Trailer hitch adapter for bicycles

When I just bought the cheapest bike trailer available, it came with a hitch adapter for the seat post that was at least an order of magnitude too small for ALL of my bikes.

As I ocassionally need to lower the seats for transport on a bike rack, I wanted the hitch on the frame, rather than the seat post anyways.

This model is designed for 37.5mm tube diameter. The print being done in black PETG with 2mm walls and 30% cubic infill made it stiff enough, that it clamps very securely around the frame tube. The interface for the trailer hitch adapter is just in the right place for about 10° of freedom in both directions, if you need more you can modify it with a narrowing or a chamfer in the back.

As I just installed it, this is UNTESTED. Use at your own risk. I will report any updates in a few weeks when I got a bit of use out of it.

The adapter is designed for M6 hardware, screw length needs to be at least 20mm. There is clearence for DIN 912 and DIN 7280 screws.