Interesting Facts About Thru Axles

Important information on how to correctly determine the installation length [mm] of your thru-axle

We frequently receive inquiries asking why our thru-axle lengths aren’t selectable in our configurator until 155 mm, and why Syntace X-12 thru-axles aren’t selectable until 150 mm.

However, many customers often mistakenly rely on the " 12 x 142 " or " 12 x 148 " markings on the thru-axle.

However, this marking only indicates the hub width (142 mm or 148 mm); the number 12 refers to the outer diameter of the thru-axle (ø12 mm).

Hub width refers to the inside dimension of the rear wheel rim or the outside dimension of the rear wheel.

However, the key factor is the “INSTALLATION LENGTH” [mm], which is calculated as the sum of the hub width and twice the length of the frame stays.

Types of thru-axles: 

• Standard thru-axle with a flat stop at the head [Figure 1]
• Syntace thru-axle (X-12) with a tapered ring, usually slotted at the head [Image 2]

Thread types:

• Flat threaded outlet [Figure 3]
• Tapered threaded end (centering tip)  [Figure 4]

Thread sizes:

• M12 x 1.00 Standard (always used with Syntace X-12 thru-axles)
• M12 x 1.25 Custom size (rather rare)
• M12 x 1.50 Standard
• M12 x 1.75 Standard

Determining the installation length: [mm]

• Standard thru-axles are always measured from the inside of the flat head [Figure 1]to the end of the thread (axle) [Figure 3]. 
• Syntace (X-12) thru-axles are always inserted from the tapered ring [Figure 2] to the end of the thread (axle)  [Image 3] or, in the case of a threaded end with a centering tip, only up to the last thread  [Figure 4]  excluding the centering tip.

Please note that you must select the appropriate thru-axle in the correct menu under:

Select "Adapters & Axles". 

You can also use our measuring template as a PDF.