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Cantilever boss spacing

Mark Silver2020-07-21 11:46:40

Anyone care to speculate as to why on a couple of class 1970-80’s tandems of mine, the cantilever bosses are so much more close together  at the front compared to the rear?

Two different machines (an Oliver and a Swallow), share the same spacing of 50mm centres on the front forks and 80mm on the rear seat stays.  In modern times, this is a nuisance, as upgrading away from the original Mafacs to a V-brake is easy at the rear, but cannot be done at the front. 

On the Swallow I’ve done the conversion, and now the front is the same as the rear and it all works well, but still can’t see why Tony Oliver and Pete Bird made it like that in the first place.

What am I missing?

Steve Upson2020-07-22 11:24:26

On my 70's Roberts tandem I use Shimano XT V brakes with Coolstop Thinline brake blocks. The toe in washers need to be discarded because of lack of space on the front forks.. This works well provided that Chas (or Pete or Tony) have brazed the bosses in the right place! You will also need to use brake levers designed for V brakes to give the extra cable pull. I use Cane Creek but other makes are available. The end result is a worthwhile improvement in braking performance.