Mountain Bike Thru Axle Sizes

Ensure your rear hub is the correct size to fit your frame.

Mountain bike thru axle sizes.

Thru axles are commonly 12mm 15mm and 20mm in diameter. You can see more details about these measurements below. Using a tape measure measure inside width of frame fork where hub contacts frame fork. A guide to mountain bike axle standards 1.

142 x 12 thru axles are all the rage now. 15x100mm 15x110mm boost and 20x110mm the first number refers to the axle diameter while the second refers to the dropout width of the bike. Cysky bike axle quick release skewer front rear bicycle axle wheel hub fit for road bike mountain bike mtb bmx 1 pair 3 9 out of 5 stars 325 11 99 11. Spacing on these is 142mm wide with an axle diameter of 12mm.

Plus there are additional lengths for split pivot bikes and trek boost abp. Boost being newer isn t as much as a clusterfuck. This is done via visual reference. Boost gives a 148 x 12mm spacing which allows for the hub flanges to be further apart which gives a potentially stronger and stiffer rear wheel.

The diameter of the thru axle there are two common sizes. The standard mtb rear axle dimensions are 135x5mm for a qr rear hub but jump and gravity bikes may use wider and thick axles for extra strength and stiffness with the available sizes being 135 10 142 12 150 12 157 12 and 165 12. Thru axle hub ta skewer hub qr step 2. Determine if your frame fork uses a thru axle ta or skewer qr.

In this example 15mm is the diameter 100mm is the o l d 127mm is the overall length and 1 5mm is the thread pitch. 15 x 100mm 127 length 1 5. Skewers are almost always 5mm in diameter. Most thru axles are described by four measurements and you might see them described something like this.

Early cyclocross bikes borrowed the 15mm front thru axle diameter but as disc brakes became more common on drop bar bikes they all standardized to 12mm. The hub axle which was 9mm in diameter. They essentially operate the same as front thru axles on the rear of the bike. Old quick release hubs and 142 x 12mm thru axle hubs have the same widths between the hub flanges so there is no change in terms of hub flange positioning and wheel strength and stiffness.

Rear thru axle from my evil following uses a 12 x 142mm m12 x 1 5mm thread pitch shimano e thru standard. Traditionally frames and forks had slotted dropouts. 180mm length 20mm thread length. When mountain bikes first went to thru axles the standard was 12 142 which was the same effective width as the quick release hubs they replaced.