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Old 10-25-08, 04:47 PM   #1
wearyourtruth
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center-pull brakes: shorter v. longer straddle cable

so if i remember my high school physics correctly (quite an "if") a shorter straddle cable on a center-pull (caliper) brake will yield greater stopping power (or at least a tighter squeeze) based on the angles, vectors, and all that jazz. however i've been told a couple times (by people who's bicycle knowledge i generally respect) that a longer cable is the key to greater stopping. i searched through here and sheldon's without any real answers. a few notes here and there hinting that my assumption is correct, but i wanted to address the question directly. anyone know for sure? thanks!


we all know what they are, i just like pictures.
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Old 10-25-08, 06:21 PM   #2
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I'm no physicist, but my gut feeling suggests that a shorter straddle cable means the brake pads will travel further but less forcefully, while with a longer straddle cable the brake bads will be closer to the rim when fully open but you'll be able to apply far greater force through them when you haul on the lever.

I might have this backwards in all kinds of ways -- please correct me if I'm wrong! They're typically set up like this for BMX, which is a looooot of straddle, either way:



Obviously different levers/cables/etc would introduce their own variances.
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Old 10-25-08, 06:46 PM   #3
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Quote:
Originally Posted by wearyourtruth View Post
so if i remember my high school physics correctly (quite an "if") a shorter straddle cable on a center-pull (caliper) brake will yield greater stopping power (or at least a tighter squeeze) based on the angles, vectors, and all that jazz. however i've been told a couple times (by people who's bicycle knowledge i generally respect) that a longer cable is the key to greater stopping. i searched through here and sheldon's without any real answers. a few notes here and there hinting that my assumption is correct, but i wanted to address the question directly. anyone know for sure? thanks!
The Geometry of Cantilever Brakes by Sheldon Brown
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Old 10-25-08, 07:47 PM   #4
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^ dang, i saw that article but i didn't click on it because it was dealing with canti's instead of calipers. i didn't even think of the fact that both can have yokes, etc.

so after reading that... shorter = more power eh?
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Old 10-25-08, 09:51 PM   #5
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Yeah, shorter means more of your brake-lever's travel goes into moving the calipers rather than just stretching the straddle-cable.
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Old 10-26-08, 12:06 AM   #6
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My suggestion is to replace the center-pulls with side pulls. Center pulls are such a pain in the rear.

Anyway, the biggest problem with center pulls is cable stretch - both in terms of maintanance as well as performance.

The shorter you can make all the cables the better including the "straddle cable" (thanks for the vocab builder) and the housed cable. Some folks tend to leave the long housed cables longer than they need to which reduces responsiveness in braking.
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