As long as the end of the catilever is above the pivot lowering the stradle increases the mech advantage. The static force analysis is cleaner if you do it with vertical and horizontal components. The vertical force at the cantilever end is always 1/2 the tension in the brake cable, and that component of the total torque is invariant. The horizontal force at the cantilever end tends towards infinity as the straddle cable approaches horizontal. The lower it goes the higher the force and so that component of the total torque increases as the straddle cable is lowered. QED
On Sunday, May 18, 2014 8:46:46 PM UTC-7, Paul Clifton wrote: > > Maybe I should make a new topic for this since cantilever brake set up is > one of those witchcraft kind of topics, but I'm posting it here anyway. > > I think shortening the straddle cable only increases mechanical advantage > for low to medium profile cantilever brakes. The CR720 is a wide profile > brake, according to Sheldon's definition (cantilever angle greater than 90 > degrees), and Sheldon's article deals primarily with low/narrow profile > models. > > For the CR720, raising the straddle cable hanger moves the yoke angle > closer to 90 degrees and lowering it does the opposite. Can anyone show me > otherwise, or tell me a reason why that doesn't matter? I've been confused > by all the mixed information for a while now. > > From my own experience, I like how the CR720s feel with a very high > straddle cable, and Riv seems to set them up that way as well. > > Paul in ATL > > -- 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. 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.
