How to Measure an Axle?

How to Measure Your OEM Axle

This section explains how to measure your original equipment manufacturer (OEM) axle. If your original axle is missing, you will need to contact your frame or fork manufacturer and ask for four key dimensions. To order a replacement axle, you need to know the following information: axle diameter, axle length, thread pitch, and thread length.

Look for Markings

Before attempting to measure your axle, check for markings on it. In many cases, the dimensions are laser-etched onto the axle. Your frame or fork manufacturer should also be able to provide these measurements.


 

Find a Metric Ruler

Thru-axles are measured in millimeters. Use a metric ruler or a set of calipers.


 

Measure Axle Diameter

Your axle diameter will be 12, 15, or 20 millimeters. Axles with 15mm and 20mm diameters are typically used for enduro and DH forks. Use a ruler or calipers to confirm the axle diameter.


 

Measure Axle Length

Measure the axle length, excluding the head or washers—only measure the axle itself. The replacement axle should be within 1-2mm of the original axle length. If your axle falls between two sizes, it's best to choose the longer threaded option.


 

Measure Thread Pitch

Thread pitch refers to the spacing between threads. To determine the pitch, count the number of threads within a 10mm section. 10 threads indicate a P1.0 pitch, approximately 7 threads indicate a P1.5mm pitch, and slightly less than 6 threads indicate a P1.75mm pitch. If you have difficulty counting, consult your frame manufacturer.


 

Measure Thread Length

Measure the total length of the threads on the axle. The replacement axle should have the same or a longer thread length. You should now have all the measurements needed to order a replacement axle. To accurately measure the thread, start from the beginning of the threads or the end of the axle, using the longer measurement.


 

Is It a Syntace Axle?

If your axle has a tapered washer, then it is a Syntace axle. These axles typically have a fine-thread pitch of P1.0.