Cantilever brakes

[campagman]

I have just been fitting some replacement forks to my work bike (road). The new forks have braze ons for cantilever brakes which I thought would be ok as I have some old cantis from an old MTB. All was going well until I went to fit the brakes, I have a problem.
When I slide the brake onto the stud there is not enough room for the brake and block next to the wheel. I can slide the brake on but can see that I will not be able to adjust the block to contact the rim correctly. The blocks are quite thick and have a threaded post to mount onto the brake. There are also no spherical washers to adjust the pad.
The set-up looks so wrong that I thought that MTB cantis and Road cantis must be different but I have done a quick search and I don't think so.
Any help or recommendations will be greatly appreciated.

 

[MartinC]

I've seen this problem before. I had an old Raleigh Tourer where the forks were narrow and the distance between the brake bosses wasn't compatible with modern cantis. They were alright with old high profile cantis where the blocks were on unthreaded posts and could be adjusted to fit. I couldn't upgrade to newer brakes because they came with threaded posts which didn't allow enough adjustment. If you can find the technical data for the brakes it may specify what the min and max distance between the bosses may be. This may be more use in checking alternative brakes though - it looks like the current ones don't fit.

 

[campagman]

I had another look at this on Sun when I noticed that the lack of adjustment of the blocks is the main problem. I acquired the brakes from a friend so do not have any info. but I do know that they are old. I measured the distance between brake mounting bosses on the forks as approx. 53 mm between ctrs, I don't know if this is narrow or about normal?
I managed to do a very Heath Robinson bodge by filing the blocks at an angle so that they are approx. parallel to the rims. I remember asking myself at the time should I really be doing such a bodge with my brakes? I tried them out around the block and they seemed to stop ok. I used the bike to work today and have got home ok. The brakes were ok but will be a lot better when the blocks bed in to the rims better. This is not a permanent fix and i will get some new/better cantis when I get chance.

 

[andrew_s]

For comparison...
Raleigh Randonneur tourer, cantilever boss spacing: 64mm F, 73mm R
26" wheel expedition-type tourer, V-brake boss spacing 90mm F, ~88mm R

So, I'd call 53mm narrow.

 

[mickle]

Cantilever/ Linear-pull bosses are supposed to be preecisely 3 imperial inches apart (center to center). If they aint preecisely 3 imperial inches apart center to (center) return them forwith to whence they came.