The chain disk
By MrFixie
Advice on choosing your chain disk
Chain disks or sprockets or chain wheels are the front part of the gear on a fixie. For a 42:15 gear, 42 would be the chain disk’s number of teeth. These “wheels with teeth” bolt onto the crank arms and convert your pedaling power to rear cog. The chain disk width is usually 3/32, and it can be use with 1/8 chains.
BCD is the bolt center diameter. The chain disk BCD must match the Crank Arm BCD for the two to properly connect with stack bolts.
