My experience is the same as Angus's. My CR720's fit very loosely on the studs and when the pads contact the rim they pivot on the studs enough to go toe out if you do not set up the pads to be toe-in under contact and rotational load. Cured the violent low-speed shudder for me.
-Mike C On Feb 19, 7:55 am, Angus <[email protected]> wrote: > I had a set or Ribbit (typical Cyclocross brakes, Mafac copies) on my > Atlantis that did a very similar thing. > > I am not familiar with Paul's brakes so this may not apply (some > brakes have an internal bushing and don't have a bushing riding > directly on the cantilever post on the frame). Also Jim may be > entirely correct in his explanation; without researching on the > internet my mind took me down a different path. > > After fiddling around with the usual things, I noticed the Ribbits had > a lot of clearance between the cantilever post on the fork and the > inside diameter of the bushing in the brakes (a loose fit on the > posts). This allowed the toe to change; as the brakes were applied > the the force on the pads took up the clearance between the posts and > the brakes tending to rotate the brakes to a "toe-out" position. > > I changed to Shimano XT High Profile cantilevers (which have very > little slop) and the problem stopped completely. Sometimes more toe > than seems reasonable can help shuddering brakes; some things flex > more than we would like to believe. > > I tend to run the straddle cables quite high, the Shimanos on the > Atlantis I have the straddle cable about 1/2" above the lower headset > cup. The Mafacs on the Quickbeam the straddle cable is a few inches > above the lower headset cup. Makes for a very firm feel at the brake > lever. > > Angus > > On Feb 18, 9:09 pm, rw1911 <[email protected]> wrote: > > > > > I'm assuming (hoping) this is a simple setup issue... > > > I've recently installed Paul brakes (neo-retro front, touring rear) on > > my relatively new to me 700c All-Rounder. The rears are wonderful, if > > not too powerful... I can skid at will. However, I'm experiencing > > extreme shudder and fork flex on the front. > > > The headset is tight and the pads are toe'd to contact forward. Under > > low to medium speed braking, I can see/feel the fork flex (a lot!) > > and shudder. The straddle cable is set at about the top third of the > > lower headset cup. I've cleaned the rim and while it has gotten > > slightly better with use, is this a matter of adjustment or is the neo- > > retro too powerful? > > > One thing I noticed during installation is that the Paul brakes sit a > > good bit higher on the studs than the Shimano's they replaced. Could > > this be contributing to the flex in the mounting studs and/or fork? > > > Any experience/advice is appreciated.- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
