BMX bikes use three differing kinds of crank – one-, two- and three-piece. One-piece are the most basic and feature a single piece of metal to form both crankarms and the axle. Two-piece versions are similar to a lot of mountain bike cranks, with the axle bonded to the driveside crankarm.
Finally, three-piece cranks are considered the most desirable due to their increased strength. Bottom brackets can be the first thing to go on BMX bikes, due to the impact forces channelled through them. There are several styles available, depending on the style of crank, but theyʼre relatively inexpensive to replace.
Freestyle BMX bikes tend to feature ʻmicro driveʼ gearing (a relatively small front chainring and a correspondingly diminutive rear cassette). This is partly for aesthetic reasons but also allows for improved ground clearance during tricks.