# Cantilever Question



## Chainstay (Mar 13, 2004)

I am running Shimano cantilevers on my winter bike and I find them extremely mushy. The set up is Ultegra 6500 levers and early 1990's Shimano low-profile Cantilevers, see picture. I am using Swiss Stop yellow pads on Aluminum rims. The bike sees a lot of wet, snowy, sandy, salty messy conditions.

I have four questions about switching to a cross style brake like the Tektro CR 720 or CR 710

1. Will they work on these canti bosses. The bosses look to me like they may be too low on the fork for the newer style canti's

2. Do the Ultegra levers have the right mechanical advantage for the Tektro calipers

3. Will the newer style work better than my current set-up

4. Should I go with the CR 710 or CR 720


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## GRAVELBIKE (Sep 16, 2011)

When you say "mushy," what exactly do you mean? Is there a lot of flex in the system (brake bosses "bowing")? Do you have to run the pads very close to the rim so the levers don't bottom out?


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## Chainstay (Mar 13, 2004)

The levers bottom out. Because my wheels are not dead straight I can't get the pads really close to the rim. Once the pads engage the rim the levers are about 40% of the way to the bar. It's not hard to squeeze them right to the bar and I still don't feel like I'm getting the braking force on the rim that I do with the caliper brakes I have on other bikes.


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## 251 (Nov 2, 2009)

This should help: Adjusting Traditional Center Pull Cantilever Bicycle Brakes


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## onespeedbiker (May 28, 2007)

Chainstay said:


> The levers bottom out. Because my wheels are not dead straight I can't get the pads really close to the rim. Once the pads engage the rim the levers are about 40% of the way to the bar. It's not hard to squeeze them right to the bar and I still don't feel like I'm getting the braking force on the rim that I do with the caliper brakes I have on other bikes.


If your wheels are so untrue they are affecting your brake adjustment, then you need to straighten them out. This is probably the reason your brakes feel mushy; cantis like most brakes need to be adjusted close to the brake surface. Generally there is no difference between between canti brakes, so upgrading will not produce any improvement. A while back I was talking with a Paul rep, asking if their cool looking cantis would work any better than my Dia Compe 987s and he honestly said no, both work about the same. So, true your wheels adjust your brakes and they will work better.


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## Chainstay (Mar 13, 2004)

I believe that I have the set-up the best that I can practically get. I used the Sheldon Brown site and the wheels are pretty true. It's hard to get perfection with older Ksyriums.

I suspect that the Ultegra levers are not the best match to a MTB style Cantilever and that a cross specific Canti would be an improvement.


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## Kontact (Apr 1, 2011)

Chainstay said:


> I believe that I have the set-up the best that I can practically get. I used the Sheldon Brown site and the wheels are pretty true. It's hard to get perfection with older Ksyriums.
> 
> I suspect that the Ultegra levers are not the best match to a MTB style Cantilever and that a cross specific Canti would be an improvement.


Unless you know something the rest of us don't, cantis don't vary in geometry enough to change the cable pull, and road levers tend to all pull the same amount of cable, too. With a traditional stradle you can play with the geometry by varying the stradle cable angle.

Sometimes the mushyness comes from the angle the pad engages the rim. Check that you don't have too much toe-in and that the pad isn't squeezing toward the hub under pressure, rather than pushing straight in against the rim.

Tektro cantis have terrible pads in my experience. Be prepared to replace them. You might also consider replacing your current pads.


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## GRAVELBIKE (Sep 16, 2011)

Chainstay said:


> The levers bottom out. Because my wheels are not dead straight I can't get the pads really close to the rim. Once the pads engage the rim the levers are about 40% of the way to the bar. It's not hard to squeeze them right to the bar and I still don't feel like I'm getting the braking force on the rim that I do with the caliper brakes I have on other bikes.


Sounds like your levers have too much mechanical advantage for those brakes. Switching to a wide-profile like the 720 would be an improvement (I wouldn't bother with the 710s).


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## wim (Feb 28, 2005)

Kontact said:


> Sometimes the mushyness comes from the angle the pad engages the rim. Check that you don't have too much toe-in and that the pad isn't squeezing toward the hub under pressure, rather than pushing straight in against the rim..


Good advice. Also check that both pads contact their braking surfaces at the exact same time when pulling the lever. Having the pads equidistant _at rest _ doesn't always mean that they make contact simultaneously. If they don't, the first pad to hit the rim will flex the rim over towards the second pad.

Two more thoughts: I've got those very brakes (with KoolStop pads) on one of my bikes and they feel rock-hard. And although widely believed that it does, "mushiness" doesn't necessarily mean bad brake performance. Rock-hard brake feel can mean poor performance, believe it or not.


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## onespeedbiker (May 28, 2007)

Kontact said:


> Unless you know something the rest of us don't, cantis don't vary in geometry enough to change the cable pull, and road levers tend to all pull the same amount of cable, too. With a traditional stradle you can play with the geometry by varying the stradle cable angle.
> 
> Sometimes the mushyness comes from the angle the pad engages the rim. Check that you don't have too much toe-in and that the pad isn't squeezing toward the hub under pressure, rather than pushing straight in against the rim.
> 
> Tektro cantis have terrible pads in my experience. Be prepared to replace them. You might also consider replacing your current pads.


Also check that the surface of the pads match the angle of the braking surface. IOW, check that you didn't mount the pads too high or low in the brake. The best case is the brake studs should be appear to be a single rod running through the brakes when closed (your photo shows the brake studs on the outside a little lower than the pad; they should be equal. However it is more important that surface of the pad meet the surface of the braking surface.

Sheldon Brown did however say that different (non-V brake) levers have different mechanical advantages. 

*



The first factor is the brake lever itself. The lever's mechanical advantage is determined by the distance from the lever's pivot to the cable end, and by the effective length of the brake lever from its pivot to where the rider's fingers grip it. Typical mountain-bike type brake levers give a mechanical advantage of around 3 1/2, old-style drop-bar levers around 4, and "æro" drop-bar levers around 4 1/2. Levers for direct-pull ("V-type") brakes are around 2.

Click to expand...

*Finally I'm wondering what you are expecting from your cantis, by definition they require more hand strength and are more progressive, which some interpret as being mushy..


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## Kontact (Apr 1, 2011)

onespeedbiker said:


> Sheldon Brown did however say that different (non-V brake) levers have different mechanical advantages.


The point I was making is that cantilevers don't come in different mechanical advantages for use with different levers, so there is no point trying different combinations of cantis for something that will use more or less cable. The same thing applies to aero brake levers - they aren't going to vary signficantly either. So the OPs problem isn't going to be solved by replacing the lever or canti - they all use the same amount of cable for a given amount of brake travel.

Sure, he could go flat bar and use MTB levers. I don't imagine that's a real option.


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## onespeedbiker (May 28, 2007)

Kontact said:


> The point I was making is that cantilevers don't come in different mechanical advantages for use with different levers, so there is no point trying different combinations of cantis for something that will use more or less cable. The same thing applies to aero brake levers - they aren't going to vary signficantly either. So the OPs problem isn't going to be solved by replacing the lever or canti - they all use the same amount of cable for a given amount of brake travel.
> 
> Sure, he could go flat bar and use MTB levers. I don't imagine that's a real option.


That of course is true, however most of the current brifters have a higher mechanical advantage, utilizing the double pivot advantages of needing less cable. This means if you are to use cantis with these levers, you will need to set them very close to the brake surface, or you will run out of lever very quickly.


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## Kontact (Apr 1, 2011)

onespeedbiker said:


> That of course is true, however most of the current brifters have a higher mechanical advantage, utilizing the double pivot advantages of needing less cable. This means if you are to use cantis with these levers, you will need to set them very close to the brake surface, or you will run out of lever very quickly.


No, that isn't true. Shimano didn't change anything about their lever pull when they first introduced double pivot brakes back in 1991. Double pivots are straight replacements for single pivots. In fact, Campy mixes single pivot rears with double pivot fronts in many of their groups.

The current 7900 lever and those made specifically for V-brakes are the only aero levers with any interesting difference in cable pull. 

There may be some differences in cable use between different calipers, but the difference is so small that Campy, Sram, Shimano, Cane Creek, Tektro and Mavic have never modified the lever geometry to counter it.


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## Peter P. (Dec 30, 2006)

Your cantilevers are mushy because the levers don't move enough cable.

If you wish to stick with your integrated shift levers, why not try adding a Travel Agent in-line with each brake? I know they're typically used with V-brakes but they might solve your problem.


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## velodog (Sep 26, 2007)

Why are you using the yellow instead of green pads with aluminum rims?


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## Mark Kelly (Oct 27, 2009)

Kontact said:


> The point I was making is that cantilevers don't come in different mechanical advantages for use with different levers, so there is no point trying different combinations of cantis for something that will use more or less cable. The same thing applies to aero brake levers - they aren't going to vary signficantly either. So the OPs problem isn't going to be solved by replacing the lever or canti - they all use the same amount of cable for a given amount of brake travel.


That simply isn't true. Different cantis vary greatly in their mechanical advantage: the old Mafacs have a much highter actuation ratio than do most modern cantis. 

Consider the following two cases, in each case the vertical distance between canti bosses and rim contact point is X mm and arms are made so that when the yoke angle is 90 degrees the two sides of the yoke are also at 90 degrees to the arms. At this angle the force on each side of the yoke will be 1/SQRT2 times the cable pull force. 

In case 1 the canti arms are 2 X mm from pivot to the cable attachment so the force on each pad is twice that in the yoke cable. Total ratio is thus 2 * SQRT2, roughly 2.8. 

In case 2 the canti arms are 4 X mm from pivot to the cable attachment so the force on each pad is 4 times that in the yoke cable. Total ratio is thus 4 * SQRT2, roughly 5.6.


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## onespeedbiker (May 28, 2007)

Kontact said:


> No, that isn't true. Shimano didn't change anything about their lever pull when they first introduced double pivot brakes back in 1991. Double pivots are straight replacements for single pivots. In fact, Campy mixes single pivot rears with double pivot fronts in many of their groups.
> 
> The current 7900 lever and those made specifically for V-brakes are the only aero levers with any interesting difference in cable pull.
> 
> There may be some differences in cable use between different calipers, but the difference is so small that Campy, Sram, Shimano, Cane Creek, Tektro and Mavic have never modified the lever geometry to counter it.


I was partially referring to the below quote I previously posted 



Sheldon Brown said:


> The first factor is the brake lever itself. The lever's mechanical advantage is determined by the distance from the lever's pivot to the cable end, and by the effective length of the brake lever from its pivot to where the rider's fingers grip it. Typical mountain-bike type brake levers give a mechanical advantage of around 3 1/2, old-style drop-bar levers around 4, and "æro" drop-bar levers around 4 1/2. Levers for direct-pull ("V-type") brakes are around 2.


But Brown was talking about Aero brakes, so if there was a change it probably occurred prior to the brifters.

On a second reading I may be incorrect regarding the double pivot brakes. this from Jobst



Jobst said:


> The dual pivot brake achieves both greater leverage and the ability to work with smaller pad-to-rim clearance by its improved centering. It achieves this by using two pivot points to define a line of action about which its two arms are constrained to move equally, meaning they remain centered. This feature is essential in reducing the pad-to-rim clearance needed for a higher mechanical advantages of about 5.6:1.


Since most Caliper brakes run 1:1 and levers 4:1; when I read that the dual pivot brakes with a 5.6:1, I assumed it was due to some increase in the lever. I realize now that was probably wrong. Further, I am now running a 2005 Veloce dual pivot with Victory levers and they still have what seems to be twice the stopping power.


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## Chainstay (Mar 13, 2004)

velodog said:


> Why are you using the yellow instead of green pads with aluminum rims?


Apparently they are better in the wet. I see a lot of snow.

They seem to be softer and they wear fast but if they stop better I'll take the wear


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## Kontact (Apr 1, 2011)

Mark Kelly said:


> That simply isn't true. Different cantis vary greatly in their mechanical advantage: the old Mafacs have a much highter actuation ratio than do most modern cantis.
> 
> Consider the following two cases, in each case the vertical distance between canti bosses and rim contact point is X mm and arms are made so that when the yoke angle is 90 degrees the two sides of the yoke are also at 90 degrees to the arms. At this angle the force on each side of the yoke will be 1/SQRT2 times the cable pull force.
> 
> ...


I didn't say that different brakes don't have different mechanical advantage, I said that different brakes don't come with such different advantages that they are paired to specific levers. Yet V-brakes won't work with regular levers, so we have special long pull levers just for them. Nothing like that is necessary to run a Mafac or a tiny 986.

However, the distance from the arm to the pivot to the arm end is often much closer than they appear. The old style brakes have long horizontal arms that stick out a long way from the pad, but are actually the no longer from the pivot than shorter looking modern brakes whose arms are half the distance from the pad.

Anyway, the OP's problem is that he is running out of cable. He is already using fairly short cantis, and the only thing that is going to make that better is an even shorter cantis, not longer.


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## Mark Kelly (Oct 27, 2009)

Kontact said:


> cantis don't vary in geometry enough to change the cable pull, <snip>





Kontact said:


> I didn't say that different brakes don't have different mechanical advantage,<snip>


Since cable pull requirement is determined by mechanical advantage, I cannot reconcile these two statements.


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## Kontact (Apr 1, 2011)

Mark Kelly said:


> Since cable pull requirement is determined by mechanical advantage, I cannot reconcile these two statements.


That's because you are taking them out of context. The first quote is specifically about differences great enough to make different levers necessary.


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## Mark Kelly (Oct 27, 2009)

OK then I don't understand what you are saying.


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## Mark Kelly (Oct 27, 2009)

Chainstay said:


> 1. Will they work on these canti bosses. The bosses look to me like they may be too low on the fork for the newer style canti's
> 
> 2. Do the Ultegra levers have the right mechanical advantage for the Tektro calipers
> 
> ...


1. Check the vertical distance between the centre of the canti bosses and the centre of the rim. It should be 30mm.

2. Close enough.

3. Yes

4. If my calculations* are correct, the 710s will be slightly better in your setup.

*A while ago when I was looking at putting cantis on the touring bike I'm building for my wife, I wrote a sreadsheet which calculates the relationship between mechanical advantage and yoke length / angle for different cantilevers. I then changed my mind and decided to go disc for here bike. 

Looking at the spreadsheet again I find that I've forgotten the rationale behind some of it but from what I can see the CR710s will work best with the limited cable pull from the levers you have.


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## Kontact (Apr 1, 2011)

Mark Kelly said:


> OK then I don't understand what you are saying.


My answer was the same as your: "2. Close enough."

Or: All cantilevers are road lever cable pull compatible. Sure, they vary a little, and can be varied just by straddle cable angle. In fact, straddle cable angle has more influence 


Where did you find the pivot to cable binder length of the 710 and 720 to pronounce one better than the other for the OP? As far as I can tell, every cantilever can be made to act like any other simply by changing the straddle cable angle. The only limitation is the straddle touching the tire.


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## Mark Kelly (Oct 27, 2009)

Kontact said:


> As far as I can tell, every cantilever can be made to act like any other simply by changing the straddle cable angle. The only limitation is the straddle touching the tire.


That's where we differ. You have made an assumption that every cantilever can be made to act like any other, I have measured the mechanisms and calculated the forces involved and can show that there are significant differences between them.

Look at the example I posted the first time: those two mechanisms are significantly different from one another. There is no way that simply changing yoke dimensions can make one act like the other.


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## Kontact (Apr 1, 2011)

Mark Kelly said:


> That's where we differ. You have made an assumption that every cantilever can be made to act like any other, I have measured the mechanisms and calculated the forces involved and can show that there are significant differences between them.
> 
> Look at the example I posted the first time: those two mechanisms are significantly different from one another. There is no way that simply changing yoke dimensions can make one act like the other.


Then consider the following three set-ups.

1. 66mm cantilever arm at 38 degrees. Straddle cable angle 23 degrees.
2. 81mm cantilever arm at 65 degrees. Straddle cable angle 31 degrees.
3. 60mm cantilever arm at 80 degrees. Straddle cable angle 11 degrees.

With these combinations, 11mm of vertical straddle movement will produce 5 degrees of canti arm movement. 

If the cable pull of the lever (11mm) produces exactly the same cantilever/brake pad movement of 5mm, is the mechanical advantage different or the same?


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## Mark Kelly (Oct 27, 2009)

There are two things wrong with that argument:

Firstly, being able to find two or three canti systems which can be made broadly equivalent by changing yoke length does not allow you to say that all such systems are therefore interchangeable. It's called generalising from the specific and it's a common logical fallacy. All I need to do to disprove it it to give an example of two systems which are not interchangeable and I have already done that.

Secondly, your method gives the average of mechanical advantage over the range of motion. It does not guarantee that the rates of change of mechanical advantage with cable pull are also equal and in fact they are widely disparate. This will affect the apparent modulation of the brake amongst other things.


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## wvucyclist (Sep 6, 2007)

I agree with 710's, 720's stick out too far for my preference. The newer v style pads are way easier to adjust too.

On a tangent, what model Waterford is that? can you show some more pics?


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## Kontact (Apr 1, 2011)

Mark Kelly said:


> There are two things wrong with that argument:
> 
> Firstly, being able to find two or three canti systems which can be made broadly equivalent by changing yoke length does not allow you to say that all such systems are therefore interchangeable. It's called generalising from the specific and it's a common logical fallacy. All I need to do to disprove it it to give an example of two systems which are not interchangeable and I have already done that.
> 
> Secondly, your method gives the average of mechanical advantage over the range of motion. It does not guarantee that the rates of change of mechanical advantage with cable pull are also equal and in fact they are widely disparate. This will affect the apparent modulation of the brake amongst other things.


You know, you are completely right. From a mathematics standpoint it is easier to show two extremes that are so incompatible that their mechanical advantage curves don't overlap. 

But in the real world, cantis don't come in wildly different shapes, and their advantage curves (since all of them are working in arcs) really aren't that important because they only apply themselves against the rim over a couple degree arc. And if those couple of degrees all fall well within the linear cable pull range of the lever, then braking is going to be effective. Which (going back to the point of all my posts) is why there is only one lever standard for cantis. No one makes cantilevers that can't easily be set up to work effectively with any lever not specifically designed for some other use, like V-brakes.

And my example just demonstrates the considerable authority straddle height has on changing the travel and feel of any cantilever. The three examples I gave were all over the place in size and shape, not a narrow example at all. 

The OP may consider raising the straddle height on his current brakes to increase their travel for the available cable pull.


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