Also called a front sprocket. Comes in varying tooth counts. The tooth count will effect how hard or easy the bike pedals (more= harder, less= easier). The center whole can vary in size, some are smaller not intended for 1 piece cranks but the hole can be filed bigger to fit. Chainwheels also come in varying widths. 1/8" is typical for a single speed or internal gear bike. The smaller 3/32" is used for multispeed (derailer) bikes. The bigger 3/16" require a big heavy duty chain and are made for bmx/freestyle bikes.

Cranks can come in 1, 2 or 3 piece. The pieces of a crank are the left and right crank arm and the spindle. A 1 piece the crank arms and spindle are all one. Crank arm lengths can vary. The crank arm may be drilled and threaded for either a 1/2" or 9/16" pedal. Typically cruisers have a 1 piece crank that accepts a 1/2" pedal. The crank arm is held in place in the bottom bracket with a nut that is reverse threads.

Chains come in 3 sizes (width) 3/32, 1/8 and 3/16 . The size of chain will be determined by the chainwheel or sprocket. Generally singlespeed cruisers will take the middle size (1/8). The smaller chain is for multispeed bikes that use a derailer and the bigger, heavy duty for freestyle and bmx.