Paul Brakes -- Wow!

[Deacon Patrick]

Thanks to Peter for the new to me brakes, I just replaced the Tektro (720?) brakes (whatever was stock) on the Quickbeam with Paul Touring canti in the rear and Neo-Retro front. I still have a bit of adjusting to do with saddle cable length on the front, but Wow! What a difference! Absolutely amazing difference on my very short test ride (though I did a very steep section and they handled the down hill beautifully!). Smoother, steadier, more solid. The install a feeling of confidence. I like that in a brake. Grin.

With abandon,

Patrick

www.MindYourHeadCoop.org

www.OurHolyConception.org

[Justin August]

Well this answers my question about if I should go cheap to rebuild the SimpleOne...

-J

[Kieran J]

Hey Deac, any brake judder on the Neo front? 

KJ

[Deacon Patrick]

No brake judder in the initial wee test, and there would have been with the Tektros on that same test. I'm stunned with the difference.

With abandon,

Patrick

[Aaron Young]

How very interesting. What do you think is making the difference?  Same or different pads on each type of brake?   Of course the old ones were set up normally, right?  

In any case, I'm glad the new ones are working so well for you. :)

Aaron Young

The Dalles, OR

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[Deacon Patrick]

I attribute it to Paul's design vs. Tektro's design, though no idea what the exact difference is, the difference in the result is night and day. I'm not sure what you mean by set up the same way?

With abandon,

Patrick

[Goshen Peter]

im glad to hear they are working out. The dual compound mountain pads help reduce shudder, and of course toe in, not sure if you just left them like I had them or not but I had them toed in when I sent them out. Is your cable hanger on the crown or on the headset? it made a pretty big difference on my bombadil when I got the crown hanger.

[Deacon Patrick]

Here's a photo of the old brake set up (as I got it, I greatly lengthened the saddle cable to get better leverage.) But it shows the cable hanger location. My previous brakes were Salmon only compound, but that has worked great on my Hunqapillar. I needed to adjust the brake pad alignment quite a bit.

With abandon,

Patrick

[Deacon Patrick]

Oops. Here's the photo:

https://www.flickr.com/photos/32311885@N07/14027294429/in/set-72157644719995654

With abandon,

Patrick

[Kellie]

Curious why you went with the retro up front and the touring in the back? I switched to Paul center pulls from side pull. I had the same experience; they

are wonderful! What are the pedals you have there in the photo?

On Thursday, February 19, 2015 at 3:53:31 PM UTC-8, Deacon Patrick wrote:

[ted]

If lengthening the straddle cable from what's shown in this photo made your brakes work better for you thats great, and I wouldn't dream of claiming you were mistaken about it.

However it's also a fact that lengthening that cable reduces the mechanical advantage (i.e. leverage) of the brake. So increased leverage was not the reason you liked the change.

It's great that your new to you Paul brakes work so well. Congrats.

[Deacon Patrick]

Kellie, I went with touring in the back because I got them used and that's the set up that was available. It's a set up common to folks who want the most power for the front brake, and clearance for panniers in the rear.

Ted, lengthening the saddle cable make the angle of the brake cable to the brake arm closer to 90˚, and that definitely increased leverage. Here's what it looked like:

https://www.flickr.com/photos/32311885@N07/14450777149/in/set-72157645649878184

With abandon,

Patrick

[Deacon Patrick]

Kellie, the pedals are VO pedals. I've returned them for a refund due to bearing issues with two attempts. They worked fine for a few rides, then began clacking. Not build for single speed hill climbing on Pikes Peak, I guess. Sardonic grin. VO was great to work with in getting a second pair and then a refund.

With abandon,

Patrick

[ted]

Deacon,

The thing is, that definitely does not increase the leverage. 

The the vertical component of the tension in the straddle cable is equal to the tension in the brake cable (well half on each side).

Lengthening the straddle cable reduces the tension in it as well as changing the angle at which it meets the brake arm. The vertical component of the tension stays the same, and the horizontal component is decreased.

The net result is less torque around the brake post for a given force on the brake lever.

For a wide profile brake like the 720, where the end of the arm is barely above the pivot, the decrease in leverage is relatively small. But it is a decrease, not an increase. To get an increase in leverage by lengthening the straddle cable the end of the brake arm would have to be below the pivot.

Again I'm not claiming that the longer straddle cable didn't work better for you, just that the cause of the better can't have been increased leverage.

[Dave Johnston]

The old Tektro pad material was truly horrible, I'm not sure if they have improved it in the last few years, as even though I still buy Tektros I replace the pads before they even go on a bike.

I have Paul Neo-Retros (kool stop blk pads) on the Heron and CR720's with Salmon pads on the rSogn and think both work great. Can't tell much difference. The fork and stays on the rSogn seem beefier though, so that may help reduce flex during breaking.

-Dave

On Thursday, February 19, 2015 at 6:53:31 PM UTC-5, Deacon Patrick wrote:

[Tom Harrop]

I also didn't really like the CR720s. Tried them on two bikes, always Kool Stop salmon pads, and in the end I switched to Shimano CX70s, which are much more flexible (in theory you could set them up with more or less MA than the Tektros) and have a lot less slop on the posts than the CR720s. It's a shame 'cos I like the way the Tektros look.

From my understanding Ted is correct about the difference in leverage—and sometimes decreasing leverage is what you want. When I first set up the CX70s I had too much MA (lever bottoming out against bar) so I raised the straddle until it was right.

[Deacon Patrick]

Ted, et al engineer types: I happily bow to your knowledge on the angles and leverage, though I was told the opposite (as I understood it) before I made the change. Interestingly, either way, the experience went from slushy brakes (short saddle cable, < 90˚ intersection with the brake arm) and salmon pads, to passable strength except in single track steep descents (long saddle cable, close to 90˚ intersection with the brake arm). But that point is mute now, as the Paul's are wonderful! I look forward to snow-free trails so I can try them out!

With abandon,

Patrick

[Ron Mc]

my next purchase after I sell a couple of more rods (hopefully this weekend at TroutFest).  Only I'm using the touring on both ends to keep the width down

[Mark Reimer]

Paul brakes are the best! I race cross with a pair of neo retro's. Can't imagine ever needing more brake. I can easily lock up the wheels if I wanted too. Nice and smooth modular braking. I tried using trp cx8.4's and hated them compared to the Paul's. I'd love a pair of touring brakes on my Atlantis someday. Only brakes you'll ever need.

[Clayton]

I have to jump in here.. I have always been taught and discovered on my own, that the straddle cable should be as close to perpendicular, or at 90 degrees, to the center of the brake pad "lever" when it hits the rim. You can do this experiment on your own. Get a stick. Tie a string to it. Lay the stick on the ground and lift the string. Lift perpendicularly and then from different acute angles, inline with the stick. If you lift from acute angles, the stick slides, which is energy wasted. If you set up your brakes with a too short straddle cable, you lose feel and the leverage forces change as you apply the brakes. Starts out soft and weak, and increases as you apply the brakes because the angle gets closer to 90 degrees. Over 90 degrees, and you get weak brakes. The brake arm is just a lever. It works best, like all levers if you lift from the end at 90 degrees. The brake arm pivot placement is basic too. Long arm on the straddle cable side, shorter arm on the rim side. It does not matter at all when it comes to straddle cable length. The only lever the straddle cable acts on is the long side. The distance between the pivot and rim, and pivot and straddle cable angle is fixed and you can't change it. After 20 years plus of running cantilevers and being a mechanic for YETI cycles back in the heyday, a shop manager and mechanic, I finally gave up.  I run V-brakes now, which are much more powerful, especially with long Cool Stop salmon pads. Braking is at near disc power. I can easily do a nose wheelie, using brake power alone. The feel is so good, I can anti-lock brake the front. Apply, feel it start to slide, let loose and rebrake. The only thing I don't like and it is very minor, is the hood shape on the Cane Creek Road V-brake levers.  There is far more clearance with panniers and I don't poke my calf anymore. Everyone here loves their cantilevers. They are prettier and match the aesthetic of Rivendell. I get that, but for me the superiority of V-brakes has become beautiful in itself. 

[Justin August]

Clayton-
I too, have a love for non-canti's. Paul's MiniMotos make my heart sing.

However I was set to go with Tektros (even after a bad experience with them years ago) and this thread made me rethink. I searched locally and found a cross racer moving to Vs on his CX bike and he offloaded his Neo/Touring setup to me at a price that was far more than fair. So now my resurrected SimpleOne will be sporting Neos up front and Touring in the rear.

I personally feel that unless you are racing there's no reason not to go with Paul brakes. I've (almost) never heard a critique about their primary function (braking) in any of their multiple forms. Plus there's a wide variety to fit nearly any frame (including disc coming soon!).

I'm not into being devoted to brands but when the pattern of quality is there...

Thanks Deacon for this thread and spurring me to look for Paul's on the cheap!

-J

[Deacon Patrick]

Great find, Justin!

With abandon,

Patrick

[Tom Harrop]

I'm also pro V-brake but they just don't work with 60 mm tyres and fenders. It's gotta be cantis for me!

[ted]

Deacon,

I am glad that you were able get your brakes to work the way you want. I suspect you were told the opposite of what I am telling you, and that you understood what they were saying. Sadly they told you wrong. But happily they still steered you to something that worked for you.

The phrase "slushy brakes" suggests to me low effort producing large brake lever travel with little braking effect. If that's what you had it was likely due to elasticity in the brake system, which is a separate thing from leverage. If you experience that sort of thing, look for what moves when you squeeze the lever hard after the pads hit the rim. For example, I found the steel front cable hangers flex a lot. Replacing mine with the aluminum ones improved the feel of my brakes significantly. Cables that change shape as the brakes are applied can be another source of excess travel.

[Mark Reimer]

Deacon,

I agree with you on this. Getting the straddle as close to 90 degrees has always been the position which yielded the greatest stopping power for me. With my neo-retro's (Aka the 'weaker' of the paul canti's) I have the cable long and up high, and I have enough power to lift up the back wheel if I really wanted. 

Lower straddle usually results in less power, and obviously less mud clearance as well. 

As I understand it, the idea is to get the cable as close to 90 degrees as you can WHEN the brakes are in contact with the rim. 

To read a much more exhaustive explanation than I'm willing to regurgitate, take a look at BQ's great write-up on setting up canti's. 

In the end, I'm sure we can all agree that Paul canti's are awesome. 

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[Mark Reimer]

Oops, here's the BQ article:

http://www.bikequarterly.com/images/BQCantiSetup.pdf

[ted]

Clayton,

Your reasoning is mostly wrong, and your stick analogy does not apply.

I think you are forgetting that the straddle wire provides mechanical advantage. A small side force on  a relatively straight cable produces a large tension in the cable. In theory, if the cable is straight the leverage is infinite. If you correctly analyze any cantilever brake setup you will find that making the straddle wire flatter increases the net leverage. Unless of course the cable attachment point is at or below the pivot, but I don't think anybody makes brakes like that.

[Philip Williamson]

It's good for big-foot heel clearance, too. I have Tektro 720s on the front of my Quickbeam, and the original low-profile brakes on the rear. The rear CR720s hit my foot sometimes, so I switched that brake back to stock. 

I'd call the CR720s pretty (I like the look more than the Pauls), and adequate with a high straddle carrier and Kool Stop pads. I'd do Patrick's Paul setup, but I gathered from list eavesdropping that it's hard to make the M12 rack work with them. And I love that rack. 

Philip

www.biketinker.com

[ted]

Mark,

From the BQ writeup you cite

The angle of the straddle cable also af- fects the mechanical advantage. A low straddle cable means that the pads travel less for a given brake lever pull. Less travel means more power.

and

Unless the straddle cable is at a right angle to the brake arm, the effective length of the brake arm is shortened, which in turn reduces the braking power.

The first is pretty straight forward, but the second overlooks the fact that, for a given brake, the tension in the cable changes when you change the angle. As you raise the angle towards 90 you reduce the tension which counteracts the increase in "effective length".

I think its much simpler to work out if you decompose the cable tension into vertical and horizontal components and stay away from notions like "effective length". 

[Mark Reimer]

Ok. I'm out of my element. Going riding 

[ted]

always the best plan

[clayton bailey]

I learned this over 20 years plus of using and working on cantilever brakes. I set up brakes for mountain bike race teams in the late 80's and early 90's. I am sorry, but your armchair theory does not translate to real bikes in my experience. I run canti's on my Crux. The greatest feel and max leverage is at 90 degrees.

With abandon,

Patrick

[clayton bailey]

Oh... I forgot to mention that brake feel is more important than outright power anyway. Bikes have a small contact patch. It's important to know exactly when your tire is at max adhesion at maximum braking, and not past it. I bow out now...bye.

Clay

On Friday, February 20, 2015 2:34 PM, ted <ted....@comcast.net> wrote:

https://www.flickr.com/photos/ 32311885@N07/14450777149/in/ set-72157645649878184

With abandon,

Patrick

[ted]

Of course you should like what you like, and may believe whatever you like.

However as it seems you realize, good brakes are about more than just mechanical advantage. Though your experience has taught you that 90deg. gives the "best" brakes it does not follow that 90deg gives maximum mechanical advantage.

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[Michael Hechmer]

I also appreciate how easy it is to rebuild Paul's brakes.  All the parts are available at a reasonable cost. Last a life time. Once you get past an initial learning curve they are pretty easy to adjust and hold their adjustment very well.

Many years ago, while commuting home I was involved in a crash which was largely caused by a pair of inadequate Shimano cantis (and a crazy women in a pick up truck.).  After that I switched to a pair of neo retros.  Soon after that I was staring at a car that had made a right turn directly in front of me.  The neo retros lifted the rear wheel off the ground but stopped the bike on the spot.  I've never considered any other brakes since.  Worth every penny.

Michael

[Michael Hechmer]

I too agree. Mechanical advantage is important to avoid having the lever bottom out before the brake fully engages, but pure power will be maximized when the straddle cable is 45 degrees to the arm.  Hence the neo retros require a higher straddle cable than the touring cantis to maximize stopping power.

Michael

[ted]

Michael,

I am confused.

Are you saying that not enough mechanical advantage causes the lever will bottom out, or that too much will?

Do you agree with Mark that 90 deg. gives the best stopping power, and say that 45 degrees gives the most power?

Are you distinguishing between "pure power" and "stopping power", and if you are how do you define them?

What exactly is the "hence" that makes neo retros require a higher straddle cable?

Could you please elaborate?

[Michael Hechmer]

Sorry for the confusion, I certainly mis wrote that and maybe even mis thought it. My understanding, in a less technical way, is what Ted wrote.  In my simple minded way, here's how I envision it.  The longer a lever is from the fulcrum the more mechanical advantage it has, but that also requires moving the lever an ever greater distance across an arch in order to move the other end of the lever.  When a brake lever has too much mechanical advantage it can bottom out before the brake pads have moved enough to stop the rim.  That's what was wrong with the Shimano integrated levers and cantis I once had.  They just needed to pull too much cable to create stopping power.  

A cable 90 degrees to the end of the brake arm should in theory best transmit upward energy, but since the arm pivots in an arch and the straddle is in the center, that is not possible.  but it would seem to me that the closer you are to that through the entire line of brake arm  travel the better off you will be.  The touring cantis are already at about 45 degrees so setting the cable closer to 90 would require a lower straddle for optimum power.

This explains, to me at least, why my neo retros work best with a hi straddle and confirms Pauls recommendation of 5+ inches.

I'm happy to try to relearn classical physics & geometry but I ain't moven my straddle cable.

Michael

[clayton bailey]

If you like your brakes, THAT is how you should run them. Everything comes down to what you like in the end. After all, they are just bicycles......CRACKA TAKA BOOM!  Damn, just had to duck a thunderbolt....lol.

Clayton (Bend)

[Brewster Fong]

On Friday, February 20, 2015 at 10:26:03 AM UTC-8, Clayton wrote:

I have to jump in here.. I have always been taught and discovered on my own, that the straddle cable should be as close to perpendicular, or at 90 degrees, to the center of the brake pad "lever" when it hits the rim. You can do this experiment on your own. Get a stick. Tie a string to it. Lay the stick on the ground and lift the string. Lift perpendicularly and then from different acute angles, inline with the stick. If you lift from acute angles, the stick slides, which is energy wasted. If you set up your brakes with a too short straddle cable, you lose feel and the leverage forces change as you apply the brakes. Starts out soft and weak, and increases as you apply the brakes because the angle gets closer to 90 degrees. Over 90 degrees, and you get weak brakes. The brake arm is just a lever. It works best, like all levers if you lift from the end at 90 degrees. The brake arm pivot placement is basic too. Long arm on the straddle cable side, shorter arm on the rim side. It does not matter at all when it comes to straddle cable length. The only lever the straddle cable acts on is the long side. The distance between the pivot and rim, and pivot and straddle cable angle is fixed and you can't change it. After 20 years plus of running cantilevers and being a mechanic for YETI cycles back in the heyday, a shop manager and mechanic, I finally gave up.  I run V-brakes now, which are much more powerful, especially with long Cool Stop salmon pads. Braking is at near disc power. I can easily do a nose wheelie, using brake power alone. The feel is so good, I can anti-lock brake the front. Apply, feel it start to slide, let loose and rebrake. The only thing I don't like and it is very minor, is the hood shape on the Cane Creek Road V-brake levers.  There is far more clearance with panniers and I don't poke my calf anymore. Everyone here loves their cantilevers. They are prettier and match the aesthetic of Rivendell. I get that, but for me the superiority of V-brakes has become beautiful in itself. 

Agree! I too tried cantis (Suntour xc pro) and hated them in the front. Tried koolstop salmon pad and no difference. My fork shudder, the brakes squealed and if my Campy ergo levers weren't adjusted just right, the lever would bottom out. 

Switched out the front Suntour xc pro canti brake for a cheapie Tektro 926al v-brake, an under $20 brake, and voila, fantastic braking! No more squealing, shuddering or bottoming out!!! Made me like riding my cross bike again!  So, my next cross bike will be getting canti and I'm leaning towards Paul minimotos.  But, if money was an issue, I wouldn't hesitate to put on a set of cheapie tektro v-brake!  Good Luck!

[ted]

Z,

Thanks for this exposition. I understand this approach. The downside of it is that to get it right you must do some trig to keep track of the variation in the tangent force magnitude. The tension in the straddle wire increase the flatter it gets. Of course you never get near the theoretical infinity but it does increase, and to get the right answer from your approach you have to keep track of that and balance it correctly with the variations of alignment with your axis tangent.

Please consider another approach that I think is simpler, particularly if you want qualitative insight.

Keep the other half of the brake in the back of your mind. It's important because it balances the side forces that are inherent in any feasible straddle cable.

In stead of decomposing the cable force into axial and tangent (or perpendicular), go with up and sideways. You do this with both the straddle and the arm.

The vertical component of tension in the two halves of the straddle wire must balance the tension in the brake cable. Call the brake cable tension T, then the up force one each brake arm is T/2. This is true regardless of what the straddle cable height is, and that fact is what gives this approach its advantage.

Now unless the straddle cable is vertical there will be a side force towards the centerline of the bike. The flatter the cable the larger the force.

To get the torque about the pivot post, decompose the brake arm axis into sideways and upwards components (dx and dy if you like). The net torque is the sum of the up force times the sideways offset plus the side force times the upwards offset. 

The part of the torque from the up force times the sideways offset does not change when you alter the straddle wire height.

The part of the torque from the side force times the sideways offset always helps and always get larger when you lower the straddle wire.

Q.E.D.

Furthermore, if you look at the sideways and upwards offset lengths of different brakes in light of what you know about the forces induced on them by the straddle cable you get an accurate intuitive sense of what is going on.

With 720s or Neo-Retros the sideways offset is sizable and the vertical offset is small. Because of this these brakes are relatively insensitive to changes in straddle cable height. 

With low profile brakes like the Paul Touring model the sizes of the sideways and upward offsets are about reversed. They need the sideways force from the flatter straddle cable to generate significant torque, and the torque you get depends quite a bit on the straddle height.

High profile cantilevers do not need a high straddle wire to maximise leverage, on the contrary raising the straddle wire always reduces the leverage.

High profile cantilevers need high straddle wires to clear the tire/fender/rack. Luckily the leverage they get is relatively insensitive to straddle wire height so raising the straddle to clear whatever you need to clear is not a problem.

On Friday, February 20, 2015 at 10:42:22 PM UTC-8, Z wrote:

Ted,

Envision one half of a cantilever brake setup.  There is an axis between the points where the straddle cable attaches and the brake pivots.  We'll call this The Axis.  Now envision a force vector along the straddle cable.  If you conceptually break down that vector into components which are 1) perpendicular to The Axis and 2) parallel to The Axis, you will realize that any force parallel to The Axis will be working against the rigidity of the cantilever brake mount.  So, you really want to maximize former vector component... that is, by applying the straddle cable's force perpendicular (90 degrees) to The Axis.  Of course, you want to be maximizing this force vector as the brake pad is touching the rim.  

It's true that you can apply a great deal of tension to a straight cable by applying a force perpendicular to its axis.  However, the theoretical infinite tension doesn't really affect braking when you consider the brake pivots (and the steel frame to which they attach) resisting most of that tension, which is what you would likely achieve with a high profile cantilever and shallow straddle cable angle.  

Z

[ted]

Hey Michael,

Thanks for the nice clarification. I think I get what you mean now.

I would never dream of asking you to move your straddle cable. What works works and that's an irrefutable tautology. The explanation or rational about why it works, now thats where I have been know to dive badly down the rabbit hole and wind up in purgatory. 

regards

ted

[Mike Shaljian]

Have you considered getting Paul Motolites? I hated cantis and then switched to V-brakes, but struggled to find a reliable, high-performance V-brake. The Motolite is just that: powerful, reliable and of course pretty. I added a brake booster to the front and they are dynamite now.

[Z]

Thanks Ted,

Sorry for the tone.  Maybe pot brownies and internet forum physics lessons are things I shouldn't mix?

[Philip Kim]

I've been thinking about getting a pair as I got dirt drops. Need something a bit more stopping power than my campy cx cantis. Do you think they will fit 26x2.0 big bens?

[ted]

Zach,

I thought your tone was fine. Sorry if mine was off. I didn't mean to come off snarky or offended or anything. 

Regards

Ted

[cyclotourist]

I thought pot brownies complemented all life activities???

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Cheers,
David

Member, Supreme Council of Cyberspace

"it isn't a contest. Just enjoy the ride." - Seth Vidal

[Mike Shaljian]

I think it depends on your bike. Strangely, on my 700C (64cm) Sam Hillborne the brake pads are at the very lowest position in the huge adjustment range on the Motolites. I would love to have gone 650B on my recent wheel re-builds to get a 650X42mm tire, but the strange canti stud placement on the frame won't allow for this. Ask your LBS!

[Leslie]

Mike, I'm confused....  on my 650b Bombadil, I have Motolites, and could raise the pads to run 700c wheels with it, but to go from a 700c to a 650b (as I did w/ my Rambouillet), you have to use long-reach calipers, not canti's.... ??

[Mike Shaljian]

Indeed. Long-reach calipers was the obvious choice, don't think I'd bother though. I question the handling change at 650b on a Sam. 

[Ron Mc]

Putting in a plug here for Modern Bike.  Andy has Paul Components in stock at about 30% off across the board.  His service is excellent.