BMX cranks for race and freestyle

Why cranks specific to BMX?

A BMX has only one gear: all the rider's power goes through the cranks, during gate starts, accelerations and landings that would bend a road chainset. BMX cranks carry only one sprocket, their arms are designed to resist flex, and their spindle and bottom bracket standards are their own.

Race or freestyle: two-piece, three-piece or one-piece cranks?

In BMX racing, most cranks are two-piece: the 24 mm spindle is attached to the drive-side arm, the other arm clamps onto it, and a 4-bolt spider with a 104 mm BCD takes the chainring. Forged aluminium makes them light and stiff for sprints.

In freestyle, whether street, park or dirt, three-piece cranks in chromoly steel dominate: two arms fixed to a 19 or 22 mm splined spindle, onto which the sprocket slides. Entry-level BMX bikes often keep a one-piece crank, made from a single piece, which takes pedals with a 1/2 inch thread instead of 9/16.

Spindle and bottom bracket: the dimensions to check on your frame

BMX uses four types of bottom bracket: Mid, the most common in freestyle, with 41 mm bearings pressed into the frame; American, with a larger diameter (51 mm), inherited from one-piece cranks; Spanish, smaller (37 mm); and the threaded BSA bottom bracket, common in racing. Note the type on your frame, then the diameter of the crank spindle, 19, 22 or 24 mm: the bearings must match both.

What size BMX cranks do you need?

Measured from the centre of the spindle to the centre of the pedal hole, crank length follows the rider's height: from 140 mm for the youngest racers to 180 mm for tall riders. A long crank gives leverage at the start, at the cost of a slower cadence and a pedal closer to the ground in corners. In freestyle, common lengths range from 160 to 175 mm.

Sprockets, chains and cranks for other disciplines

Choose the sprocket from our BMX sprockets according to the spider's BCD or the spindle diameter; chain and rear cog are gathered in BMX chains, cogs and freewheels. For a bike with several gears, see bike chainsets and their standards.

Which BMX crank brands to choose?

Box, founded in California by former BMX racer and mountain biker Toby Henderson, offers the Box Four, a two-piece crank in cold-forged aluminium supplied with its threaded bottom bracket, and the Box Three.

Avian designs its Cadence for experienced racers: hollow forged aluminium arms, a 24 mm chromoly spindle, lengths from 170 to 180 mm in 2.5 mm steps.

Insight follows the racer at every age: the MX4 comes in 140 to 165 mm, the RLC in 165 to 180 mm.

Mission makes the Transit V3 for freestyle, in seamless 4130 chromoly tubing on a 19 mm spindle, which can be set up on the right or the left.

Eclat, a parts brand born in Cologne in the Wethepeople circle, fits the Spire with a hollow 22 mm spindle with 48 splines.

BMX cranks on sale

Cranks from previous series join our BMX clearance, and recent references our new arrivals. During the winter break in racing, Black Friday and the winter sales help you prepare for the new season.

Frequently asked questions

Which bottom bracket for my BMX frame?

Look at the frame's bottom bracket shell: if it is threaded, it takes a BSA bottom bracket; if it is smooth, its inside diameter tells American, Mid and Spanish apart. The bearings then follow the spindle diameter.

Can you fit MTB pedals to BMX cranks?

Yes on two or three-piece cranks, whose 9/16 inch thread is the same as that of MTB and road pedals. A one-piece crank needs 1/2 inch pedals. Never force a thread that resists.

What do RHD and LHD mean?

RHD means right-hand drive, the classic set-up, and LHD left-hand drive, chosen by some street riders to free up the right side for grinds. Cranks, hub and cog must then follow suit.

What crank length for a child in BMX racing?

Cranks of around 140 to 155 mm suit the youngest riders, on mini or junior frames. If it is too long, the crank hampers leg rotation and touches the ground in corners.

Should you change the sprocket at the same time as the cranks?

Not necessarily. In racing, a 4-bolt chainring with a 104 mm BCD fits any crank with the same BCD. In freestyle, it must accept the diameter of the new spindle, with a reducer if needed.