Wheel axles

BMX wheel axles: the part that ties the hub to the frame

The axle runs through the hub and clamps into the frame dropouts or the fork legs. It takes the load as you leave the gate and keeps the wheel aligned on landing. An axle of the wrong diameter, too short or badly torqued, brings play, wheel misalignment and premature bearing wear.

Front axles and rear axles

A front axle works mainly in bending and is chosen first around the fork spacing. Hollow 7075 aluminium versions take weight off the wheel; solid chromoly versions accept harder clamping and forgive impacts better. The rear axle also carries the pedalling torque coming through the cassette driver: it is generally heavier and its shoulder must match the hub exactly.

10, 15 or 20 mm: how to choose

Diameter is not a free choice, it follows from your frame, your fork and your hubs.

• 10 mm: the historic standard, still dominant at the rear and on Micro to Junior bikes
• 15 mm: the stiffness-to-weight compromise now widespread at the front
• 20 mm: maximum stiffness, paired with the through-axle forks of the Pro classes

Measure the existing axle with a vernier caliper rather than trusting your eye: 10 and 15 mm look very alike once the hub is built into the wheel.

Compatibility: what has to match

Three dimensions govern fitment: axle diameter, overall length, and hub spacing (100 mm front, 110 mm rear on most race builds). The axle must protrude far enough for the nuts to bite, without binding against the dropouts. Check nut thread pitch too, specific to each hub brand, and the thickness of your frame dropouts. The specification of your BMX hubs and the reference of the cassette driver are the two things to have to hand before ordering.

Adaptors and conversion kits

Changing frame or fork does not mean buying new wheels. Adaptor bushings let a 20 mm hub sit in 10 mm dropouts, or a 15 mm hub run in a through-axle fork. Onyx kits cover the Ultra SS and Ultra ISO hubs, Pride offers its own for the Control range, Forward for the Joyride. It is the cheapest way to carry a bike through the classes.

Use by rider class

In Micro, Mini and Junior, the 10 mm axle is ample and makes trackside strip-downs easy. From Expert upwards, and above all in Pro and Pro XL, moving to 15 or 20 mm at the front is felt in the berms, where the front wheel works hardest. Keep a spare axle in the bag: it is a part that bends or picks up a damaged thread after contact.

The brands available

• Onyx: axles and conversion kits for Ultra SS and Ultra ISO hubs
• Pride: axles and adaptors for the Control range
• SD Components: 15 and 20 mm axles, precise machining
• ICE: axles for Tank hubs
• Meybo: aluminium axles, front and rear
• Box Components: axles and hardware for Quantum hubs

The BMX RACING advice

An axle is ordered on three pieces of information: hub brand and model, measured diameter, and the width between frame or fork dropouts. Send us those and we identify the exact reference, plus the bushings you need if you are changing standard. It is also a good moment to check the state of your BMX spokes. Dispatched within 24 to 72 hours and you can spread the cost over 2 or 3 payments available.