Since you mention brake "bolt" I assume you have a rear caliper brake. If that is the case, then there are options as mentioned above. If you have cantilever brakes (i.e. "bolts"), then Old Man Mountain makes racks designed to attach to those mounts.

http://www.oldmanmountain.com/Pages/...RearRacks.html

I have a few of their racks and they have stood the test of time. I have one mounted on a Langster fixed gear to the seat stays with rubber coated p-clamps they supply. I have had it on there for years and it has been bombproof.