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Drivetrain
The complete BMX drivetrain in one place: three-piece cranks and crank arms, Euro, Mid and Spanish bottom brackets, chainrings and one-piece sprockets, screw-on freewheels and cassette cogs, 1/8" and 3/32" chains. Parts from Inspyre, Tangent, Rennen, Box Components and Supercross, with the build advice that goes with them.
A BMX race drivetrain, part by part
On a bike with no derailleur, everything comes down to a single gear: the chain links a chainring or a one-piece sprocket at the front to a cog at the rear, and that one ratio has to work for the gate start as much as for top speed at the bottom of the first straight.
What this category covers
- Cranks and crank arms: three-piece forged aluminium or carbon arms, 19, 22 or 24 mm spindles, lengths from 145 to 180 mm.
- Bottom brackets: threaded Euro BB in 68 and 73 mm, Mid BB 41 mm, Spanish BB 37 mm, American BB 51 mm.
- Chainrings and sprockets: chainrings bolted to a spider on a given BCD, one-piece sprockets machined from a single billet.
- Rear cogs: screw-on freewheels threaded onto the hub, or cogs fitted to a cassette driver.
- Chains: 1/8" on the 12.7 mm pitch, the track standard, or the narrower and lighter 3/32".
Ratio, gear inches and rollout
Gearing is quoted first as a ratio: 44x16 means 44 teeth at the front and 16 at the rear, or 2.75. Multiplied by the wheel diameter, that ratio gives roughly 55 gear inches on a 20" wheel and close to 4.4 m covered per crank revolution — the rollout. A 43x15 (2.87) lengthens the gear; a 41x16 (2.56) shortens it and favours acceleration.
Matching the gear to the rider and the track
Micro and Mini riders turn short ratios, often between 2.4 and 2.6, on 145 to 155 mm crank arms. Junior and Expert sit closer to 2.6 to 2.8, Pro and Cruiser above that. A short track with several re-accelerations calls for a shorter gear than a fast track with long straights: plenty of riders keep a second cog in the race bag to adjust to the layout.
Checking compatibility before you order
Three measurements usually settle it: the standard and shell width of your BMX race frame, the crank spindle diameter (19, 22 or 24 mm), and the type of rear hub on your wheels — freewheel thread or cassette driver. Chain width then has to match the tooth profile at both ends.
The BMX RACING advice
Being multi-brand, we compare standards rather than push one range. Tell us the frame brand and year, the rider category and the tracks you ride: we confirm the ratio and the dimensions before dispatched within 24 to 72 hours, with you can spread the cost over 2 or 3 payments. Remember to match the build with your brakes.
To turn a tooth pairing into gear inches and metres, our BMX gear ratio chart gives the maths and the benchmark figures for each wheel format.
Questions fréquentes
How do I choose my BMX Race drivetrain?
It all starts with the gearing: a chainring paired with a sprocket sets your gear development. A 44/16 setup is a versatile standard; you then adjust it to suit the track and the rider's power.
Chromoly or aluminium for drivetrain parts?
7075 aluminium is light and favoured in competition, while chromoly is tougher for young riders or intensive training. In BMX Race you want the best weight-to-stiffness ratio.
Is shipping free?
Yes: shipping is free within mainland France from €99 of purchase. Below that, the cost is shown at checkout according to weight and the chosen shipping method.
Can I pay in instalments?
Absolutely. You can pay for your purchases in 2 or 3 instalments with Alma, completely securely. The option appears automatically at checkout.
How long do I have to return an item?
You have 14 days after delivery to change your mind. The item must be new, unfitted and in its original packaging to be returned or exchanged.
Do you deliver to the French overseas territories (DOM-TOM)?
Yes, we also ship to the French overseas territories (DOM-TOM). Times and costs depend on the destination and parcel weight; the exact amount is calculated and shown before you confirm your order.