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I understand that there are 2 brake lever cable pull standards:

  • Standard Pull Levers
  • Long Pull Levers (for V-brakes and disc brakes)

But what is the actual difference in pull? And specifically: what is the maximum travel caused by the lever on the cable (in mm or in inch)?

brke lever pull diagram

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Thanks for that diagram, after wanting to point you at the terminology question I found that neither term was in it... fixing that now –  Mσᶎ Mar 19 at 23:43
    
Weird, I can't find this information anywhere. Although, unless you're building some leavers I can't think of a reason you'd need to know. Unless you're just curios, which is perfectly valid. –  alex Mar 20 at 0:55
    
I dare say that the majority of levers are designed together with a calliper and that there isn't a definitive spec for this. –  alex Mar 20 at 0:56
    
Is it possible its not commonly specified as the mounting location and shape of bars it mounted to affect the travel? Also, the location of the grip relive to the bars at the point the brakes contact is important to determine the useful pull. A lot of variables out of the control of the manufacturer of the lever. –  mattnz Mar 20 at 1:26
    
@mattnz: I don't think that would be the case, since you need to be able to pull the brake cable some standard amount of mm in order to fully activate the brake. There might be extra pull depending on the mounting, grip, etc, but you'd need to have at least the minimum for that standard kind... There's also lever ratio issues (pairing long pull levers with short pull brakes would require very strong hands) –  freiheit Mar 20 at 1:32

1 Answer 1

A long pull lever (i.e. for V-brakes, mountain mechanical discs) pulls the cable about twice as long (but about half as hard) as a short pull lever (caliper, cantilever, road discs).

This is determined by the distance between where the cable ends and where the lever pivots. According to this thread, its significantly lower for short pull than for long pull with some variation (it seems like under 30 mm is a cutoff for short pull to long pull if you're picking a lever out of the bin). Park Tool states that the distance from cable end to lever pivot is around 21 mm for short pull (around 42 for long pull lever), and with a 20 degree movement (think the cable end to lever pivot distance as a radius of a circle - with this radius, and the angle at which the lever bottoms out, you can calculate the total possible cable pulled), you pull about 7 mm of cable for short pull (versus 15 mm for a long pull lever).

Obviously, there is some flexibility in this parameter, allowing different manufacturers to design different cable pulls to get different sorts of lever feels. This can also be adjusted on the fly with systems like Avid's Single Digit line of brake levers. Someone claims the adjustment on the Avid Single Digit levers is enough to run short pull (YMMV). Usually when you buy a brake (or lever) from Shimano or SRAM, the manual specifies an "optimal" lever (or brake) to pair with.

If you run long pull lever with short pull brakes, it will be easy to pull the brake, but very hard to apply braking force with a hard lever feel. If you run short pull lever with long pull brakes, you will likely bottom out the lever before stopping (or lock up the wheel) with a soft lever feel. So, make sure to match the pull of the lever with the brake for your safety (obey the manual, except at your own risk!).

You can switch between the systems with a travel agent. Some levers also have a switch which can work with both types with the flick of the switch (Shimano ST-EF65 shifters+brake levers, for example).

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As a practical matter, unless you're building brake levers or have a pile of them laying around that you can't just google the model number of (in which case they were either pulled off BSO's or are probably old enough to be only short pull) or know a priori what kind of cable pull they have, why would you want to know this? –  Batman Mar 20 at 5:46
    
Knowing that the pivot distance is 21mm for short and twice that for long is probably the best way to distinguish the two "in the wild". That distance can be eyeballed fairly easily -- 0.8 inches vs 1.6 inches from centerline of cable to pivot. (This is assuming that the mechanism isn't concealed in some gaudy plastic housing.) –  Daniel R Hicks Mar 20 at 18:25
    
I'm curious as to when you'd have to realistically distinguish them in the wild based on pivot distance in the first place, though –  Batman Mar 20 at 21:30
    
When you're trying to figure out compatibility between unbranded components, especially ones pulled out of the odd parts box. –  Daniel R Hicks Mar 20 at 21:34

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