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Chainwheels, Cogs, and ChainsIn front, there are either two or three chainwheels. The innermost, smallest chain ring is intended for spinning up steep hills. It's also called granny gear, presumably to indicate who would need one. I prefer three chain rings on road bikes because I am over 60 and live in Colorado, which has steep hills and mountains.Chain line means that a chain should not run from an inner cog to an outer chainwheel or vice versa. Usually cassettes from one vendor cannot be mixed with components from another vendor. Chains appear to be the most neglected part of the typical bicycle. It seems that some bicycles I see have not been lubricated nor cleaned for years. Unlubricated chains squeak pitifully, make pedaling much harder, and destroy chainwheels and cogs, which are much more expensive to replace than just replacing the chain. 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 can be stretched. This means that the distance between two chain links no longer matches the distance between the two chainwheels 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 roll off the cog or chainwheel smoothly. Instead the chain will be grabbed by the "shark fin". The insidious part of this problem is that you don't notice it until the cogs you use most are already destroyed. Replacing the chain will make matters worse because now all links of the chain get hooked by all the "shark fin" teeth of the cog simultaneously, making the chain skip. This makes the cog unusable. The only option at this point is to replace all the worn cogs and the chain. To prevent this from happening, it is important to clean and lubricate the chain frequently, at least every two to three weeks, more often when riding in wet weather or a dusty climate. Before lubricating the chain, it must first be cleaned with an old T-shirt. You can run the chain through the t-shirt, but it's really better to clean each link individually (try using Q-tips to get the dirt from each link). 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 thoroughly, spin the chain for some time, and 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. Also, don't use motor oil because motor oil is designed to work in certain (hot) environments only. Grease doesn't work well because it won't reach the critical parts. 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. Content by Thomas Driemeyer, www.bitrot.de
Edited by Reg Gupton, gupton@growthseminars.com
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