Trying to find a new 27" fork with canti posts
05-14-18, 08:17 AM
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Trying to find a new 27" fork with canti posts
Been rebuilding a 1984 Univega Gran Turismo touring bike. Everything has gone well so far, except for the front brakes, which I've been fighting with for months now.
As far as I can tell, the position of the canti posts were dictated by the brakes used by the manufacturer, rather than adhering to any sort of dimensional standard. Given the age of the bike and when canti brakes started being used, I can kind of understand it. The original brakes were too crusty to reuse...quite literally. Something was really eating up the alloy, and didn't feel comfortable reusing them. They hold the pads fairly low, and the pads are held on the side of the brake opposite from the post, ie. well away from the fork.
So far, I've tried canti brakes of all sorts, about 8 different sets and about 8 different sets of pads, trying to find a combination that worked. Most of them hold the pads too high, and you can't get them to contact the rim squarely. Also, If the pads are too thick and/or too long, and interfere with the fork blade itself...this pretty much means all of them so far. There's nothing unusual about the new brakes and pads, they're just in the wrong position because of the posts.
The closest I've come to a solution is with Tektro mini-V brakes, and either Kool Stop thinline MTB pads (thin enough to fit between the rim and the fork) or else some generic 50mm-long pads that taper down to the ends, not sure where I got them. Being a fat bastard, braking is important to me, so I'm not keen on using the latter, even though they actually fit reasonably well. The thinline pads, I can't get adjusted to squarely contact the rim...the rear end of the pad toes in pretty severely once I tighten down the nut, even if I shim it out about 5mm with a screwdriver shaft before I tighten down.
So, if I can't find a decent name-brand pad that's roughly the same dimensions as the generic pads, I'm kind of screwed, unless of course I settled for the generics. Also, I worry that even if I do find some pads the right size, it still might not work.
So, I'm almost to the point of replacing the fork itself. Trouble is, nobody seems to make a 27" fork with canti posts. So, as far as the fork goes, I have a few options...have a shop braze on new posts where they should be mounted (though I'm not convinced that would solve the interference issue), get a new 27" fork and have a shop braze on new posts, or get a 700c fork with posts.
Of the three options, I like the third one the best...there's a huge variety of 700c forks available. Two problems I can see, however, are...will the 27" wheels clear the crown of a 700c fork and/or allow enough room for a fender, and is using a 700c fork on a 27" frame going to hose up the steering geometry? I suppose I could put 700c wheels on the bike, but I've already replaced the original wheels with new 27" wheels, so I'm kind of committed.
Given all this, what would you guys do?
As far as I can tell, the position of the canti posts were dictated by the brakes used by the manufacturer, rather than adhering to any sort of dimensional standard. Given the age of the bike and when canti brakes started being used, I can kind of understand it. The original brakes were too crusty to reuse...quite literally. Something was really eating up the alloy, and didn't feel comfortable reusing them. They hold the pads fairly low, and the pads are held on the side of the brake opposite from the post, ie. well away from the fork.
So far, I've tried canti brakes of all sorts, about 8 different sets and about 8 different sets of pads, trying to find a combination that worked. Most of them hold the pads too high, and you can't get them to contact the rim squarely. Also, If the pads are too thick and/or too long, and interfere with the fork blade itself...this pretty much means all of them so far. There's nothing unusual about the new brakes and pads, they're just in the wrong position because of the posts.
The closest I've come to a solution is with Tektro mini-V brakes, and either Kool Stop thinline MTB pads (thin enough to fit between the rim and the fork) or else some generic 50mm-long pads that taper down to the ends, not sure where I got them. Being a fat bastard, braking is important to me, so I'm not keen on using the latter, even though they actually fit reasonably well. The thinline pads, I can't get adjusted to squarely contact the rim...the rear end of the pad toes in pretty severely once I tighten down the nut, even if I shim it out about 5mm with a screwdriver shaft before I tighten down.
So, if I can't find a decent name-brand pad that's roughly the same dimensions as the generic pads, I'm kind of screwed, unless of course I settled for the generics. Also, I worry that even if I do find some pads the right size, it still might not work.
So, I'm almost to the point of replacing the fork itself. Trouble is, nobody seems to make a 27" fork with canti posts. So, as far as the fork goes, I have a few options...have a shop braze on new posts where they should be mounted (though I'm not convinced that would solve the interference issue), get a new 27" fork and have a shop braze on new posts, or get a 700c fork with posts.
Of the three options, I like the third one the best...there's a huge variety of 700c forks available. Two problems I can see, however, are...will the 27" wheels clear the crown of a 700c fork and/or allow enough room for a fender, and is using a 700c fork on a 27" frame going to hose up the steering geometry? I suppose I could put 700c wheels on the bike, but I've already replaced the original wheels with new 27" wheels, so I'm kind of committed.
Given all this, what would you guys do?
05-14-18, 08:35 AM
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Have you tried only new cantilevers? That could be the problem. The canti posts are narrower on older bikes and that can interfere with new cantilevers that were designed for bikes with the posts farther apart. I know that was a real problem with my 1983 Trek 720. I even had this problem with my 1993 Bridgestone XO 2 which can take a pretty fat tire but the posts are not quite as wide as newer bikes.
I'd look around for some quality used vintage cantilevers.
I'd look around for some quality used vintage cantilevers.
05-14-18, 09:23 AM
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Maybe post a photo of the old crusty cantilevers, someone might have a good pair of those.
The original rim width may have been much narrower than what you now using(?). That affects the geometry too.
The original rim width may have been much narrower than what you now using(?). That affects the geometry too.
05-14-18, 12:29 PM
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Been rebuilding a 1984 Univega Gran Turismo touring bike. Everything has gone well so far, except for the front brakes, which I've been fighting with for months now.
As far as I can tell, the position of the canti posts were dictated by the brakes used by the manufacturer, rather than adhering to any sort of dimensional standard. Given the age of the bike and when canti brakes started being used, I can kind of understand it. The original brakes were too crusty to reuse...quite literally. Something was really eating up the alloy, and didn't feel comfortable reusing them. They hold the pads fairly low, and the pads are held on the side of the brake opposite from the post, ie. well away from the fork.
So far, I've tried canti brakes of all sorts, about 8 different sets and about 8 different sets of pads, trying to find a combination that worked. Most of them hold the pads too high, and you can't get them to contact the rim squarely. Also, If the pads are too thick and/or too long, and interfere with the fork blade itself...this pretty much means all of them so far. There's nothing unusual about the new brakes and pads, they're just in the wrong position because of the posts.
The closest I've come to a solution is with Tektro mini-V brakes, and either Kool Stop thinline MTB pads (thin enough to fit between the rim and the fork) or else some generic 50mm-long pads that taper down to the ends, not sure where I got them. Being a fat bastard, braking is important to me, so I'm not keen on using the latter, even though they actually fit reasonably well. The thinline pads, I can't get adjusted to squarely contact the rim...the rear end of the pad toes in pretty severely once I tighten down the nut, even if I shim it out about 5mm with a screwdriver shaft before I tighten down.
So, if I can't find a decent name-brand pad that's roughly the same dimensions as the generic pads, I'm kind of screwed, unless of course I settled for the generics. Also, I worry that even if I do find some pads the right size, it still might not work.
So, I'm almost to the point of replacing the fork itself. Trouble is, nobody seems to make a 27" fork with canti posts. So, as far as the fork goes, I have a few options...have a shop braze on new posts where they should be mounted (though I'm not convinced that would solve the interference issue), get a new 27" fork and have a shop braze on new posts, or get a 700c fork with posts.
Of the three options, I like the third one the best...there's a huge variety of 700c forks available. Two problems I can see, however, are...will the 27" wheels clear the crown of a 700c fork and/or allow enough room for a fender, and is using a 700c fork on a 27" frame going to hose up the steering geometry? I suppose I could put 700c wheels on the bike, but I've already replaced the original wheels with new 27" wheels, so I'm kind of committed.
Given all this, what would you guys do?
As far as I can tell, the position of the canti posts were dictated by the brakes used by the manufacturer, rather than adhering to any sort of dimensional standard. Given the age of the bike and when canti brakes started being used, I can kind of understand it. The original brakes were too crusty to reuse...quite literally. Something was really eating up the alloy, and didn't feel comfortable reusing them. They hold the pads fairly low, and the pads are held on the side of the brake opposite from the post, ie. well away from the fork.
So far, I've tried canti brakes of all sorts, about 8 different sets and about 8 different sets of pads, trying to find a combination that worked. Most of them hold the pads too high, and you can't get them to contact the rim squarely. Also, If the pads are too thick and/or too long, and interfere with the fork blade itself...this pretty much means all of them so far. There's nothing unusual about the new brakes and pads, they're just in the wrong position because of the posts.
The closest I've come to a solution is with Tektro mini-V brakes, and either Kool Stop thinline MTB pads (thin enough to fit between the rim and the fork) or else some generic 50mm-long pads that taper down to the ends, not sure where I got them. Being a fat bastard, braking is important to me, so I'm not keen on using the latter, even though they actually fit reasonably well. The thinline pads, I can't get adjusted to squarely contact the rim...the rear end of the pad toes in pretty severely once I tighten down the nut, even if I shim it out about 5mm with a screwdriver shaft before I tighten down.
So, if I can't find a decent name-brand pad that's roughly the same dimensions as the generic pads, I'm kind of screwed, unless of course I settled for the generics. Also, I worry that even if I do find some pads the right size, it still might not work.
So, I'm almost to the point of replacing the fork itself. Trouble is, nobody seems to make a 27" fork with canti posts. So, as far as the fork goes, I have a few options...have a shop braze on new posts where they should be mounted (though I'm not convinced that would solve the interference issue), get a new 27" fork and have a shop braze on new posts, or get a 700c fork with posts.
Of the three options, I like the third one the best...there's a huge variety of 700c forks available. Two problems I can see, however, are...will the 27" wheels clear the crown of a 700c fork and/or allow enough room for a fender, and is using a 700c fork on a 27" frame going to hose up the steering geometry? I suppose I could put 700c wheels on the bike, but I've already replaced the original wheels with new 27" wheels, so I'm kind of committed.
Given all this, what would you guys do?
I went through a similar situation with my 86 Passage recently. The canti posts were so close together that changing anything from the original setup caused all kinds of headaches. I ended up letting gugie do some modifications to make life easier.
Anyway, look for a set of Deore LX canti brakes with the original front and rear specific pad holders. The pad holders did not hit the inside of the forks or seatstays when I tried them. I did not end up using the original pad holders as the area that contacts the rim was to vertically tall for the rims I used, instead I am using Kool Stop Cross holders and pads. They are not so long as to hit the fork or frame either and fit the brake track width on my rims better.
I can take measurements and pics after work if you need, just let me know. Hope some of that that helps.
05-14-18, 10:11 PM
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Anyway, look for a set of Deore LX canti brakes with the original front and rear specific pad holders. The pad holders did not hit the inside of the forks or seatstays when I tried them. I did not end up using the original pad holders as the area that contacts the rim was to vertically tall for the rims I used, instead I am using Kool Stop Cross holders and pads. They are not so long as to hit the fork or frame either and fit the brake track width on my rims better.
I can take measurements and pics after work if you need, just let me know. Hope some of that that helps.
I can take measurements and pics after work if you need, just let me know. Hope some of that that helps.
05-15-18, 08:07 AM
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I know of what brakes you speak, as I had the same issue when I wanted to fit some mini-v brakes to my Gran Turismo. I had to go back to the stock Dia-Compe brakes, good thing they work just fine 
I believe I have a spare set, I can take a look if you want to go with the stock config.
I believe I have a spare set, I can take a look if you want to go with the stock config.
05-15-18, 08:46 AM
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Canti post spacing can result in some problems. There was no standard- my 84 Voyageur SP is 50mm between the bosses on the fork. I have to deflate a 27 x 1 1/4" Pasela to take the wheel out- I'm using 1992-ish Suntour XC Pro brakes on there. I'll probably be putting the stock Dia Compe 981s back on- just because they're cool.
I think a lot of people look at the Tektro 720 and think it looks like a typical classic triangular cantilever brake and think it's the same. They're just not made to work with the posts so close together, despite them looking like the BR-MC70/M730/M732/MT-60 brakes...
I think a lot of people look at the Tektro 720 and think it looks like a typical classic triangular cantilever brake and think it's the same. They're just not made to work with the posts so close together, despite them looking like the BR-MC70/M730/M732/MT-60 brakes...
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