I am sorry, but this analysis is wrong. It fails to take into account that the brake arms are levers, and that the arms are each shaped like an "L", with the pivot at the bend. This has the effect of changing the direction of force from vertical, at the cable ends, to horizontal, at the shoes.
There are also issue of changing mechanical advantage as the arms move, which Sheldon Brown has addressed on one of his web pages. So, what you say could be true in result, but for different reasons.
Louis Schulman Tampa, FL
-----Original Message----- From: Steve Dahlquist <firstname.lastname@example.org> Sent: Apr 16, 2004 11:05 AM To: email@example.com Cc: firstname.lastname@example.org Subject: Re: [CR]Center Pull Staddle cable question
[Howard Darr wrote: If you use a longer than normal straddle cable on a Weinmann Centerpull brake will you have less, more or a negligible change in brake power?]
Howard, With a longer straddle cable, you get LESS brake power. With a shorter cable, you have more inward component force in applying brakes. With a long cable you have more upward component. You are applying brakes inwardly, not upwardly, therefore more inward translates to more braking power. Similarly, if you have a rope stretched between two cars in neutral, and you pull on the rope, they will move toward each other. But, when you have pulled them together and the rope is pulled far from the cars forming a "V", they will not so readily continue to move toward each other, momentum notwithstanding. It's the same principle.
Steve Dahlquist Velochrome Frameset Painting V 559-592-6367 F 559-592-2585 C 559-967-3318 email@example.com 22582 Carson Avenue Exeter, California 93221 http://www.Velochrome.com
----- Original Message ----- From: Howard Darr To: firstname.lastname@example.org Sent: Friday, April 16, 2004 7:43 AM Subject: [CR]Center Pull Staddle cable question