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I am looking around for an old mountain bike to ride this winter (and this summer when it is wet).

I was just browsing around and was curious what the difference was between

Direct pull brakes:

enter image description here

And Center-pull Cantilevers:

enter image description here

Sheldon Brown has a good description of both kinds of brakes but he does not give pros and cons. Or suggest which are better.

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The main reason that the direct pull (V brake) was invented is that it approximates a center-pull cantilever in terms of balanced force and leverage, while not requiring that the cable be anchored at some point above the wheel. This is important for front wheels on suspension forks, but not significant for most other uses.

Another slight advantage of the V brake is that it doesn't generally protrude out of the profile of the bike quite as much and is thus somewhat less likely to be damaged in off-road use.

Neither advantage is of any importance for a road bike without a suspension fork. However, there is the problem that the two require different levers (because the cable travel length is different) and the old cantilevered levers are getting hard to find, should you break one.

  • 3
    You've missed out the main marketing point of direct pull. By having the bowden cable pull in the same direction as the direction of travel on the brake, more of your pull translates of braking power (some physics fluff about F being proportional to the normal (perpendicular) force). Centre pull loses about a third of the pull by pulling upwards as well (which is useless). – Aron May 14 '15 at 15:41
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    @Aron - You must have missed the place in physics class where levers were explained. Arguments about perpendicular force, et al, are pure bull -- work = force x distance. Period. – Daniel R Hicks May 14 '15 at 22:03
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    I must have missed that class between Quantum Mechanics, Advanced Particle Physics and General Relativity. I always thought that E = F . x or E=Fd cos theta. The fact that the Bowden cable pulls at an angle to the two arms of the Y made me think that cos theta was no longer unity. Thank you for schooling me in basic Physics. – Aron May 15 '15 at 5:26
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    Besides, this has nothing to do with the work function on the brake pads, but the normal contact force of the on the brake pads and the coefficient of friction. – Aron May 15 '15 at 5:31
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    Moment is conserved in a lever. That means that you could increase the leverage as much as you like, but the travel of the pad would decrease, the result is much smaller tolerances. – Aron May 15 '15 at 12:16
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...where to begin!

So much was wrong with cantilevers and linear-pull came along and made the cycling world a happier place.

This list will grow, but, as I remember, the following things were morally wrong with cantilevers:

the front cable often routed via the stem on a pulley hidden inside the stem. Over time this pulley would fray the cable and the cable would break on the front brake with no external signs of anything wrong.

Unless a reflector bracket or mudguard was in the way, the broken front brake cable would release the stirrup wire to then catch against the front wheel. This would cause an instant straight-over-the-handlebars disaster.

Even in peace-time the arrangement was not too good, the brake adjustment depended on stem height.

Some bikes did not use the stem to hold the front brake cable. Instead they used an extra bracket in the headset. When suspension came along a bracket had to be added to the forks to hold the cable.

The bolt at the end of the cable holding the yoke that connects to the straddle wire was also a bit of a problem. Typically these were setup crooked. In use the stirrup could get knocked to one side, compromising the brake balance.

As for the rear brake, the big problem on early models was how they stuck out to catch your heel. This was solved when Dia-Compe came along with the 986 to replace the 983. Shimano copied the hi-rise idea shortly thereafter.

Here is a 983:

enter image description here

And here is the 986:

enter image description here

We are talking twenty+ years ago with this 'big change' to the cantilever. There were many, many iterations to get to the linear-pull brake you have today.

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    Regarding the straddle cable catching on the wheel when the main cable breaks: modern cantis don't have this problem, because they don't use a straddle cable. See Sheldon Brown's in-depth discussion: sheldonbrown.com/canti-trad.html – Mike Baranczak Jul 15 '11 at 16:05
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    @ Mike Baranczak I beg to differ with Sheldon Brown on that one - if the cable breaks above the link-wire in your stem then you are still heading for some airtime over the handlebars. You can demonstrate this for yourself if you have a headset-mounted cable stop with quick-release - the side arms still pull outwards and the cable plus link wire still drops onto the wheel. At the time I thought the innovation had more to do with ease of setup (one bolt instead of two) and better centering. – ʍǝɥʇɐɯ Jul 15 '11 at 17:42
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    Yeah, the cable would drop down towards the tire, but there won't be any tension in the cable, since at that point, only one end of it is attached to something. You might get some drag on the tire (especially if it's knobby) but it can't be nearly as bad as the old design. – Mike Baranczak Jul 15 '11 at 22:54
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Direct-pull or "V" brakes are stronger, easier to set up and maintain, and are usually considered an improved technology. Well set-up cantis are not bad, however, and the pads do last a long time.

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    Agreed. One thing: While V-brakes are more powerful, they have very little modulation, so it takes a more skilled rider to control a stop well. But canti's aren't as powerful, and may not stop you in time at all. Most consider V-brakes to be the better choice. – zenbike Jul 15 '11 at 3:56
  • I've seen some people run rear v-brakes on mountain bikes a hair off center to compensate for grabbiness. Obviously, the downside is that it wears on one pad more. – krs1 Oct 26 '11 at 20:20
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    "Power" vs "grabby" is a design trade-off based on the geometry of the levers involved. V-brakes are mostly designed to have more "leverage" and thus you get more force on the pads for a given brake lever force. This makes the brake "grabbier" and with less modulation. Simply changing the brake levers slightly (the distance between pivot and cable attachment) would change this -- has nothing to do with the overall scheme. (I suspect that Shimano chose to make the brakes "grabbier" to be more "impressive", even though they are often too "grabby" for good bike control.) – Daniel R Hicks May 15 '15 at 12:12
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Difference on canti and v brake's can be affected by your use, which is implied but not explicit in some of the responses.

Canti pull ratio works with the pull ratio of road bikes--which is why they are used on cross bikes--not because of mud clearance since cross bikes use road brake/shifter levers.

You can use V-brakes with a road brake/shift lever but it requires the use of a travel agent to alter the cable pull from the cant ratio to the V brake ratio. These can be complicated to install, don't always work well, and can become fouled in the mud of cyclocross.

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I believe one pro of canti's are that they tend to have more mud clearance. I think that is one of the reasons that cyclocross bikes run them, at least until they started allowing discs.

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    Mud clearance, for either canti's or V-brakes, is a function of brake boss placement and for design. Both are pretty equal in this category. – zenbike Jul 15 '11 at 3:54
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Looking over all the very good answers I noticed one important omission. That is: inherent in the setup of most(*) front cantilever brakes is the potential for horrendous brake shudder. (I recently changed from cantilever to v-brakes on a road tandem just for this very reason, and it was very effective!)

Lennard Zinn explains the mechanics of it here:

Brake shudder is widespread because it’s built into the design of almost all ’cross bikes; it’s inherent to the design of a center-pull cantilever brake. To understand the reason why it happens and why reduced pad size, lots of toe-in, and a tight headset help take a look at the chart titled “Brake Shudder in cantilever brakes.”

As the brake is applied, the ground applies a force directed backward on the tire as shown, causing the fork to flex backward. Problem is, the brake cable is fixed at one end at the brake caliper and at the other end at the cable stop above the headset (as you can see in my case, at a cable hanger attached to a bolt on the stem face plate).

Think “bow and arrow” and imagine the fork between the cantilever bosses and the top of the headset is like the bow, and the cable is like the string. As the fork flexes back due to braking, the cable tightens like the string in the bow, because its two ends – the cable hanger and the brake calipers, have moved further apart. So even though you may have pulled the brake lever carefully enough to modulate it properly, as soon as the pad slows the wheel down, the fork flexes back and tightens the cable, which in turn pulls the pads harder against the rim. This in turn flexes the fork back further, which tightens the cable more, which pulls the pads harder against the rim, and so on.

Eventually, something has to give: Either the tire must slip on the ground, the rider must go over the handlebars, or the pads must break free from the rim. It is the latter that creates the shudder, the pads bind and release, bind and release, each time allowing the fork to flex back and forth and the tire to roll and stop, roll and stop. This is why the problem goes away in mud and wet sand, because the pad can break free smoothly. It is also why smaller pads with more toe-in help.

Read more at http://www.velonews.com/2010/09/news/cyclocross/technical-qa-with-lennard-zinn-return-to-cross_101807#pihaQukm0PBYREp7.99

(*) mounting the cable stop to forks instead of the headset will solve this problem.

protected by Community Jan 19 '17 at 2:16

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