Axles
Fork axles and thru-axles for mountain bike suspension forks — Maxle, Kabolt, Boost and non-Boost standards. The axle clamps your front wheel into the fork lowers, so match the thread pitch, axle length and hub spacing to your fork and wheel. Getting the right one is a simple compatibility exercise: there are only a few standards, and they're not interchangeable.
Which thru-axle standard does my fork use?
Modern MTB forks use one of three thru-axle standards: 15x100mm (non-Boost, legacy), 15x110mm (Boost, current standard for most trail/enduro/XC forks), and 20x110mm (Boost, DH forks and some older enduro forks). The first number is the axle diameter, the second is the hub spacing — the distance between the fork dropouts. Boost spacing (110mm) is now standard on everything except some XC race forks and older models.
What thread pitch and length do I need?
Beyond the diameter and spacing, you need to match the thread pitch. RockShox Maxle uses M15x1.5 threads. Fox Kabolt uses the same thread but a different lever mechanism. Thread length also varies — some forks have longer threaded sections than others. The safest approach is to match the replacement axle to your exact fork model and year, the same model-and-year rule that governs service kits.
OEM or aftermarket axle?
RockShox Maxle Stealth and Fox Kabolt are the OEM options — reliable and straightforward. Aftermarket axles from Robert Axle Project, DT Swiss and Wolf Tooth offer lighter weight (titanium or aluminium), tool-free operation, or different lever designs. Robert Axle Project also makes rack and trailer-compatible axles with secondary attachment points. For most riders, the OEM axle is fine; if you've lost yours or want a lighter one, the aftermarket options are worth a look.
What about quick release forks?
Some budget and older forks still use 9mm quick-release axles. These are lighter and easier to use but significantly less stiff than thru-axles. If your fork uses QR and you're upgrading, you'll need a new fork — there's no conversion kit from QR to thru-axle, and nothing in the fork parts and spares range will bridge the two.