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Old 01-19-14, 10:01 AM   #1
zacster
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Changing canti brake cable geometry

I've installed a dynamo light onto the fork crown brake bolt, on a bike that has canti brakes, and the light mount and the canti triangle yoke get in the way of each other. These are old style 1990 cantis with a full traverse cable, not the slightly newer ones where the main cable runs all the way to one side.

If I move the yoke down towards the wheel, and then shorten the traverse cable to compensate, will I severely impact the braking performance? I tried reading the Sheldon Brown article but I couldn't make sense of it as it gets very technical and goes through all the variations. Am I increasing mechanical advantage or decreasing it? Is increased mechanical advantage a good thing or a bad thing? (I think it goes opposite of what you'd think.)

I've already removed the fender as that left no room for manipulating the cable. It was cracked anyway. I've taken the bike in the rain maybe 5 times in the 2 years I've had them on. I'll just avoid the rain.

I also need to replace the main cable as it is frayed at the yoke from being adjusted all these years before I ended up with this bike, although the housing looks to be relatively new.
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Old 01-19-14, 10:11 AM   #2
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Altering brake function to accommodate the mounting of a light does not make much sense. Try relocating the light.
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Old 01-19-14, 10:22 AM   #3
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You a Math Major, ? it may matter in the calculations.. [sheldon's wife taught college math]


Quote:
These are old style 1990 cantis with a full traverse cable, not the slightly newer ones
If you need a low crossover cable , the compact type cantilever is better, you might benefit from changing the calipers
from the L style like Pauls 'touring' instead of 'neo retro'..

http://www.tektro-usa.com/category.p...d=185&subcat=0

http://www.trpbrakes.com/category.ph...d=185&subcat=0 velo orange has the polished version ..

http://www.sram.com/avid/products/shorty-4-rim-brake

these types function better in situations with low clearance, than shorter thwart cables on the Long L type.

I had a set of That sort on my loaded touring bike .. low profile .. cable passes under the rack mounts ..

so consider different brakes ..

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I've installed a dynamo light onto the fork crown brake bolt, on a bike that has canti brakes, and the light mount and the canti triangle yoke get in the way of each other.
or, simpler, run the transverse. cable a lot longer, up and over , light mount under it.

Last edited by fietsbob; 01-19-14 at 10:34 AM.
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Old 01-19-14, 11:03 AM   #4
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I found this image that might help visualize things. But i do have a question for the OP. Does the light bracket allow the primary cable to travel past it/through it? The common light brackets that mount to the fork crown usually act as a block for the primary cable and the straddle cable then needs to be above the bracket. What am I missing? Andy.
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Old 01-19-14, 11:06 AM   #5
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"run the transverse. cable a lot longer, up and over , light mount under it."

This will also prevent the straddle cable from catching in the tire and putting the brake "on" hard if the main brake cable should break or come loose. If I do not have such a fitting (or a fender) under my wire I put a small bracket there for this exact reason.
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Old 01-19-14, 03:01 PM   #6
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Here's a picture. You can see the cable go through the mount and where the yoke ended up. Maybe I should just go out and try it.
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Old 01-19-14, 03:21 PM   #7
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Looks like a little lower might be beneficial . I like a 90 degree angle from cable to arm to post mount. You will probable need to re-set pads.
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Old 01-19-14, 03:59 PM   #8
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A lower straddle cable will give better "leverage".
IF your brakes are a bit weak, that could be good.
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Old 01-19-14, 04:10 PM   #9
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Why not convert it to V-brakes? Then the cable will off to the side, the light can stay where it is and you'll have improved braking. Just a thought.
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Old 01-19-14, 04:25 PM   #10
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Originally Posted by Murray Missile View Post
Why not convert it to V-brakes? Then the cable will off to the side, the light can stay where it is and you'll have improved braking. Just a thought.
The problem is converting to V-brakes requires a brake lever change or a Travel Agent. I agree they do work better.
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Old 01-19-14, 04:37 PM   #11
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Here's a picture. You can see the cable go through the mount and where the yoke ended up. Maybe I should just go out and try it.
I was wondering about the possibility of a split bracket. Did you make the changes yet? The set up photoed looks to be real close to working, WRT bracket/straddle clip clearance. While i like the general shape of those cantis I don't like the lack of pad choices and the lack of much pad/arm spacing choices. If it were mine I'd get a set of MT-62s or their cousins. (Which is just about what the diagram i posted are). Andy.
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Old 01-19-14, 04:53 PM   #12
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I'd go ahead and shorten the yoke even more. As a general rule, the shorter the yoke the more leverage. It is possible to get carried away, but you have plenty of room before that happens.
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Old 01-19-14, 05:28 PM   #13
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I just took it on a spin and the brakes work fine the way they are in the picture, so no worries. One of the problems I originally had was the fender, there was no clearance at all with the fender AND the light. I'm going to look for a fender that rides closer to the tire, the one I had was for 27" wheels and I have 26 on this bike. The thing is though the mounting bolt is still in the same place so I'll need a fender mount that can drop down lower.

I'm not looking to change brakes, as you can maybe see this is my clunker/commuter. The dynamo wheel and light is worth a lot more than the bike. V-brakes would require different levers if I understand this correctly. I may look at new pads as these are pretty old.

In the meantime its going to get very cold here, and I don't ride when it is below 32 in the morning. Time to get back on the trainer.

Last edited by zacster; 01-19-14 at 05:31 PM.
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Old 01-19-14, 07:20 PM   #14
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Originally Posted by Murray Missile View Post
Why not convert it to V-brakes? Then the cable will off to the side, the light can stay where it is and you'll have improved braking. Just a thought.
Not necessarily, I have Canti's set up with the right levers that stop and modulate just as good as V's . It's about part selection and setup.
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Old 01-19-14, 07:39 PM   #15
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I just took it on a spin and the brakes work fine the way they are in the picture, so no worries. One of the problems I originally had was the fender, there was no clearance at all with the fender AND the light. I'm going to look for a fender that rides closer to the tire, the one I had was for 27" wheels and I have 26 on this bike. The thing is though the mounting bolt is still in the same place so I'll need a fender mount that can drop down lower.

I'm not looking to change brakes, as you can maybe see this is my clunker/commuter. The dynamo wheel and light is worth a lot more than the bike. V-brakes would require different levers if I understand this correctly. I may look at new pads as these are pretty old.

In the meantime its going to get very cold here, and I don't ride when it is below 32 in the morning. Time to get back on the trainer.
I completely agree with getting a fender that matches the tire's CURVATURE. But I doubt you'll find a fender with an extra tall/long mounting clip, all fenders that I've dealt with assume the "proper" matching of tire and frame. But it is easy to make an extension for the clip. A simple piece of strip the right width and length (and maybe about 1/8" thick if AL) with a couple of holes drilled in it will allow the fender to sit close to the tire and still attach to the fork crown. Andy.
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Old 01-19-14, 08:04 PM   #16
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Not necessarily, I have Canti's set up with the right levers that stop and modulate just as good as V's . It's about part selection and setup.
I was addressing the OP's situation specifically. For the OP inexpensive V brakes would be an improvement over the factory cantis on his TREK and alleviate his cable interference but he doesn't want to replace his brake levers and I can respect that. I too have a set of cantis that work as well as V brakes but I also have a pair of 1997 TREK 820s I converted to V brakes and it was a major improvement on both.
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Old 01-19-14, 09:14 PM   #17
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Back when I first got this bike I thought about replacing the levers/shifters as one side did not work. What was available was compatible with both V-brake and cantis by changing the cable routing I think. But ultimately another BFer offered me a pair of Canti only 7 speed levers and that's what I use. This entire build was done on the cheap, that is until I put together the dynamo wheel and light these last few weeks. These cost more than the bike and everything else I've put onto it combined. Most of the additions were from existing old parts and accessories, and then I got those levers from user ThermionicScott. That's what I've been using.
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Old 01-21-14, 12:38 PM   #18
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The problem is converting to V-brakes requires a brake lever change or a Travel Agent. I agree they do work better.
Last year I upgraded my 1998 RoadMaster’s previous front traditional cantilever brake to an Acera V-Brake, but I continued to use its integrated EF20 7-speed shifter/brake levers which were made for traditional cantilever brakes (short throw brake levers). It works fine however, the new V-Brake requires greater cable adjustment precision when setting up the V-Brake in order to provide enough brake lever usage as well as provide sufficient pad/rim clearance via the released brake lever.

Even while using the shorter brake lever throw, the braking performance of the new V-Brake blows away the old cantilever brake it came with and it has since spared me from a couple of vehicle collisions (“last instant pull outs”) that the old cantilever brake would surly have failed to prevent. Needless to say, I was glad that I had upgraded to the new V-Brake.

And so, I’m pleased with its V-Brake performance even without the use of a Travel Agent.
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Old 01-21-14, 05:50 PM   #19
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Now you have me looking at v-brakes. Braking on this bike, with the old canti's and mismatched shifters/levers, was never great, but I also never had an accident from it. It doesn't appear to be too expensive a proposition either. EF65 7 speed is about $35 for the pair and includes cables and housing, and new v-brakes start at around $15 each and go up for better ones and include pads. I need new pads and cables anyway, and I know how all these little things start to add up.

In the meantime it is snowing out there and too cold to ride through the end of the week at least. I built my front wheel last week, rebuilt my rear with a matching rim yesterday and also installed my light. I doubt I'll get to use them for a while. And anybody that thinks I'm a wimp for not riding in the snow, well have fun. I'd much rather just be back in Hawaii riding up Mt. Haleakala again.
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Old 01-21-14, 06:08 PM   #20
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I think there is a way simpler solution to your problem. There is a special light mount for use with cantilever brakes for around $5 from Peter White Cycles. Here's a pic of it, notice how it is designed to go under the straddle cable.


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Old 01-21-14, 06:32 PM   #21
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I saw that but decided I'd stay with the stock mount to start when I ordered. Now that I have it I see the problem. The suggestion of v-brakes though got me thinking about how these cantis aren't great compared to my Campy Chorus road bike brakes and maybe v-brakes would be an improvement anyway. Plus I have new rims so new brakes + new rims should be a nice ride for the city.

So another question for anybody that knows, are the Avid Single Digit 5 ($20/pair) any good? Or how about the next step up and the SD 7 ($50/pair)? Or should I stick with Shimano? Or Tektro, I have a pair of Tektro road brakes on a bike and they are great. For $55 I could have a whole new brake setup, and new shifters as well. What I have is almost 25 years old at this point and from what I've seen of the newer gear even on cheap bikes is that it works well. I can't say that for my old LX.

And how do you like your Fly light? I have the Cyo and I only have one ride so far, and that was just a quickie to test it.

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Old 01-21-14, 06:59 PM   #22
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And how do you like your Fly light? I have the Cyo and I only have one ride so far, and that was just a quickie to test it.
I got the fly designed for bottle dynos (standlight/no switch). It was only $20 + $5 for the mount. I have to say, for the money it's a great light. I ride recreationally at night on the rail trail, and it's more than enough for that.

As for the brakes, my opinion is that it's all about the pads and the setup. New pads/cables on your current brakes will make a huge difference. If you go with V-brakes, I'm not sure how they'll behave with fenders, don't have any bikes with fenders/v-brakes.
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Old 01-21-14, 08:20 PM   #23
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........ If you go with V-brakes, I'm not sure how they'll behave with fenders, don't have any bikes with fenders/v-brakes.
I have 60mm wide fenders on my hybrid with V-brakes with front suspension fork but, they are fenders for 26 inch wheels on a bike with 700c wheels..... I don't "think" that made any difference in brake clearance though, if anything it may have reduced clearance slightly. YMMV.



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I saw that but decided I'd stay with the stock mount to start when I ordered. Now that I have it I see the problem. The suggestion of v-brakes though got me thinking about how these cantis aren't great compared to my Campy Chorus road bike brakes and maybe v-brakes would be an improvement anyway. Plus I have new rims so new brakes + new rims should be a nice ride for the city.

So another question for anybody that knows, are the Avid Single Digit 5 ($20/pair) any good? Or how about the next step up and the SD 7 ($50/pair)? Or should I stick with Shimano? Or Tektro, I have a pair of Tektro road brakes on a bike and they are great. For $55 I could have a whole new brake setup, and new shifters as well. What I have is almost 25 years old at this point and from what I've seen of the newer gear even on cheap bikes is that it works well. I can't say that for my old LX.......

I've put lowly Shimano Altus V-brakes on a couple bikes and they worked great. I put Deores on my TREK and honestly can't say I can tell any difference in performance between them and the Altus V-brakes. They look nicer and cost more, for a recreational rider or commuter I 'd go with the Altus or Acera. If I was a hardcore MTBer it might be a different story.

Depending on your frame size you might have to put a brake booster on the rear brake to stiffen the seat stays due to flexing. It's a horseshoe shaped brace that goes on the brake mounts. I did on my '97 TREK 820 with 21 inch frame but the wife's 16 inch 820 was fine without. I also had to put clamp on cable stops on the top tube just in front of the seat tube for the back brake but it was worth it, the V-brakes work SO much better than the OEM Altus cantis. Origin 8 has some nice aluminum single stops for the cable. If you want I can get some pics of the brake booster and cable stop.
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Last edited by Murray Missile; 01-21-14 at 08:38 PM.
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Old 01-22-14, 01:02 PM   #24
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Why not try flipping your light mount upside down? It will go under the straddle cable, and hopefully be far enough above the tire so that you can still mount fenders if you so wish.
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Old 01-22-14, 02:00 PM   #25
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Why not try flipping your light mount upside down? It will go under the straddle cable, and hopefully be far enough above the tire so that you can still mount fenders if you so wish.
I had tried that and it was too low. Even if it had cleared the tire or fender, you need clearance for the light beam itself. These lights aim ALL the light downward.
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