This page was last updated 10 june 2004.

Bicycle Maintenance Guide

(*) (*) (*) (*) (*) (*) (*) (*) (*) (*) (*)
Intro Wheel Steer Drive Comp Wear Ride Travel Accident <<< >>>

Drive Train



Brakes

Brakes are obviously the part of the bicycle that deserves the most attention. There are several different types:

There are a variety of brake pads that vary in softness. If the rubber compound is too hard, it doesn't brake well, especially in wet weather; if it is too soft, it wears down too quickly. Since rubber tends to get harder with time, brake pads should be replaced at least every couple of years. I prefer Campagnolo or Aztec. Some brake pads are longer than others, but I have not found this to make a difference. Some brake pads are designed for steel rims, but they don't make steel rims safe - never use steel rims because they are difficult or impossible to brake in wet weather. Good brake pads are not cheap, but this is about the worst place to save money!

Do not use ``safety levers'' that extend from the brake levers of cheap road bikes towards the stem (that holds the handlebars in the center). They aren't safe because they flex and brake poorly.

In road bike shift levers of the kind used for drop (racing) handlebars, the brake cables connect to the inside of the handle and run along the handlebars under the handlebar tape. The older type where the brake cable connects to the upper tip and arc up and then back down to the brakes are dangerous because you can accidentally catch the cable with your gloves, especially if you have aero (triathlon) bars.

For tips on installing and adjusting brake levers, see the chapter on handlebars.

Gear Shift Levers

Again, there are a number of different types:

On road bikes, the shifter cables run along the down tube, on the left side to the front derailleur and on the right side to the rear derailleur. There is a plastic insert under the bottom bracket that guides the cables. Cables must be bought to match the shifting system used. Ride-on makes special coated cables that run somewhat smoother than regular cables, but don't really justify the price. Normal cables should be oiled with Teflon oil (which doesn't gum up with age) before being inserted into the housing.

Shortening the housing is difficult and requires a special tool, or at least a sharp fine metal saw. The housing should be held by a vise. Saw it off very close to the vise grips, then file the sharp edges and smooth out the inner plastic tube. Use metal caps on the ends. Cables are usually too long; cut them with a sharp cutter and either put a cap on the end or solder the end (but don't use too much solder or they won't fit through the housing caps). Uncapped unsoldered cables fray.

Chainwheels, Cogs, and Chains

In front, there are either two or three chainwheels. The innermost, smallest chainring is intended for spinning up steep hills. It's also called ``granny gear'', presumably to indicate who would need one. Me, I prefer two chainrings on road bikes because I don't have to worry about overshifting, because I have to worry less about extreme chain lines, and because I haven't yet met a mountain that was not easier to climb without a granny gear. The problem with the chainline is that a chain should not run from an inner cog to an outer chainwheel or vice versa.

There are cassettes with eight, nine, or ten cogs on the rear hub (for hub types, see the chapter on wheels). Cassettes with five to seven, and arguable eight, cogs are obsolete. At the time of this writing (2006), nine cogs are still available but fading, and people switch to ten. Ten-cog cassettes require a special narrow chain, and derailleurs and levers may not be compatible, so I recommend going with ten. In most cases, the number of cogs must agree with the type of shift levers; it cannot be upgraded without also replacing the shift lever. Usually cassettes from one vendor cannot be mixed with shift levers from another vendor. There are some exceptions, for example Sachs is said to work with Campagnolo, and Campagnolo sells replacement ratchets to convert levers.

Chains must be the single most neglected part of the typical bicycle. It seems that every other bicycle I see has not been lubricated for years. Unlubricated chains squeak pitifully, make pedaling much harder, and destroy chainwheels and cogs. The problem is that rust and other particles get between the bolts and sleeves of the chain and wear them down, so that the chain gets loose and hence very slightly longer. This means that the distance between two chain links no longer matches the distance between two chainwheel and cog teeth. When this happens only one link connects with a tooth, all others are loose because of the slack. This one tooth takes the entire force and gets worn into a ``shark fin'' shape. If this shape is pronounced enough, the chain won't even roll smoothly off the cog or chainwheel; instead the chain will be grabbed by the shark fin.

The insidious part of this is that you don't notice it until the cogs you use most are already destroyed. Replacing the chain will seem to make matters worse because now all links of the chain get hooked by all the shark fin teeth of the cog simultaneously, which will make the chain skip. This makes the cog unrideable. The only option at this point is to replace all the worn cogs together with the chain.

To prevent this from happening, it is important to lubricate the chain frequently, at least every three weeks or so, more often when riding in wet weather. Before lubricating the chain, it must first be cleaned with an old T-shirt. You can run the chain through the fabric, but it's really better to clean each link individually. It will only take a few minutes. You should also clean the cogs, chainwheels, and especially both pulleys in the rear derailleur. Then, lubricate the inside liberally, and run the chain through at high speed for some time. Then, wipe off all excess lube. This is important because only the lube inside the chain will do any good, the rest just attracts dirt and increases wear. Ride around the block and wipe off excess lube again.

There is much debate about the best chain lube. You can't go wrong with synthetic bicycle chain oil, perhaps containing suspended Teflon or other lubricating particles. Don't use regular (WD-40 or other) machine oil because its viscosity is too low to stay in the chain for very long, and don't use motor oil because motor oil is designed to work in certain (hot) environments only. Grease doesn't work too well because it won't reach the critical parts, you'll wipe off most of what you apply. This is even more true of wax. Don't use gasoline to clean your chain, it will remove the factory grease packing of the inner surfaces and you'll never be able to restore them sufficiently. Chains are not that expensive.

Replacing a Chain

To replace a chain, push a pin out of the old chain and measure the new chain against the old to make sure it has the same number of links. If you have to remove links, remove them at the end without the bolt sticking out. If you have to break a chain with the intent to reinstall it, push one bolt towards the outer side of the bicycle until the link just barely holds together. Bend the chain to disengage the broken link. It's impossible to re-insert a bolt pushed out all the way. To install a chain, join the chain and push the bolt in until it is flush with the link plate, then push it back from the other side until it's as flush with the plate on that side as all the other links. Then, bend the chain sideways until it moves freely. A stiff link makes the chain skip when riding. You need a special chaintool for pushing bolts.

The chain length should be chosen so that all gear combinations are possible: if the chain is on the largest chainring and the largest cog, the rear derailleur should still have some play, and if the chain is on the smallest chainwheel and the smallest cog, it should not touch itself near the upper pulley in the rear derailleur. Of course you won't normally ride these extreme gears because of the poor chainline. If these conditions can't be met, consider changing the pulleys or chainwheels, or the rear derailleur capacity (i.e. use one with a longer cage). As a rule of thumb, the rear derailleur should be roughly vertical (both its pulleys are exactly below the axle) when the chain is on the largest chainwheel and the smallest cog.

In case of doubt I prefer a shorter chain because this increases its tension and makes it less likely to bounce and hit the chainstays (the frame tubes that connect the bottom bracket and the rear dropouts). On mountainbikes ``chain suck'' can become a problem when the chain bounces so much that it gets caught between the chainstay and the chainwheels. You can bolt little gizmos to the chainstay to prevent this, but I have seen these gizmos to cause more chainsuck problems than they solve because if the chain gets stuck anyway it gets stuck so tightly that it requires tools to make the bicycle ridable again. I am generally wary of little add-on gadgets.

Selecting a Gear Range

Bicycle newsgroups are awash with little programs to compute gear ranges, ``gear inches'', and stepping recommendations. I'll take the practical approach.

First, the ratio of front steps to back steps is important. The standard chainring set is 42-52 (teeth). I think of this as 24% step (1-(52-42)/42); if you shift on the big chainring the bicycle goes 24% faster at the same cadence (pedaling speed). The differences for the rear cogs is much smaller. For example, my usual cassette has cogs 13-14-15-16-17-19-21-23. This works out to 8-12% steps, so together with a 39-53 chainwheel set (36%) a front shift is equivalent 3 or more rear shifts. This is unusually large.

If the front-to-rear shift ratio is 1, you have too few distinct gears because for most front shifts there is an equivalent rear shift. A ratio of 0.5 is called ``half-stepping'' because front shifts insert another gear between most rear gears, at the expense of frequent double shifts. A ratio of 1.5 is called ``alpine''; it offers most of the fine gearing of half-stepping but extends the range at the ends, at the expense of even more shifting. My rather extreme ratio of 3 has a different goal; I rarely shift in front and use the small chainring for normal riding and climbing and the big chainring for high-speed downhill or flat-terrain riding.

Modern chainwheels and cogs cannot be combined arbitrarily, they are designed to work together to help the chain move from one cog to the next with small indents and protrusions that ``take over'' the chain and precisely chosen places. I usually pay little notice to this and put my cogs together any way I feel I need for the tour I have in mind, the loss of smoothness is negligible. Effectively, one chooses a rear cog cassette by choosing the extremes, such as 13-23 or 14-32. This decision depends on the type of riding:

Cadence, or pedaling speed, is an important factor here. It is measured in revolutions per minute. Suppose you ride a road bike with a wheel circumference W of 2130 mm at cadence C, using a front chainring with F=42 teeth and a rear cog with R=17 teeth, your speed at C=100 is

    (C * 60) * (F / R) * (W / 1,000,000) = 31.6 km/h

For mph, divide by 1.6. Beginners tend to ride at cadences of 60 or 70 rpm but you should aim at a cadence of around 90 or 100 rpm because it takes less strength and is easier on the knees. High cadences require clipless pedals (a term that means click-in pedals such as Time, Look, or Shimano SPD) because they allow you to apply constant force at all times, rather than stomping the pedal on the downward half of the circle. A bicycle computer that measures cadence is useful to train yourself to use a given cadence, but once you got used to it you won't need the cadence computer any longer.

Pedals

There are basically three types of pedals: pedals with clips and straps, ``clipless'' pedals that a cleat on the shoe clicks into, and pedals with neither.

Clips work best if they are made of plastic and have two prongs that the strap threads through, to prevent them from bending sideways. The strap should be twisted one full revolution inside the pedal to keep it from shifting. The lock at the strap end should be near the outer clip end, such that the other end of the strap points up, where it is easy to grab and tighten when riding. Tightening is unfortunately necessary frequently. It is also often necessary to untighten the strap manually before removing the shoe, especially if the shoe has a cleat with a horizontal groove that fits into the rear pedal edge. This, imho, makes clips dangerous because you may not get out in time in an accident.

Clipless pedals come in a variety of shapes. The two most popular ones are Time and Look, which require a large cleat that makes it hard to walk with the shoe, and Shimano SPD and Ritchey, whose cleats are recessed in the shoe to make it possible to walk normally. There are various clones and other more exotic systems. Racers prefer Time/Look because they hold the shoe more tightly while Shimanos seem to get more float and play (they call it ``freedom'') with every new generation.

Clipless pedals have two advantages that make them useful for anyone except the most casual riders:

Personally, I prefer the Shimano/Ritchey system simply because I have clipless pedals on all my six bicycles and never ride without cleated shoes. Riding to a grocery store and amusing the audience by helplessly staggering about like a penguin because of the cleats is not my idea of convenience. If I raced competitively I would probably feel differently about this. Shimano sells racing cleats that solve much of the excessive sideways play problem.

Shimano pedals can wear out in two ways: the little nose under the front part of the cleat can be worn down, which makes it very hard to disengage from the pedal. This is dangerous but rare. More commonly the front U-shaped back-facing grip of the pedal gets worn from its U shape to a soft curve, which makes the pedal disengage unintentionally. In this case you can either replace the worn part, if you can manage to unscrew it after years of use, or buy new pedals.

Shoes

Shoes must fit the pedals. There are various kinds that accept cleats. They all have a very stiff sole with mounting sockets to attach the cleat to. The shoe should fit well, it should be neither too wide nor too narrow because the feet don't get much exercise while riding and can easily go numb if the shoe doesn't fit. Since good contact with the pedal is essential, they should fit snugly; choose one half size less than you would for a walking shoe.

Adjusting the cleat should be done very carefully because riding with the feet at an unnatural angle hurts the knee. Most people need to adjust the cleat so that the heel points in (of course not enough to touch the crankarms). Most people also prefer to mount the cleats just under the ball of the foot. This takes some experimentation and riding on the block to test adjustments. Don't be careless, knees take a long time to heal...

The soles of the shoes should not be flat but curved up near the toes because they can't bend during walking, being of tough carbon fiber plastic. The attachment point of the cleat must withstand quite enormous force. I have broken five out of six Shimano shoes at that point, three out of four Diadora shoes, and no Adidas shoes. Two of the Shimanos failed catastrophically, I ripped the cleat out of the sole while riding. This is dangerous. One of the Shimanos failed in another nasty way: since the top of the shoe was not very stable, twisting the foot would no longer disengage the pedal! This is even more dangerous. It seems that lately they got better, the newest model has held up for over a year. The Diadoras failed benignly, despite the broken sole they stayed ridable (but of course I replaced them anyway). My Adidases have survived much longer than any of the others and show no signs of failing, but they just recently lowered the quality (by removing padding) and increased the price, so they are no longer attractive. Today I ride cheap Performance shoes - all shoes seem to break after a while regardless of cost so I go with $40 specials.

Derailleurs

Most modern frames have a socket welded to their seat tube that the front derailleur is bolted onto. Most front derailleurs also come in a version that can be strapped to the seat tube if the socket is missing. The derailleur should be adjusted such that the cage is parallel to the chainwheels, and just barely clears the tips of the teeth of the chainwheels as it is shifted back and forth. There are two screws in the body of the derailleur that limit the movement of the derailleur. This prevents overshifting, which would throw the chain off the chainwheels.

Rear derailleurs are available with three different cage lengths (i.e. the distance between the pulleys). The length is called the capacity, and is measured in teeth difference: add the numbers of teeth of the largest chainring and the largest cog and subtract the numbers of teeth of the smallest chainring and the smallest cog. You can exceed the specified capacity of a rear derailleur by a couple of teeth but not more, or the chain will become stuck in unpleasant ways. For standard road bikes, my feeling is that you should stick with the shortest (racing) cage and adjust your chainrings and cogs because longer cages reduce shifting accuracy and make the chain bounce more easily on rough road surfaces. Many high-end rear derailleurs are available only with short cages.

It is absolutely critical to adjust the limit screws of rear derailleurs precisely. If the chain overshifts and falls off the smallest cog, it may block the wheel. If it overshifts at the other end, the derailleur might get caught in the spokes, which will probably crush or snap the derailleur in half and bend the dropout of the frame. A good mechanic may be able to bend the dropout back into shape (this requires special and very expensive frame alignment tools) but this is an excellent way of destroying frames.

Rear derailleurs must match the shift levers, or the gear spacing clicks built into the shift lever won't be translated to the correct cog distances by the derailleur. The result is a rattling noise in some, perhaps most, gears. There is an adjustment screw where the shifter cable enters the derailleur body. Adjust it so you can smoothly shift between the middle two cogs, then test with the whole range. After each adjustment of the screw, shift at least once. I have found it to be impossible to adjust until the chainline looks (and sounds) right and then do the next gear. Always keep shifting during adjustment. This is actually a simple procedure.

Don't bother with special sealed-bearing pulleys. Pulley friction is not a problem, and if the width of the new pulleys doesn't match the width of the original pulleys, the ends of the screws that hold the cage together might either hold the cage together poorly, or worse, stick out and catch the spokes with the usual catastrophic effects. Instead, clean the pulleys regularly, the accumulated gunk makes a much bigger difference. By the way, the back plate of the cage must be installed with the bigger end pointing down, or the chain will keep falling off the lower pulley.

Saddle

Saddles are important because if you choose the wrong one you'll be sore. Make sure it has a narrow nose and a standard-width back. If the nose is too wide it will rub the insides of your thighs. Avoid extra-narrow mountainbike saddles; they allow mountainbike riders to slip their weight easily behind the saddle on steep downhills but the loss of contact area can become painful quickly. There are wider saddles for women, whose pelvis is shaped differently.

Surprisingly, feeling the padding of a saddle for softness does not say much about whether the saddle is comfortable. Saddles usually consist of a hard shell, padded with foam with a flexible plastic cover. The thickness of the foam padding does not make a lot of difference for comfort because there are only two small contact points where bone meets the saddle. Even gel padding is only marginally better than foam. It's more important whether the plastic shell is completely rigid, which is not good, or whether it is flexible and held in shape by the two rails that the saddle is mounted on, especially if these rails are themselves flexible.

Some people swear by leather Brooks saddles, which work by the same principle except that the leather stretches more than plastic and so the rail mounting needs to be re-tightened occasionally. The leather needs to be rubbed frequently with oil at first so it is soft enough to change its shape to adjust to the shape of your pelvis, and must be protected from rain. Once you get past the initial months it's said to be the perfect saddle, but I prefer not to go through all the trouble.

One of the best saddles I have used is the regular racing Flite, which has next to no padding but a flexible shell and soft Titanium rails. I normally avoid the Titanium hype but this is a really useful application. Titanium is much softer than steel. Unfortunately you can't adjust the tension, so after a couple of years it sags and becomes unusable.

My favorite is the Selle Italia Turbo Matic 2, with its distinctive yellow/black rear end. It's the best of both worlds, and I have done many long tours with it.

The saddle height is very important. If it's too low, you have much less strength when pedaling, and if it's too high you'll rub your thighs sore. Adjust the height until you can pedal backwards with the heels of your shoes on the pedals, with fully stretched knees but still touching the pedal when the pedal is in the bottom position, without rocking your hips. The position must be exact to about five millimeters (1/5 inch). I prefer the standard angle where a bar laid on the nose and back of the saddle, parallel to the top tube, is horizontal, but some people prefer the nose slightly up or down.

Tell me if you found this information interesting or useful, or if you have comments.