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Just bought an old retro road frame, the calipers that came with it were dual pivot shimano jobs from the early 90s and totally goosed. So I picked a a pair of duraace 7700 from eBay, they look like bike jewelry
unfortunately it transpires that the rear won’t quite clear the rear tyre, it’s literally 2 - 3 mm too short, so looking for a solution. i don’t really want to buy a long drop caliper given the ones I have are lovely.
option 1- file the pads, not sure this is the best idea
option 2 - take a dremel to the caliper so I can move the pad 2-3 mm further down. It’ll still be a bit tight if I do that however
option 3 - use an offset brake pad holder. Cheap but not sure they are safe! Like these
option 4 - use a brake caliper drop bolt. I only need about 5mm extra clearance however, whereas the one I’ve seen drops the mounting bolt by 2.5 cm so may be too much. Any other products do similar. Ideally I’d make my own, but don’t have the means to do so
any other options available?
Option 5: Restore the correct brakes.
They are race callipers and need tight clearance - you must have a fair old drop as my DA and 600 have the pads in the middle of the slot. You could carefully Dremel out the slot 2-3mm, but I wouldn't do more. The dual pivots are possibly long drop, especially if there is guard clearance. There isn't clearance on DA callipers for guards. Any way of 'saving' the dual pivots (disassemble and clean up).
The old calipers could probably be restored but are frankly cheap and nasty looking things, where as the DA ones look like pieces of fine art
Now granted I’d rather have functioning brakes than nice looking ones when I’m descending a hill at 30mph, but since this is a wee retro build of a bike I always wanted as a kid, and it isn’t really going to be ridden very much or very hard, how it looks when hanging on the wall is quite important!
A picture might help!
A couple of thoughts:
- can you double check whether the rear is 27" or 700c (similar but not identical diameter)
- what tyre are you using? My bikes of that era are/ were designed for narrow rim width and 21 or 23 mm max tyres.
- you can get a small bracket like this one Brake Extender for Brompton Folding Bike (EE G4 brake) - AliExpress