Cranks
Browse used BMX cranks for sale from riders across the UK. Most 20in bikes run 175mm three-piece chromoly cranks — two arms and a separate 19mm, 22mm or 24mm spindle — with 170mm and 165mm arms used by smaller riders and anyone chasing a little more pedal clearance. This category covers complete crank sets, single arms and spindles for street, park and race builds.
What length BMX cranks should I buy?
175mm is the standard on adult 20in bikes, and dropping to 170mm or 165mm shortens the swing and lifts the pedal a fraction further off the ground, which suits shorter riders and grind-heavy street setups. Construction matters more than length for durability: heat-treated tubular chromoly arms from Odyssey, Éclat and Profile Racing sit at the strong end, while the heavier one-piece and cast arms fitted to budget complete bikes bend sooner under the same abuse.
Which spindle size should I choose — 19mm, 22mm or 24mm?
All three are in use. The 19mm chromoly spindle is the traditional street size and takes the most punishment, 22mm splits the difference, and 24mm is usually paired with lighter arms and correspondingly smaller bearings. The choice normally follows the bottom bracket already in your frame, since the spindle diameter dictates the bearings; if you are starting from nothing, 19mm has the widest spread of used parts to pick from.
Cranks or bottom bracket — what am I actually buying?
Listings vary a lot. Some crank sets come with the spindle, bolts and bearings, others are bare arms. Read carefully, because a 22mm crankset will not run in a 19mm bottom bracket even when the frame shell is identical, and the bolts alone are an irritating thing to source. Checking the seller's other BMX components often turns up the matching kit.
What should I check on used BMX cranks?
Pedal threads first, every time — a stripped pedal thread is the most common way a crank arm dies, so ask for a photo with the pedals removed and look for chewed threads or a fitted insert. Then check the splines or bolt interface for rounding and slop, and look for cracks around the pedal boss and where the arm meets the spindle. Sight along each arm for a bend, check for fretting marks that show it has been ridden loose, and confirm the crank bolts are present.
Are used cranks worth it?
A three-piece set is one of the more expensive parts on a BMX, so used cranks with clean pedal threads and a straight spindle are genuinely good value at half of new or less. Buy new if the threads are marginal, if the bolts are missing, or if you need a spindle size that only comes as part of a full set — a repaired thread on the part carrying your whole weight is not a saving. Cranks stripped from a bike often list next to the bars and the drivetrain, which is worth watching for if you are rebuilding.