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Old 10-10-08, 06:10 PM   #1
ginsoakedboy
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Canti's for closely-spaced bosses on older bike

OK - I'm cross-posting with the same issue on C&V, but I'm desparate and need max exposure to try to find a resolution.

I have a 1984 Raleigh Portage touring bike that I've been working to restore. I'm down to the last part I need. The canti bosses are about 60-61mm apart, c-to-c, which is too close for any modern canti.

To add to the difficulty, the bosses are sort of the reverse of normal, in that the 3 anchor holes to anchor the return spring are to the outside instead of toward the inside of the fork blade.

I think the original brakes were Shimano XT.

Anyone know of anything I can find to work -- or better yet, anyone actually have anything they can help me out with?
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Old 10-10-08, 07:39 PM   #2
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I have been down this road and maybe can help some.

But first, are you switching from 27" to 700" wheels?

If not, then you will have a lot of options. If yes, then it gets dicier.

jim
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Old 10-12-08, 12:26 AM   #3
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Originally Posted by jgedwa View Post
I have been down this road and maybe can help some.

But first, are you switching from 27" to 700" wheels?

If not, then you will have a lot of options. If yes, then it gets dicier.

jim

No - no change to the wheel size. In fact, the rims are still the originals that came with the bike. The issue, as I understand it, is that the canti bosses on some of the bikes built in that era were spaced about 6 cm, whereas the current standard is about 8cm. So in trying to use modern brakes, there isn't enough clearance.
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Old 10-12-08, 06:32 AM   #4
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Okay, you will not have a ton of trouble finding what you need then.

One difference between older and newer cantis is the degree to which the arms are splayed out from the pivot. Remember old Deore ones that are shaped like a triangle? One angle at the boss pivot. One angle at the pad. And then, one angle pretty far outboard where the straddle wire is secured. The distance between the last two angles might be about two inches. The equivalent distance on a modern canti might be about an inch or so. If you (or a buddy, or a patient LBS) has a box of old brake parts, root through it to find a set with canti arms that stick way out to the side.

Not all such brakes have that triangle shape. Some simply have a radical dog-leg bend to them to get the straddle wire attachment point far outboard of the boss. There is nothing at all wrong with such brakes. MTBers moved away from them simply for aesthetic reasons because they stick out so far (they call them bush-cutters as I recall). But you need them.

I take it the bike does not have the original brakes on it now? If it did, use what it came with. Decent old canti brakes work great. New pads help tremendously. And be sure to get the get the angle of the straddle wire correct. And be sure you are using canti levers, not v-brake levers (they pull different amount of cable).

And, it might help to buy a little more room in there by putting all the toe-in adjustment washers on the outside. And, there are even low-profile pads that will buy you a bit mroe. But these things should not be necessary with the right brakes.

jim
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Old 10-12-08, 06:43 AM   #5
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Oh yeah, I forgot about the issue of the spring holes being in the wrong place. Damn, this one might be harder.

Again, can you use the original brakes that were made to be used with this *******-technology beast (I say that lovingly; I am a C & V person)? Obviously, they will be made to order for the combination of variables you have. If you are shunning them because they do not work well, then put new pads on there, and set them up right, and run.

Could you figure out what brakes came on it, and seek out (Ebay?) a set?

Someone on here had this problem a few weeks ago. Several people suggested that they had drilled new holes in the right place to use the brakes they wanted. Not sure I recommend that, but I have never done it. Anyway, seems like there would not be any material over there on the wrong side to drill into.

Lastly, there was a fashion for a brief time for not having the spring seat on the frame at all. Instead the spring seated in a little collar that was part of the arm itself. When the arm was tightened down on the boss, this collar was kept in place by friction. As such, with such an arm it would not matter where the holes where. I have an NOS set of such brakes that I have been sitting on waiting for just such a use. But, they do not have the splay you may need to compensate for narrow bosses.

One last thought. I have never tried it, but you could you simply switch out the springs from the left to right? Would that also reverse which side of the boss the spring seated while keeping the direction of the tension the same? I am not smart enough to think this through reliably. Anyone else?

jim
(edit: that word got bleeped? Wow, BF is set for a bunch of *******s.)
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Old 10-12-08, 07:19 AM   #6
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I encountered the same problem with a Raleigh Technium mountain bike that belonged to my daughter. This was never a high dollar bike and I wasn't concerned with keeping it "original". I never did find a set of suitable brakes although I didn't really persue the vintage sources.

Eventually I converted the bike to 700c wheels and a standard reach road caliper fit the hole in the fork crown perfectly. I assume the rear seat stay bridge would have worked also but, since I converted the bike to fixed gear, I didn't install a rear brake.
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