Thru-axles are becoming more common on newer bikes, especially on bikes that have disc brakes.
If you have a thru-axle bike, then you’re probably here because you’re trying to figure out how to attach a bike trailer to your thru-axle or disc brake bike.
Trust me—I’ve been there!
This guide will make it easy for you to identify the size of your bike’s thru-axle and exactly where to get the right adapter for your bike trailer.
An adapter can be purchased to attach any bike trailer to a thru-axle bike for around $60. In order to find the right thru-axle adapter for your specific bike, you first need to identify these three things:
- Axle length
- Thread pitch
- Axle diameter
Below I’ll explain how to find each of these.
You can purchase the correct thru-axle adapter size for around $60 using the links below, depending on your bike’s thru-axle size.
How to measure your thru-axle
Most of the confusion around thru-axles and bike trailers comes down to the fact that there are so many different sizes of thru-axles.
Here’s how to measurements you will need in order to find the correct thru-axle adapter for your bike:
1. Axle diameter
The axle diameter measures the diameter around the axle. Most thru-axles are 12mm, so it’s probably safe to assume your thru-axle is 12mm.
2. Axle length
The axle length measures the distance (usually in mm) from the head of the axle to the end. You will need to know your bike’s axle length in order to purchase the correct thru-axle adapter.
3. Thread pitch
The thread pitch measures the distance between each individual thread. You will need to know your bike’s thread pitch in order to purchase the correct adapter for your bike trailer.
How to quickly find the size of your bike’s thru-axle
There are three ways you can try to identify your bike’s thru-axle size:
- Remove the thru-axle from your bike’s wheel and check the sides for the dimensions.
- Check your bike’s user manual
- Measure the dimensions manually using the methods in the above section
Where to buy the right thru-axle adapter
Here is a list of many thru-axle adapters based on your trailer brand and your bike’s thru-axle size:
|BIKE TRAILER BRAND||AXLE LENGTH||THREAD PITCH||AXLE DIAMETER||LINK TO PURCHASE|
|Burley||142 to 148 mm||1||12||View on Amazon|
|Burley||142 to 148 mm||1.5||12||View on Amazon|
|Burley||142 to 148 mm||1.75||12||View on Amazon|
|Burley||197 mm||1.5||12||View on Amazon|
|Burley||197 mm||1.75||12||View on Amazon|
|Thule||148 mm||1||12||View on Amazon|
|Thule||152 to 167 mm||1||12||View on Amazon|
|Thule||159 to 165 mm||1.5||12||View on Amazon|
|Thule||162-174mm||1||12||View on Amazon|
|Thule||172 to 178 mm||1.5||12||View on Amazon|
|Thule||192 to 198 mm||1.75||12||View on Amazon|
|Thule||209 mm||1.5||12||View on Amazon|
|Thule||217 to 229 mm||1||12||View on Amazon|
|Thule||217 to 229 mm||1.75||12||View on Amazon|
|Thule||229mm||1.5||12||View on Amazon|
|Instep||Any||Any||Any||Adapter not needed|
|Schwinn||Any||Any||Any||Adapter not needed|
|Other brand||Other length||Other pitch||Other diameter||View on Robert Axle Project|
Burley thru-axle adapters
There are several thru-axle adapters available by Burley, depending on the size of your thru-axle. If you cannot find the right size for your specific thru-axle using the table above, then be sure to check out the thru-axles provided by the Robert Axle Project website.
Here’s a helpful video to show how to attach a Burley thru-axle adapter:
Thule thru-axle adapters
Thule provides a ton of thru-axle adapters for just about every size of thru-axle in existence. You can use the table above to find the correct size adapter for your bike trailer.
If you cannot find the right size for your specific thru-axle using the table above, then be sure to check out the thru-axles provided by the Robert Axle Project website.
Here’s a helpful video to show how to attach a Thule thru-axle adapter:
Other bike trailer brands
If you have a bike trailer by Hamax, Schwinn, Instep, Aosom, or any other brand, then you can either try a Thule thru-axle adapter or check out the Robert Axle Project website.
Adapters by the Robert Axle Project are made specifically for bike trailers, and are compatible with Hamax, InStep, Schwinn, Thule, Burley, and several other brands.
You can purchase thru-axle adapters from The Robert Axle Project website, which sells sturdy adapters specifically designed for bike trailers.
Here’s a helpful video to show how thru-axle adapters work:
Why are bike trailers not compatible with thru-axle bikes?
The reason almost all bike trailers are not compatible with thru-axle bikes right out of the box is that thru-axles are fairly new compared to the standard quick-release skewers.
Bike trailer manufacturers designed the trailer hitch coupler system with the quick-release in mind, which unfortunately means that the original design of many couplers does not fit the thru-axle.
The good news is that some bike trailer companies are catching on and have decided to make their coupler hole a little bigger to accommodate the thru-axle size. Notably, Schwinn and Instep have made a drastic change to their standard coupler attachment in recent years that allows for a thru-axle to pass through the coupler hole. It was a bold move on their part to upgrade their coupler, but it’s good they did because now they have created the most “universal” coupler on the market. Not only that, but Swhinn has come out with some very solid bike trailers (like this one) for a super affordable price (compared to other brands).
It’s interesting to me that Thule and other big bike trailer brands have not yet caught on to changing their standard hitch coupler to accommodate thru-axles, but they do a very good job at providing many different types of thru-axle adapters for all sizes.
What makes thru-axles better than quick-release skewers?
Many newer bikes now use a thru-axle system, especially mountain bikes and bikes with disc brakes. The reason for this industry-wide change from the traditional quick-release is largely due to many ongoing lawsuits surrounding the quick-release skewer.
One of the most notable lawsuits resulted in the very popular bike brand Trek recalling a certain disc brake bike because the quick-release lever was reportedly getting caught in the disc rotor when the lever was left open while riding. This incident seemingly taught the industry that the safest system for disc brakes is thru-axle, rather than quick-release.
Another primary reason for the switch from the quick-release to the thru-axle is because the thru-axle is stiffer than the quick-release. The stiffness of the thru-axle in turn gives more sturdiness to the form of the bike. Quick-release skewers have been known to bend and offer less stiffness to the bike’s wheel axle because of how thin they are.
There is a way to attach any bike trailer to any thru-axle bike. It might be a bit confusing and even overwhelming at first, but as soon as you can figure out what size thru-axle you need, you will know exactly where to get the right adapter using the links provided in the above table.
Once you get the correct adapter, you’ll be on your way to experiencing all the benefits of bike trailers!
Need help finding the right bike trailer?
If you need help finding the right bike trailer for you, my recommended trailer for most people is the Swhinn Joyrider, which is an affordable double-seater that converts beautifully to a stroller. Check out my full review with photos here.
Check out the Ultimate Guide to Buying a Bike Trailer for more help with choosing a trailer. I also have compiled a list of the top bike trailers for every common situation, which you can check out here.