Having just spent the whole afternoon swearing at these, I thought I’d post my recipe.
The bike: 2007 era Planet-X Kaffenback with carbon forks (with lugs for mudguards), and tektro mini-V brakes
Front problem: the metal hanger thing attached to the mudguard is too short for the fork. When bolted to the fork crown, the guard is far from the tyre, and interferes with the brake.
Front solution: saw off the bit of the guard in front of the fork. Attach using hanger to back of fork.
Rear problem: no “normal” hole for calliper brakes on the frame, so nothing for hanger to attach to.
Rear solution: drill a hole in the mudguard so it can be bolted directly into the threaded hole in the seat stay wishbone. But wait! You need to put some spacers between the guard itself and the wishbone so that it doesn’t get in the way of the rear brake. I used four bits of old inner-tube.