Bike Chain Basics - Page 1 of 3

Figure 1

Figure 1 - Two different sizes of bicycle chain

When creating your own human powered vehicles, a chain drive will likely be your chosen power transfer system, as it is an inexpensive, easy-to-install and highly efficient drive mechanism. Bicycle chains are fairly simple, requiring only one inexpensive tool to remove and attach links. Since a recumbent cycle will often require a chain that is one and a half to 3 times the length of a regular upright bicycle chain, some basics should be known, as you will probably need to create the chain for your vehicle.

There are two basic types of bicycle chain: single speed chain and multi-speed chain. Single speed chain is mainly used on kids' bikes, BMX bikes, coaster brake cruisers, and heavy cargo bikes. Multi-speed chain is used on standard speed bikes and mountain bikes that require the use of a front and rear derailleur to change gears. Both types of bicycle chain have a pitch of 1/2 inch (ANSI standard #40). This measurement indicates the length of the links. Although every type of bicycle chain and freewheel have a 1/2 in pitch, the width of chain varies quite a bit, from 3/32" to 1/8".

Single speed bicycle chain is wider, having a width of 1/8 inch. This type of chain will not fit a multi-speed freewheel nor will it fit properly through a derailleur cage. Multi-speed chain comes in various widths, with 3/32" being the most common size. Multi-speed chain is designed with a lot more side-to-side flex to allow it to function properly with a derailleur system. Flexibility is very important in a multi-speed system as the alignment of front and rear chain rings could be off by as much as 3 inches, depending on which gears are being used. Figure 1 shows the two common sizes of bicycle chain; 1/8" on the top and 3/32" on the bottom. At this angle, both chain types look very similar since you can only see the pitch, not the width.

Figure 2

Figure 2 - Single speed (top) and multi-speed (bottom)

Figure 2 gives you a much clearer view of the difference between a 1/8" single speed chain (top) and a 3/32" multi-sped chain (bottom). The multi-speed chain is obviously narrower to fit the narrower chain rings on a multi-speed freewheel, and it also includes a beveled edge on the inner link to allow for better meshing with the teeth when switching gears.

Figure 3

Figure 3 - A bicycle chain link tool

When bicycle building becomes your hobby, one of those "must have" tools will be a chain link tool as shown in Figure 3. For under $20, this small tool will give you a lifetime of service, able to break and rejoin any size of bicycle chain in a few seconds. The other method involves using a punch, a hammer, and a finishing nail, but I assure you, the chain link tool is so much easier and makes a worthwhile investment. To open a link, place the chain into the holder as shown in Figure 3, and then turn the vice handle clockwise to press out the link pin.

Figure 4

Figure 4 - Removing the link pin

Figure 4 shows the link pin pushed out by the chain link tool after turning the handle around a few times. This tool makes adjusting a chain pretty much effortless which is a good thing since you may have to adjust a long recumbent chain on a new project several times to get it right.

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