Many cyclists enjoy using bike trailers to haul cargo or kids, and Thule is a popular brand known for its quality trailers like the Cadence and Chariot models. These trailers typically come with the Thule ezHitch system, designed for easy attachment to most bikes with quick-release or solid axles. While Thule offers an adapter for thru-axle wheels, a common issue arises for e-bike owners. Many e-bikes, especially those with powerful motors, utilize robust 12mm solid rear axles. Unfortunately, the standard Thule ezHitch isn’t compatible with these larger axles, and Thule doesn’t provide a specific adapter for this size. This incompatibility is a significant drawback, as towing a trailer with the added power of an e-bike is incredibly convenient. Faced with this problem, I explored a DIY solution to modify the Thule ezHitch to fit my e-bike’s 12mm solid axle. Below, I’ll outline the steps I took to achieve this modification.
The standard Thule ezHitch is designed to work with conventional solid axles, which are typically around 3/8″ (approximately 10mm) in diameter. E-bikes, however, often require stronger rear axles to withstand the increased torque and power generated by the electric motor. These heavy-duty axles are frequently 12mm in diameter and are often paired with features like anti-spin washers to prevent axle rotation within the frame under load. For instance, my Juiced CrossCurrent e-bike uses an M12x1.25 rear axle, and similar 12mm axles are found on various Rad Power Bikes models and other e-bikes. The absence of a Thule adapter for 12mm axles creates a frustrating limitation for e-bike users wanting to utilize Thule trailers. To overcome this, modifying the existing hitch becomes a viable option.
Proceed with Caution: Modify at Your Own Risk
It is crucial to understand that the following modification is not endorsed or supported by Thule. Attempting this modification will almost certainly void your Thule warranty and carries potential risks of damage to your equipment or, more seriously, personal injury or even death. This guide is purely informational, detailing the steps I personally took. It is not a recommendation to perform this modification, nor is it a guarantee of safety or success. If you are not comfortable with DIY modifications or are unsure about your ability to perform this task safely, it is strongly advised to seek professional assistance or explore alternative trailer solutions.
The most straightforward approach to fitting the Thule ezHitch onto a larger 12mm axle is to enlarge the hitch’s axle hole. This can be accomplished by carefully drilling the existing hole to a slightly larger diameter. Stainless steel, the material of the ezHitch, can be drilled using a cobalt drill bit and a standard power drill. For this modification, I purchased a 1/2” cobalt drill bit from a local hardware store. A 1/2” drill bit measures 12.7mm, which is slightly larger than the 12mm axle. This slight increase in size provides a small margin for error and ensures the hitch will comfortably fit the axle. While researching this method, I found a helpful YouTube video from RadCity eBike Vlog demonstrating a similar modification for a different trailer brand, which can provide a visual guide to the process.
When drilling steel, it’s important to use a slower drill speed compared to drilling wood. Lower speeds minimize heat buildup, which can damage the drill bit and the material being drilled. Drilling through the stainless steel of the ezHitch took several minutes of consistent pressure and slow drilling. While it might be possible to use a standard steel drill bit, a cobalt drill bit is highly recommended due to its superior hardness and heat resistance, ensuring a cleaner cut and prolonging the life of the bit. My cobalt drill bit showed no signs of wear after this modification.
Once the drilling is complete, the modification is finished. The entire process is quick, taking approximately 5 minutes. The modified hitch is then ready to be installed on your e-bike. The axle on my Juiced CrossCurrent e-bike had sufficient length to accommodate the slightly thicker hitch without any issues. With the modified ezHitch installed, my Thule trailer now fits perfectly on my e-bike, and towing my child in the trailer has become a joy. The e-bike’s extra power is particularly beneficial when pulling a trailer uphill or over longer distances, making the e-bike and trailer combination an excellent pairing. Finding a solution to make my Thule trailer compatible with my e-bike has significantly expanded the utility and enjoyment of both.
2024 Long-Term Durability Update
Many have inquired about the long-term performance of this modification. I’m pleased to report that after over two years and more than 40 rides, the modified trailer hitch continues to function flawlessly. It has held up remarkably well, demonstrating the durability and effectiveness of this simple DIY fix.
