# Brake Cable Pull Ratios



## Lelandjt (Sep 11, 2008)

Shimano has gone through 3 generations of brake cable pull:
1. 8, 9, and 10 speed shifters with external shift cables pulled the least cable (Gen 1).
2. 10 speed shifters with internal shift cables pulled more cable (Gen 2).
3. 11 speed shifters pull even more cable (Gen 3).

Which pull ratio is Sram closest to? I'm guessing Gen 2.
Which is Campy closest to? I'm guessing Gen 1.
Have Sram or Campy changed their cable pull over the years?

My own experience is that there is a very noticable difference between the generations. I had a bike pieced together with free parts that combined Gen 1 brakes with Gen 2 levers and they were very wooden feeling. Sharp, solid response but required a hard squeeze to stop. Mountain V-brakes required adapaters to work with Gen 1 & 2 levers but not with Gen 3, though the pads must sit closer to the rim than with a MTN lever. TRP mini Vs have a very sharp action with Gen 3 levers but still have sufficient power.


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## JerryZ (Dec 25, 2001)

I have done a little research on this myself. I have Shimano 7700 DA 9 speed group and am planning on going to Etap sometime in future. I am reasonably sure that the current SRAM is the same as Gen 1 Shimano. As for your other questions, I don't have a clue. I do agree you need to be near the correct ratio to get proper brake function. Hope this helps. Cheers!


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## Lelandjt (Sep 11, 2008)

Weird more people aren't interested in this or knowledgable about it.


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## SwiftSolo (Jun 7, 2008)

I think if you're looking for power potential, you need to be aware that shimano has traditional been a regressive pull ratio while campy has been progressive (shimano's pull cable at a higher rate the further you pull the level while campy pulls cable at a lower rate). Another way of putting this is that shimano operates on the back side and moves toward TDC while campy starts at top dead center and moves to a more powerful position the further you pull (less pull rate). Not sure about sram.

Just be aware that the pull rate changes significantly as the lever moves.


Lelandjt said:


> Shimano has gone through 3 generations of brake cable pull:
> 1. 8, 9, and 10 speed shifters with external shift cables pulled the least cable (Gen 1).
> 2. 10 speed shifters with internal shift cables pulled more cable (Gen 2).
> 3. 11 speed shifters pull even more cable (Gen 3).
> ...


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## Lelandjt (Sep 11, 2008)

If that's the case than Shimano's road levers work opposite of their mountain levers and contrary to what would make sense. Why would they want less leverage the farther you go into the stroke? Servo-wave is their more cable pull at the beginning to bring the pads in, then less for for power system. Their mountain cable levers have used it since 94ish and most of their hydro levers use it. Weird they'd go the other way for cable road levers.


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## SwiftSolo (Jun 7, 2008)

I have XTR levers on my mountain bike that are regressive (admittedly they are 15 years old). 

It's real easy to check. Cable pull brake levers basically act as elliptical cams with the lever pivot point being the center of the cams shaft. When the pull angle (relative to the pivot point) is greater than 90 degrees and moving toward 90, that is regressive. When the pull angle starts at or less than 90 and moves toward zero, that is progressive.

To be clear, I'm pretty sure that shimanos brakes have become less regressive in the past 5 years and may have moved to the progressive side. In 2010 they were clearly regressive and that was instrumental in my decision to build my tarmac s-works sl3 using a Record groupo (less calipers) . I used their "brifters" with Eebrakes and had what were the best road brake combination avaialable at the time (still far short of hydro discs).


Lelandjt said:


> If that's the case than Shimano's road levers work opposite of their mountain levers and contrary to what would make sense. Why would they want less leverage the farther you go into the stroke? Servo-wave is their more cable pull at the beginning to bring the pads in, then less for for power system. Their mountain cable levers have used it since 94ish and most of their hydro levers use it. Weird they'd go the other way for cable road levers.


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