This is intended for mounting on the midway point of forks that have a rack mounting braze-on on them. It is intended for use with a standard M5 4mm allen head bolt. You may need to slightly enlarge the bolt hole. Future refinements for this design will include a larger countersunk hole to accomodate a washer, a larger bolt hole diameter to eliminate the need to slightly expand the hole, and a counter sunk relief for a washer to go between the base and the fork.