27" -> 700c Brake Reach Issue...
02-16-19, 06:57 PM
#1
Senior Member
Thread Starter
27" -> 700c Brake Reach Issue...
I know there isn't Much difference between the sizes, but the bike in question just isn't working out. It's a Bridgestone T700 that originally had 27" wheels. I put 700c on it and the rear just won't fit any of the brakes that I've tried. The pad won't go down far enough to hit only the rim. The posts are too high up. Any ideas? Are there any particular, preferably common, cantilever brakes that are known to have pads closer to the post mounts?
02-16-19, 07:01 PM
#2
working on my sandal tan
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There are offset pad holders that might help. One example: https://www.bdopcycling.com/BDop%20Offset%20Holders.asp
02-16-19, 07:25 PM
#3
Senior Member
I know there isn't Much difference between the sizes, but the bike in question just isn't working out. It's a Bridgestone T700 that originally had 27" wheels. I put 700c on it and the rear just won't fit any of the brakes that I've tried. The pad won't go down far enough to hit only the rim. The posts are too high up. Any ideas? Are there any particular, preferably common, cantilever brakes that are known to have pads closer to the post mounts?
Yeah, 4mm difference, but this can on occasion be a PITA. You'll probably have to use vintage cantilevers, as you likely already know. I'd try to find some Dia/Gran Compe GC960. They use post type pads. This means you can adjust them pretty far in - more post on the inside, and that will effectively lower the position. The caliper arms themselves will go out more than normal, but as they are semi low profile it should be OK. IIRC they use double barrel straddle wires. You can make your own if you can't find them. There were several other similar brakes made by Dia Compe. Should be easy enough to find.
Many of the touring bikes of that era had sort of an intermediate canti post position, and could be adjusted for either size. I just looked at some pics of mid 80s T700's though, and they do indeed look to be pretty high. Worse case, you can always go back to 27".
Last edited by Salamandrine; 02-16-19 at 07:29 PM.
02-16-19, 09:33 PM
#4
señor miembro
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Probably won't help you with cantilevers, but I've had to get out my dremel tool and lower the caliper pad slot on two of my 700c conversions. Usually, it's only the rear that's the problem. For my '60 Paramount, it was both front and rear.
02-17-19, 11:56 AM
#5
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@salamandarine is correct, the older, period correct DC 960 or 981/982/983. Heck, even a 988 which looks very similar to some newer Shimano canti models. The necessary features a 1) post-mount style 2) the post mount is a fully pivoting design that allows for toe-in and for rim height and 'angle of attack' adjustment. I've used 960s (or was it 983s?) on an '82 Miyata 1000 that I ran 700C wheels on (27" originally). Very narrow canti post spacing, but I got it to work easily.
This reminds me, I gotta get another 1000.
This reminds me, I gotta get another 1000.
