Universal Bike Trailer Hitch Coupler vs EUNORAU M12 to M10 Trailer Hitch Adapter

These are not rivals; they solve different problems. The universal U-bolt coupler is a general-purpose hitch for standard bicycles with quick-release or solid axles up to 12.2 mm, and it ships as two sets so you can leave one on each bike. The EUNORAU adapter is a single-purpose threaded part that converts an M12 hub-motor axle to an M10 trailer mount, and it only fits Eunorau ebikes such as the DEFENDER-S, UHVO, MAX-CARGO and G30 CARGO. Buy the universal kit for a normal bike; buy the EUNORAU part only if you have a hub-motor ebike with an M12 axle and an M10 trailer.

• Choose the Universal Bike Trailer Hitch Coupler if you have a standard bicycle, mountain bike or e-bike with a quick-release or nutted axle up to 12.2 mm and want a clamp-on hitch you can move between bikes.
• Choose the EUNORAU M12 to M10 adapter if you ride an Eunorau hub-motor ebike with an M12 rear axle and need to mount an M10 trailer without altering the dropout.