BMX Cranks Over the years BMX Cranks have probably been the biggest changing and developing after market part. Cranks are most commonly made with a 3 piece design with a splined spindle, A splined spindle (axle) saves the need to have a pinch bolt to get rid of the messy look and create a flush feel to the bottom of your bike. Crank axle sizes come in either 19mm or 22mm, you'll have to check your bottom bracket size to before buying new cranks. Another feature which a lot of manufactures are bringing in is the titanium axle, although this is a more expensive option it saves a dramatic amount of weight though out your bike. If you're looking to add some after market cranks to your complete bike or just looking for some new ones then check out our collection.