smoothly? Do you feel like
you have control over your deceleration? Cantilever brakes are somewhat
rougher than sidepulls and feel spongier, so expect that.

Walk the bike while turning the handlebars; do they turn smoothly through
their range of motion, or does it feel like there are notches at various
points (especially straight ahead)? Try some medium-speed turns on
pavement; does the bike corner solidly (if a road bike; knobby-tire bikes
corner horribly on pavement)?

If you are planning on riding off-road, find a dirt trail or two (there
are some on campus) and see how the bike handles them; can you accelerate
from low speed on the dirt? Can you turn without skidding? Can you shift
on a bumpy section?

As I said, try out a number of different bikes in your price range; there”s
no way to measure how good a bike feels to you. And most importantly,
once you buy it, RIDE BIKE!

SIZING A BIKE

There is no formula to determine perfect bike size and adjustment; there
are plenty of rules of thumb, but really bike adjustments are a highly
personal thing. You are the only one who can determine your perfect setup.

That said, here are some rules of thumb: Your seat height should be adjusted
so that your leg is almost fully extended at the bottom of your pedal stroke.
Test this by sitting on the bike leaning against a wall. Put your heels
on the pedals and pedal backwards; your leg should be fully extended at the
bottom. Most people adjust their seats too low; I”ve seen “cycle safety”
manuals that recommend keeping your seat low enough that you can put
both feet on the ground while sitting on your seat (HINT: Do not do this).
Low seat height is the major cause of cycling knee injuries.

You can adjust the tilt of the seat by loosening the bolt on the clamp
underneath it. Most people are comfortable when their seat is level, or
tilted just slightly forward, but again, this is mostly a matter of
personal preference. I”ve ridden comfortably with a seat tilted back.

Stem height is another preference thing; most people are comfortable when
the height of the stem is about the same as the height of the seat; higher
will give a more upright riding position, lower will bend you over more.
Mountain bikes usually have stems that place the handlebars a little
higher than the seat to promote the upright riding position.

Stem extension is a measure of how far in front of the head tube the
stem holds the handlebars. It cannot be adjusted without buying a new
stem, but you might be able to get a good bike shop to swap stems on a
new bike. If it feels like the handlebars are too far away, a stem
with a shorter extension (ahem) might be good for you. If you have a
long torso, a longer extension could help.

If you have dropped handlebars, the tilt of the bars can also be adjusted;
usually the bolt is under the stem where it clamps the handlebars. As
a general rule, the end of the bars should be aiming at a point somewhere
between the top and the center of the rear wheel, but again, that”s
a preference thing. Some people do whacky things with the bars, pointing
the ends straight up in the air or having them upside down. I recommend
against that; it invites impalement. Also, ALWAYS keep something stuffed
in the end of your bars, whether it”s the plug that game with the
handlebar tape, a fancy expander plug, or a champagne cork.

That”s about it for the adjustments. Always remember that your gut
feelings are more important than the rules of thumb; if you are more
comfortable, especially on long rides, with some non-standard setup,
by all means use it. And Ride Bike!

Gearing

This document is copyright © 1995 by Tom Holub. It may be freely
redistributed as long as this notice is retained. It may not be sold.

In the last installment I discussed the role of maintaining proper
cadence in improving cycling enjoyment and endurance (if you missed it,
it”s in Cadence). The purpose of a bicycle gearing
system, as with an automobile gearing system, is to keep the engine
operating within a certain range of RPM (for a car, 2000-5000ish; for a
bike, 80-100). Because the RPM range on a bike is much more restricted,
bicycles need finer gradations between gears, and because of other
engineering considerations, bike gearing is harder to use than car
gearing. For this reason and others, many cyclists never learn how to
use their gearing system (even those cyclists who buy mountain bikes
because they have “21 speeds”). But really it”s not that hard, and
since bike components have improved markedly in the past 15 years,
shifting is easier now than ever, especially on inexpensive bikes
(unless they have Shimano under-bar shifters, but that”s another rant).

First, we need to get some terms out of the way, then I”ll add a bit on
how gearing works from a rider”s view, and then a more technical
discussion of what goes into a gearing system and how to set up your own
(non-geeks can skip the last part).

DEFINITIONS:

The chain runs on the CHAINRINGS in front and the FREEWHEEL in back (the
FREEWHEEL is so called because it floats freely on the hub, allowing you
to coast or pedal backwards; early bikes couldn”t do either). The
freewheel is made up of five to eight COGS (most modern bikes have
seven, though 8 is becoming more popular. I”m going to assume 7 for
this document). The FRONT DERAILLEUR moves the chain between chainrings
by pushing on the tense (top) part of the chain. The REAR DERAILLEUR
takes up (or lets out) slack in the chain, and moves the chain between
freewheel cogs by moving the slack (bottom) part of the chain
underneath the desired cog. The SHIFTERS are levers that move the
derailleurs by pulling on the DERAILLEUR CABLES. The notation for the
current gear involves a character denoting the chainring and a number
denoting the cog. The small chainring is usually denoted L, the large
usually H, the middle, if it exists, M. The largest cog is denoted 1,
so L1 is the smallest chainring, largest cog.

OK, now down to basics. What your gearing system does is change the
ratio between your pedal revolutions and wheel revolutions. “Low” gears
have a small number of wheel revolutions per pedal revolution (the
lowest gears on bikes with 3 chainrings can go below 1:1 ratios). High
gears have more wheel revolutions per pedal revolution; the highest
gears get up to about 4 wheel revolutions per pedal revolution. The
gearing system is able to change this ratio by changing the effective
size of the wheel and the cranks (by moving to larger or smaller cogs or
chainrings). Smaller chainrings make for lower gears because they
reduce the length of chain that is pulled around in a pedal revolution.
Larger cogs make for lower gears because they require more chain to be
pulled to turn them. So you are in your lowest gear when the chain is
on the smallest chainring and the largest cog (inverse for the highest
gear). In the notation discussed above, this is “L1.”

Many people believe (incorrectly) that their bike has two sets of gears:
“low” ones when the chain is on the small chainring, and “high” ones
when the chain is on the large chainring. In fact there is considerable
overlap between the two, and each bike has a calculable ideal shifting
pattern that requires at least one crossover between chainrings (many
shifting patterns require more). For details on calculating the
shifting pattern of your bike, see below.

However, it”s not really necessary to calculate and remember your
shifting pattern to get more out of your gearing system. Just remember
three things: One, you need to cross over to the large chainring
somewhere in the middle of your freewheel; that is, if you climb a hill
in your lowest gear (L1) and want to shift up after the hill ends, you
can shift to L2, then L3, then maybe L4, but before you get too far you
want to get onto the large chainring by shifting to H2 or possibly H3
(that”s a double-shift to a larger chainring, larger cog). You can
actually get by shifting directly across (L3 to H3) but should be
careful not to let your cadence drop too much.

Two, if you have a triple chainring, your smallest chainring is probably
what is called a “granny”; very low gears for big hills. With a granny
you use only the biggest 2 or 3 cogs (L1, L2, L3); if you need a higher
gear you should get back on the middle chainring. L1 and L2 are usually
far lower than M1, L3 is usually pretty close to M1. If you go much
above the third cog on the smallest chainring, you will probably throw
your chain.

Three, NEVER use the largest chainring, largest cog, or smallest
chainring, smallest cog combinations (H1 or L7), for two reasons.
First, the steep angle the chain has to take causes excessive wear on
the chain, the cogs, and the chainrings. But more importantly, these
combinations tax the ability of the rear derailleur to deal with the
slack in the chain. The H1 combination can immediately jam the chain if
the chain is a link too short, and the L7 combination usually puts more
slack into the chain than the derailleur is able to take up; when the
chain is too slack, any jolt or bump can knock it off the cogs. Thrown
chains (along with flat tires) are the most common cycling problem,
mostly because people insist on riding in the L7 gear. It”s somewhat
natural, because in this position both the derailleurs are “relaxed” (no
tension on the cable) and the shifters are usually both in the same
position. But it”s a bad idea and in any case it”s usually a redundant
gear that H5 or H6 can replace easily.

That”s about all you really *need* to know to shift effectively. For
the whole story, read on.

The original bicycles were known as “high-wheelers” or
“penny-farthings,” the former because the front wheel was huge, the
latter because the difference in size between the front and rear wheels
was similar to the difference in size between a penny and a farthing.
The cyclist sat high up on the front wheel and turned cranks mounted on
the axle. As you might imagine, these bikes were highly dangerous; when
the chain-drive bike was invented (fortunately, not too long after the
penny-farthing) it was known as the “safety bicycle.”

The front wheel was huge because a larger wheel travels further with
each pedal revolution. By changing wheels, cyclists could shift to a
lower or higher “gear.” It was a cumbersome system, but one thing from
it remains to this day; gears on “safety bicycles” are measured in
“gear-inches.” A gear of 50 gear-inches (usually written as a “50-inch
gear”) has the same gear ratio (wheel turns:pedal turns) as a
high-wheeler with a front wheel 50 inches in diameter. The safety
bicycle gives another advantage over the penny-farthing here; the
maximum gear on a penny-farthing is limited by the length of the
cyclist”s legs (since he has to reach the pedals in the middle of the
wheel). Top gear on most road bikes is usually 100+ inches.

You can figure out your ideal shifting pattern by computing the
gear-inches of each of your gear combinations and putting them in a
little chart (see below). Beware that gear-inches are on a logarithmic,
not linear, scale. The formula for gear-inches is:

number of teeth on chainring
—————————- * diameter of wheel in inches.
number of teeth on cog

(or * )

When you think about it, this makes sense. When the number of teeth on
the chainring is equal to the number of teeth on the cog, one revolution
of the pedals produces one revolution of the wheel; therefore one
revolution of the pedals produces the same wheel motion as one
revolution of pedals attached directly to the wheel would. The biggest
problem is counting the teeth; some chainrings and cogs have the number
of teeth etched into the side, but most you have to count by hand. An
experienced eye can make good guesses, though.

For posterity”s sake, here are the gearings on my bikes. There”s a cool
Hypercard stack, ~tom/bikestuff/Bike_Gear.sea.hqx, that will do the
calculations for you and print out a cool graph on a logarithmic scale,
but to just generate the numbers is a fairly simple C/perl program if
someone wants to do it.

First, my Traveler, the bike I usually take on CSUA rides. It”s set up
for road riding without much extra weight; it has 2 chainrings and 7
freewheel cogs.

L H
_____________
| 44 | 54 | 1 The optimal shifting pattern is something like
|—–|—–| L1-L2-L3-L4-L5-H4-H5-H6-H7. The L5-H4 shift is a pain,
| 49 | 61 | 2 so usually I will do L4-H4 or L5-H5. This is known as
|—–|—–| Alpine gearing because it gives lots of high and lots
| 57 | 70 | 3 of low gears for big hills. 44 gear-inches is not a
|—–|—–| particularly low gear but it usually suits my purposes
| 67 | 83 | 4 for this bike. 117 inches is quite a big gear,
|—–|—–| bigger than I really need, but it”s great for Bear
| 76 | 94 | 5 Creek Road and other big descents. This is my
|—–|—–| recreational bike, after all.
| 87 | 108 | 6 Note that L7 and H1 are virtually duplicated.
|—–|—–|
| 94 | 117 | 7
————-

This one is for my Voyageur, the bike I use for touring and usually
commuting (as well as riding in the rain). It has a good rack, fenders,
sizable tires, and other features that make it good for riding with
weight. It has a triple chainring and 7 freewheel cogs.

L M H
___________________
| 31 | 49 | 59 | 1 This setup I made myself; the idea is that the
|—–|—–|—–| L ring takes care of all the really low gears,
| 34 | 54 | 65 | 2 so it”s possible to have a very narry spacing on
|—–|—–|—–| the other two chainrings (I don”t really need
| 38 | 60 | 73 | 3 super-high gears when touring or commuting, as
|—–|—–|—–| opposed to recreational riding). The shift
| 43 | 68 | 83 | 4 pattern is something like L1-L2-L3-M1-M2-M3-M4-
|—–|—–|—–| M5-M6-H4-H5-H6-H7. Again, the M6-H4 shift is
| 46 | 73 | 89 | 5 a pain and usually becomes M5-H5 or something.
|—–|—–|—–| Because of this I think this system is suboptimal
| 50 | 79 | 96 | 6 but for my uses it is adequate. Note that
|—–|—–|—–| while this bike has more “speeds” it actually
| 54 | 86 | 104 | 7 has a lower top end.
——————-

This last one is for my MB-3. It”s a mountain bike, obviously, with
a triple chainring and 7 freewheel cogs. It has a rack but rarely
carries much weight.

L M H
___________________
| 21 | 33 | 40 | 1 Mountain bikes need very low gears to get up
|—–|—–|—–| short, steep sections of trail with poor traction.
| 24 | 38 | 46 | 2 The granny ring combined with a fairly large
|—–|—–|—–| rear cluster provides a lower than 1:1 ratio
| 27 | 43 | 52 | 3 when needed (mountain bike wheels are about 26
|—–|—–|—–| inches in diameter). The rest of the pattern
| 31 | 49 | 60 | 4 is known as Crossover; so called because you
|—–|—–|—–| can cross over at basically any point. L1-L2-L3-
| 37 | 58 | 70 | 5 M1-M2-M3-M4-H4-H5 etc. or M1-M2-M3-M4-M5-H5 are
|—–|—–|—–| fine patterns, and M3-H3 or M6-H6 also work.
| 42 | 66 | 80 | 6 This flexibility is useful on the trail, since
|—–|—–|—–| you often find yourself needing a higher or
| 48 | 76 | 92 | 7 lower gear quickly and without warning. The
——————- tradeoff is larger average gaps between gears
and a smaller range (note the top end is just 92
inches).

The other major gearing pattern, used on some mountain/touring bikes, is
called Half-Step Plus Granny. It”s for triple chainrings and the
optimal shift pattern is something like L1-L2-L3-M1-M2-H2-M3-H3-M4-H4
etc. Bike magazines tend to honk on mightily about the virtues of
half-step gearing, which is just more evidence that bike magazines
don”t have a clue about how actual cyclists ride. Sure the pattern is
easy to remember but nobody, and I mean NOBODY, does that many double
shifts. If you”re choosing gearing for a bike, look for a setup with no
more than one double-shift. The possible exception would be on bikes
with bar-end shifters (hi kube) since they make double shifts fairly
easy if you often keep your hands near the end of the bars. I had
bar-end shifters and a half-step plus granny system on my Voyageur when
I first got it and hated it. But to each his own.

Anyway, the routes for this Sunday”s ride are in ~tom/bikestuff/routes/
6-26-94. We”re leaving Evans at 11 AM and taking BART to Orinda. If
the weather I had yesterday is any indication, it should be beautiful,
but be sure to bring lots of water because it will be hot. I recommend
freezing your water bottles the night before. The easy ride is shorter
than most but more hilly; the intermediate ride is shorter than most and
maybe a little more hilly (it”s actually a fairly easy intermediate ride),
and the advanced ride is quite hilly but not too long (it”s somewhat
easier than the last advanced ride through Marin).

See you Sunday. Ride Bike!
-Tom