Originally Posted by
HillRider
I do see one potential problem with having a very close clearance between the brake bridge and tire tread and that the possibility of mud buildup locking the rear wheel. .....
If the OP has a very small gap, it could easily be bridged by mud or a small twig and bring proceedings to a sudden halt.
I can assure you that this won't be an issue. My track bike has zero clearance between the bottom of the front brake arch and tire. It's so small that the bottom of the arch can double as a tire saver. Mud can't build up and nothing has ever gotten caught. Every once in a while the tire will pick up a small stone which I hear get ejected with a sharp ping.
If you've ever driven a car in mud or snow and slush, the wheel wells get filled up to where you'd expect issues, but the moving tire always keeps a working gap clear. On bumps the wheel moves up carves out more clearance as needed.
BTW- I've seen some ultra-short wheelbase bikes with zero rear wheel/seat tube clearance and haven't ever heard of issues.
The only barrier to filing the bottom of the bridge for a few millimeters is the risk of weakening it's structure, and that depends on how much material it can spare and how much the OP takes away.