Upgrading your Thru-Axles? Read our Bicycle Thru-Axle Measuring Guide!
How to Measure Your Bicycle’s Thru-Axles
A frequent question we get is:
“I have this bike — do you have a suitable thru-axle for me?”
Unfortunately, there are so many variations that it’s nearly impossible for us to maintain a complete list of thru-axles for every bike model. Some websites do offer such lookup services, but the best way to ensure a perfect fit is to measure your own thru-axles.
Download a one-pager guide here, or read on for more details.
The Variables of Thru-Axles
Before we begin measuring, let’s understand a few basics.
You’ll often see hub standards like 12×100 (front) or 12×142 (rear).
- 12 → axle diameter (in mm)
- 100 / 142 → dropout spacing (in mm)
However, thread pitch and actual axle length are not standardised and vary by brand and even by model year. That’s why measuring your thru-axle is so important.
You’ll need to check four key variables:
- Axle Length (front and rear)
- Axle Diameter
- Thread Pitch
- Head Contact Area (flat or convex)
1️⃣ Measuring Axle Length
Remove your existing axle and measure its total length excluding the axle head and any spacers.
If your setup includes a spacer, measure the width of the spacer separately — most stock axles don’t include one.
2️⃣ Measuring Diameter
Most modern thru-axles are M12, meaning the nominal (design) diameter is 12 mm. However, actual thread diameters are intentionally smaller than the stated size to allow for any variations in the internal thread it is screwing into. This is done in accordance with strict metric thread tolerances.
Examples for an M12 Thread:
- External thread (bolt/axle): 11.85–11.95 mm (slightly smaller)
- Internal thread (nut/frame insert): 12.05–12.15 mm (slightly larger)
For instance, Sixweel Titanium Axles are manufactured to a tolerance of ±0.01 mm. A testament to their fine finish and quality.
To measure the diameter, simply measure the threaded portion (not anywhere else!).
In this example above, we measure the axle thread as 11.86mm - close to 12mm. We consider this as M12.
3️⃣ Measuring Thread Pitch
Thread pitch refers to the distance between threads. Unfortunately, it’s not standardised across the bike industry.
Below are 3 common thread pitches for M12 axles:
1.0mm Thread Pitch (for Specialized)
1.50mm Thread Pitch (for Giant)
1.75mm Thread Pitch (for Canyon). Notice the wider spaces between each thread compared to 1.0mm
Even the same model can change over the years — for example, older Giant Defy frames used a 1.0 mm pitch, while newer ones use 1.5 mm.
To measure pitch, you can use a thread gauge (ideal), or do it manually:
- Use a ruler.
- Count the number of thread peaks over a 10 mm section.
- Divide 10 by that number — the result is your thread pitch.
Example: 10 mm ÷ 10 threads = 1.0 mm pitch
Image Credit: https://www.omnicalculator.com/construction/thread-pitch
4️⃣ Thru-Axle Head Contact Area
For aerodynamic or aesthetic reasons, many modern bikes recess their thru-axles into the fork or dropout.
This introduces another variable: the head contact shape.
There are 2 Common Types - Flat and Conical Head:
Flat Head - typically sits slightly proud of the front fork/rear dropout.
Flat Head + Conical Washer - Uses a conical washer to fit within recessed frames for a clean look.
If your axle uses a cone spacer, measure:
- The outer diameter,
- The cone angle, and
- The height of the spacer.
You’ve Got the Measurements — Now What?
Well done! With these three measurements — length, thread pitch, and head shape — you’re ready to choose your new thru-axle.
Quick Checklist:
- ✅ Thread pitch: must match exactly.
- ✅ Head shape: flat or convex (must fit your frame design).
- ✅ Length: too short = unsafe. Slightly too long can be fine with spacers, though it may look less tidy.
Ready to Upgrade?
Explore our range of titanium thru-axles — from ultra-lightweight options with premium finishes to practical designs with hidden levers.