caliper bolts

waterford123 Posts: 172
edited February 2013 in Workshop
Bit of a long shot, but does anyone know what length caliper bolts i would need for 105 brakes ( bolts for the pivot nuts) to go on a Trek E11 frame? I bought the frame from a club mate. He's got no idea but 13mm is way short. I would like to order some if anyone can help?