How To Identify Your Bike Wheel Axle

A wheel axle: nothing could be simpler, right? A threaded rod that allows you to fix the wheel to the bike! But did you know that there are several types of wheel axles, several diameters, several threads, and several lengths? Identifying your wheel axle is essential for changing a wheel , replacing a nut, or a quick-release wheel. But also to put a wheel lock, install a Follow Me or a trailer hitch. 

We explain how to identify your bike wheel axle!

Measure a bicycle wheel axle: type of clamping, diameter, thread, and length

Types of bike axles

Solid axle or bolt axle

The solid axle is a classic in the world of cycling: the threaded axle protrudes from each side of the hub to allow tightening with two bolts.

Quick-release hollow axle

The quick-release system consists of a hollow axle, a rod with a lever on one side and a nut on the other. It allows the assembly and disassembly of the wheel without tools.

Thru Axle

The thru axle (called “Thrue-Axle”) is not integral with the hub, unlike other types of axles. It passes through the fork and the hub and is removed laterally to free the wheel.

The diameter of the axis

The diameter of the axle is essential information to identify your bike wheel axle! There are several standards, depending on the types of axes. A simple caliper allows you to know the diameter of the wheel axle of your bike. Here is a quick summary of the most common diameters:

Solid axle or bolt axle:
9 mm
10 mm
12 mm
14 mm

Be careful, some specific hubs including integrated gear hubs (Sturmey, Nexus, SRAM) do not necessarily have the same diameter. The axle can thus be 5/16 ″ (7.94 mm) or 3/8 ” (9.52 mm). This is important information for replacing wheel nuts for example!

Quick-release hollow shaft:
9 mm
10 mm

Thru axle:
12 mm
15 mm
20 mm

The length of the axis

You must know the length of the axle of your wheel if you plan to replace the axle or the quick coupler. You just need to measure the length of the axis with a tape measure or ruler. Note that the length of the front wheel axle is always different from the length of the rear wheel axle!


Pay attention to the thread on your bike! In the world of the cycle, we use the American thread, and not a metric thread. A “classic” hardware bolt is therefore incompatible with your bicycle wheel axle, for example. This means that the distance traveled by the nut in relation to each turn of the screw, in other words, the screw pitch is 1 mm against 1.25 mm for the metric standard. 

Screws and nuts for cycles have a smaller thread, which makes them easy to recognize.

A trick to identify a thread:

Measure the number of threads over 10 or 20 mm, then divide it by this number to find the size of the thread. For example: you have 10 threads in 10 mm and a diameter of 9 mm, you have an axis of M9 x 1.

Be careful, it is possible (but not very common) to meet bicycles with a pitch of the wheel axle of 1.25 and not 1.

Identify your wheel axle to put a wheel lock

Do you want to install a bicycle wheel lock  ? The previous items will help you identify the model you need. The bicycle saddle and wheel lock – Tranz-X is designed for quick release wheels. The front-wheel axle must be 110 mm and the rear wheel axle 145 mm. It is necessary to replace the quick coupler assembly on each wheel.

Identify your wheel axle to put a Follow Me or a trailer hitch

If you plan to mount a Follow Me or a trailer hitch, identify your wheel axle carefully before purchasing the adapter for towing bikes! Measure the diameter of your axis well as well as the screw thread of your axis to avoid surprises.

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