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Old 11-28-06, 10:43 PM   #1
peripatetic
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several cantilever ponderings (NOT V-brakes)

I just tried hooking up some Tektro BMX levers to the older Dia-Compe canti brakes on an 80s road bike. The levers weren't working. I've gone and done a search and read up on this stuff, but I couldn't figure out exactly what the problem is.

Are the BMX levers made for only direct-pull brakes? (I know nothing about BMX bikes right now--last one I had was my chrome Mongoose back in 5th grade). If so, what levers for an upright bar would I look for to use with these brakes?

Also, can newer link wires be used with older canti brakes? How does one determine the proper length for link wires?

Do transverse cables (for cantis and older centerpulls) stretch like regular brake cables, and should they be replaced? Do they produce stainless steel versions?

Finally, am I correct in understanding that the original canti brake design was flawed because of this (from Sheldon Brown):

" Unfortunately, conventional center-pull cantilevers prouduce exactly the opposite variation! As the lever is pulled, the yoke angle gets sharper and sharper, while, in the case of a low-profile model, the pivot-cable distance decreases. Both of these conditions reduce the mechanical advantage as the brake is applied.

Since the travel increases as the brake shoes wear down, braking performance degrades as the shoes wear, not because the shoes have any less grip, but because the mechanical advantage has decreased."

Is this what gave rise to the V brake design?

Thanks.
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Old 11-28-06, 11:06 PM   #2
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If possible, Take a pic of how you rigged this up. Cantilever cables need to pull upwards on the yoke, then the yoke pulls an upside-down U shaped cable that sits between the two cantilever brake arms, pulling them together.

This is how cantis should look. The thing in the top middle is the yoke.

http://www.interlocracing.com/brakecafam_straighton.gif

http://www.cambriabike.com/Images/pr...ring_cants.jpg
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Old 11-28-06, 11:14 PM   #3
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Hi, thanks for the response. I think I was a bit unclear. I hooked the cable and yoke up fine: the problem was that I ended up with too much mechanical advantage. I.e., the levers bottomed out against the bars with insufficient pull on the actual canti arms. The cantis I'm using are 80s dia-compes with a transverse cable and traditional yoke (no link wire). They are the original brakes on a Centurion Elite GS touring frame.
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Old 11-28-06, 11:29 PM   #4
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Thanks for that, I've often wondered what cantilever brakes were.

Richard
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Old 11-28-06, 11:47 PM   #5
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How much clearance do you have between the rim and the pads? I have probably 2 penny widths on each side of my canti-equipped Outlook. It would be less than that, but I had to give myself enough room to squeeze them together to unhook the QR cable (I have QR wheels front and back on it, which I often swap on a whim)

If it weren't for me swapping rims, the clearance would be even tighter. The wheels are almost perfectly true, so I could have the brakes pretty close to the rim.

is it possible to get them a bit closer to the rim without dragging?
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Old 11-29-06, 02:22 AM   #6
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the pads on my mountain bike are about 1 peeny away from the rim at most. if your wheel is true then get them as close as you can...
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Old 11-29-06, 06:04 AM   #7
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Lots of vairables with cantis. Could you post a scan?
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Old 11-30-06, 11:26 PM   #8
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I can post a pic, but not till I can get back to the bike (stored at a friend's place). But just so I'm clear, are normal BMX brakes supposed to work with normal cantis?
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Old 11-30-06, 11:34 PM   #9
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Quote:
Originally Posted by peripatetic
I can post a pic, but not till I can get back to the bike (stored at a friend's place). But just so I'm clear, are normal BMX brakes supposed to work with normal cantis?
There are different kinds of BMX brakes. I've seen linear pull brakes ( v-brakes) as well as sidepull brakes (more like oversized road calipers) on BMX bikes. I'm certainly no expert on BMX brakes, but I suspect you were using brake levers designed for linear pull brakes, which aren't compatible with traditional canti's. I assume since you're using BMX levers, you're using some type of upright handlebar (in other words, not drop bars). In this case, brake levers from an older mountain bike equipped with cantilever brakes would be your best bet-
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Old 12-01-06, 04:44 PM   #10
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Originally Posted by well biked
There are different kinds of BMX brakes. I've seen linear pull brakes ( v-brakes) as well as sidepull brakes (more like oversized road calipers) on BMX bikes. I'm certainly no expert on BMX brakes, but I suspect you were using brake levers designed for linear pull brakes, which aren't compatible with traditional canti's. I assume since you're using BMX levers, you're using some type of upright handlebar (in other words, not drop bars). In this case, brake levers from an older mountain bike equipped with cantilever brakes would be your best bet-
Yeah, thanks. You're right, I was using these newer Tektro levers for upright handlebars--was originally planning to use them with normal sidepull calipers. I figured that since these cantis took normal road levers for upright bars, they'd also take BMX levers for a flat bar that worked on normal sidepulls. But they most certainly are not working. I'm going to try and find some decent, older MTB brakes now (any suggestions?)

Thanks again for the input.
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Old 12-01-06, 05:15 PM   #11
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Sidepull, cantilever, and u-brakes (which some bmx have) I believe would all use the same type of lever, a short-pull lever as opposed to long-pull which is for v-brakes (unless I'm thinking backwards). But whatever kind of lever it is it shouldn't bottom out. I think a long-pull lever would just be a lot harder to apply pressure to.

It sounds like there's something messed up with the setup because I think bmx levers should work just fine on cantilevers.
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Old 12-01-06, 07:17 PM   #12
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It sounds like there's something messed up with the setup because I think bmx levers should work just fine on cantilevers.
Again, it depends on which type of brake the BMX bike has on it. If it has linear pull brakes, the levers won't work well at all with traditional cantilever brakes. If it has sidepull calipers or u-brakes, the levers should work fine-
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Old 12-01-06, 10:51 PM   #13
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[QUOTE=peripatetic] I'm going to try and find some decent, older MTB brakes now (any suggestions?)

QUOTE]

Levers or caliper/arms?
I've got buckets of both laying around. tell me what you need.
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