comradehoser

can someone please settle this for me. I'm getting mixed messages regarding wide profile cantis from Paul and from velo news?

to quote from Paul: "These are very powerful brakes, and have a tendency to over power thin tubed frames (in any material). For none-too-stout frames and forks we recommend our Touring Canti."

to quote from velo news: "There are some trade offs with this style [wide profile]; the two most common complaints pertain to setup and lack of power."

I understand the high straddle = better clearance/less power. Thing is I tried Kores on a Jamis supernova with stock pads and the straddle set as low as possible (highest mechanical advantage, right?) without touching the wheel, and still couldn't lock up the wheel (they also didn't squeal, though). So what gives? Is it just the design of the individual brakes?

auk

Get the dual compound KoolStops. Also, give the pad time enough to bed itself to the rim. Braking should be much better.

Lycc825

I hate to bring up an old thread, but reading an article on the Avid Shorty Ultimate canti brakes confused me again.
SRAM (Avid) says that narrow profile/stance brakes have higher braking power.
Paul Component says that their touring brake have less power then their wide profile canti brakes.
I'm getting mixed conclusions while trying to search for an answer. Is braking power between wide and narrow profile canti brakes determined by the specific brand or the generic design?
Which one has more power?

billydonn

Good question. I hope someone will chime in. My experience with cantis is limited but I am guessing design is the universal factor and is more important than the manufacturer. I can tell you this: the Shorty Ultimates set up wide in front work very, very well and are balanced for stopping power front to rear.

I would speculate that pad to rim compatibility also has a lot to do with the effectiveness of these brakes.

cs1

I was always was told wide profile had more stopping power. That stopping power came at the expense of heel strike especially on the rear. That's why Paul says use the touring model canti on the rear.

cs1

WOW, that's a whole lot of Lemonds going on here.

Andy_K 

This question had me scratching my head and going back to re-read Sheldon Brown's article on the subject. I don't know that I figured it out, but I did find some clues.

First, the key factor seems to be the yoke angle. This is particularly true in the case of the Shorty Ultimate, since the ratio of the pivot-cable arm to the pivot-short arm will be about the same for either wide or narrow setup. In general, I think it's easier to set up a wide profile brake with a low yoke angle than it is with a narrow profile brake. So this is why the general received wisdom and the Paul Neo-Retro description indicates that a wide profile brake is more powerful.

The Velo News article is gone, but I looked at the Avid Shorty Ultimate manual. The thing that jumped out at me there, is that they specifically tell you to set up the yoke 20 mm higher for the wide profile stance than with the narrow profile stance. If you do it that way, then Avid is probably correct in saying that the narrow stance is more powerful.

The real gem I came across in my investigation is this:

https://www.circleacycles.com/cantilevers/

It's a visual mechanical advantage calculator for cantilever brakes. I am definitely trying this thing out at the next possible opportunity. If it's correct, wide profile brakes are more powerful than narrow profile brakes for high yoke heights, but both get more powerful as you lower the yoke and the narrow profile brakes start climbing the curve sooner (depending, of course, on the relative cable bolt height).

I could be interpreting all of this incorrectly.

ratell

Zinn discusses this in his column:

https://velonews.competitor.com/2010/...shudder_147730

meanwhile

That's an excellent link; thank you.

I'll add:

1. None of these braking systems are magic. More power = less brake shoe movement = less room for mud clearance with all of them.

2. As that source says, losses in cable flex etc are very important. The only real free lunch is reducing these. A good cable path, a fork mounted canti hanger and maybe brake boosters can transform a cheap set of cantis.

3. Yes, good pads are important too! And a well-maintained rim for them to grip.

TXBDan

Its force versus distance, simple as that. Think of a teeter totter. If you want to apply a large force on the fat kid down at the other end, you better scoot way back or lengthen your lever. By lengthening your lever, you'll have to move a greater distance in order to exert the needed force. The extra force didn't come from nowhere

Yoke angles all the stuff in the middle don't matter, the end of it all is how far the pads are moving which is inverse to their force. If your pads are moving a lot of distance, they're not applying a lot of force. If you adjust them so that theyre now moving a shorter distance, you're applying greater force.

So generally wide cantis move a lot more, so they apply less force.

Andy_K 

Actually, it's not quite as simple as that, because you can set a wide profile canti up so that it moves a lot, or you can set it up so that it doesn't move much at all. That's where the yoke angle comes in. The same is true of a narrow profile brake, although it's harder to get it set up to move a lot.

The other factor to be considered is that if you have the brake set up to move too little you can run out of cable before you're applying all the force you're capable of at the lever.

fietsbob

Higher leverage = less motion towards the rim, for a given cable pull from the lever,
aero levers pull less cable for the given pull with your fingers, so combining the 2 gives you leverage ,
but the brake lever is close to bottoming out against the bar

add interrupter levers that are much lower leverage, in the middle.

and brake adjustment is quite a collection of compromises.