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The Daily Insight

What size thru-axle do I have?

Author

Christopher Pierce

Updated on February 28, 2026

For a front thru-axle, this is measured from the inside to inside of your fork. For a rear thru-axle, this is measured from the inside to inside of your frame at the drop-outs. The O.L.D. measurement is listed for many thru-axles, but isn’t necessary if you know the overall length.

What size is a standard bike axle?

At the front, road bike thru-axles are now pretty much standardised at 100mm long by 12mm wide (although some early thru-axle road bikes had 15mm diameter thru-axles). Rear thru-axles usually measure 142mm long and have a 12mm diameter, but you used to be able to find a few bikes with 135mm thru-axles.

What do you mean by thru-axle?

A thru-axle (TA) is a wheel attachment system that secures a wheel on a hub between a pair of dropouts on a bicycle frame or fork. The thru-axle threads directly through the fork/frame holes and into the wheel hub, which makes the wheel secure from detaching.

Are all bike axles the same?

But things like dropout design, thread pitch and the overall length of the axle differ between makes, even with the same axle spacing, so thru-axles are not always cross-compatible between brands.

What is 15mm thru axle?

15mm thru axle uses a different connection on the fork where the axle of the wheel allows a 15mm bolt to go through it. Same concept for a 20mm thru axle. Some wheel manufacturers have adapters that allow you to use the same wheel with the different fork hub standards by swapping out the axle ends.

How do you identify a Eaton axle?

Axle Housings are identified by the specification number stamped on the rear right hand side of the axle housing. This number identifies all components of the axle as built by Eaton, including OEM special requirements such as yoke or flange.

Can I use quick release to thru axle?

The best and easiest solution is to swap out your quick release fork for a thru axle fork. In most cases, you will also need a new front hub that is compatible with thru axles. 15 mm is the most common diameter for front thru axles. There are also adapters that allow you to use a thru axle hub in a quick release fork.

Can a 12x100mm front hub be used with a thru axle?

For use with 12 x 100 mm front hubs Allows the use of modern thru-axle wheels in forks designed for quick-release compatible hubs 100 mm front hub spacing only CNC-machined AL-6061 Compatible with most thru axle hubs-verify with hub manufacturer Problem Solvers Thru-Axle/QR Adaptor Front Axle Conversion Kit UPC: 708752201385

What size axles are in a Sun Ringle front axle conversion kit?

Item Specifications Front Axle Type 15mm Thru Axle Sun Ringle SRC/SRX Front Axle Conversion Kit UPC: 844171059654 End cap kits to accommodate the use of QR, 15mm, or 20mm axles with Sun Ringle SRC or SRX style hubs. Item Specifications Front Axle Type 20mm Thru Axle Sun Ringle SRC/SRX Front Axle Conversion Kit UPC: 844171059661

Can you convert a QR axle to a 12mm axle?

Converts from QR to 12mm thru axle Not compatible with Torch Mountain or Fat Bike hubs End caps are not compatible with Road Centerlock hubs Includes a pair of end caps Industry Nine Torch Classic CX/Road End Cap Conversion Kit Front Axle Conversion Kit

What is the UPC for Stan’s NoTubes front axle conversion kit?

Front end cap conversion kits for NoTubes 3.30 hubsReplacement/conversion end caps for NoTubes 3.30, 3.30Ti front hubs and ZTR front hubs with silver end caps Stan’s No Tubes 3.30 Front Axle Conversion Kit UPC: 183720000892