Is there any mount that can attach a Varia RTL510 radar to a Bontrager rack? I have that rack on my hybrid bike so I can't mount the radar on the seatpost because the cargo basket gets in the way. There are several mounting holes on the rear of the rack so it should be possible, but I haven't seen anything that looks like it would fit.
Did you look at the link? It is saddle mount that can be fitted to the rear of a rear rack
Buy a flat bottomed stem mount and fix it to the rack. I can’t take credit for the idea but check the link for some photos to give you an idea.
I have a Bontrager rack on my Trek hybrid. I ordered a mount from Shapeways. It is 3D printed. In my case I ordered the Dual Varia GoPro rear rack mount.
I could not find a flat bottomed stem mount mentioned by one of the posters below, but just bought a cone shaped stem mount and with a few washers and bolts have it mounted tightly to the back of my rack. I check it regularly to make sure all is tight and strong, but it has been very good for hundreds of miles so far.
I just randomly picked one on Amazon for about $10
