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.
On Friday, February 20, 2015 at 3:09:18 PM UTC-8, Clayton wrote: > > 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 > <javascript:>> wrote: > > > 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. > > > 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. > > On Thursday, February 19, 2015 at 7:33:03 PM UTC-8, ted wrote: > > 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. > > > On Thursday, February 19, 2015 at 6:56:40 PM UTC-8, Deacon Patrick wrote: > > 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 > > -- > You received this message because you are subscribed to a topic in the > Google Groups "RBW Owners Bunch" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/rbw-owners-bunch/5HXsqAEXrWM/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > rbw-owners-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at http://groups.google.com/group/rbw-owners-bunch. > For more options, visit https://groups.google.com/d/optout. > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. 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