(Sorry for the delay and the perhaps overly pithy replies above, I was trying to get up to ten posts to lose the restrictions, but then I ran into the 5 post/day limit. Doh! No more posts another 7 hours…)
Originally Posted by
grizzly59
Start here, read the PDF Brakes- installation instructions. If there's enough pad left looks like you readjust the main cable.
Err, yes, I'd reviewed that before the initial post.
(I even linked to it in a post above that appears to be stuck in moderation—responding to LV2TNDM's q about V or cantilever — oops. Maybe it'll show up soon.)
It doesn't really say anything about how pads should be spaced away from the brake arm -- the 1mm dimension given is a
vertical one, the top of the pad should contact the rim 1mm down from the top of the rim — no manufacturer’s guidance on the rim/pad spacing during motion. (I suppose this depends on the lateral truing runout, but still).
Even so, like basically all the literature, it doesn't give any guidance on what to do if, months after the initial setup, a partially worn brake pad no longer provides sufficient friction when the barrel adjuster is maximized.
As noted in this thread, the two choices seem to be moving around the spacers and adjusting the brake cable.
Actually, I thought it was interesting that the Tektro instructions don't seem to say anything about setting the brake cable tension. Just the torque for the anchor bolt (6-8 Nm).
Originally Posted by
hokiefyd
For example, low profile cantilevers, like the Oryx brakes, usually respond well to a wider brake arm splay at rest. In other words, install the pads with the thickest spacers to the inside of the brake arm (which moves the pad closer to the rim, right?). This forces you to set the arms wider apart, which minimizes the loss of mechanical advantage that low profile cantilevers experience as they're actuated (pulled together). Your straddle cable will also generally sit lower with a straighter path between each arm (assuming you have the tire or fender clearance), which increases mechanical advantage.
Hrmm, I am confused by this — what is the adjustment that controls the width of the arms apart ("arm spacing")? As far as I'm aware, the Oryx adjustments are:
• Spring-pin pivot boss hole. Instructions say to use the middle, but nothing stops you from the others.
• Brake pad positioning via the threaded stud from the pad that has…well quite a few degrees of freedom: up/down; a little bit of side-to-side (slot is wider than the stud); rotation around the stud; and then—gosh, what's the nomenclature?—the ability to wobble off-axis from plane of the brake arm by a few degrees because of the conical spacers, which lets you set toe-in and match the angled plane of the rim.
• Brake cable tension
• Spring tension adjustment (2mm Allen key)
None of these seem to be about arm spacing?
Also, I vaguely recall reading some people suggest about not using the supplied "link wire" and instead fashioning some kind of alternative? Is that what is meant here? I don't know anything about that…
The relatively small amount of pad wear over the life of the pads (in terms of dimensions you can measure) can well be taken up by the barrel adjuster up at the brake lever.
Well would that it were so, but it seems not to be.
But maybe I'm not understanding. What does "in terms of dimensions you can measure" mean here?
Also: If cable tension really is the recommended solution here, why is the answer not to install additional barrel adjusters?