I think you guys are making this way more complicated and confusing than it needs to be.
If you want to lift something with a cable it is best to pull it in exactly the direction you want it to move. So a long and nearly vertical arm, like the neo-retros move upward in a wider, flatter arc and therefore need a higher cable set pretty close to 90 degrees to lift the arm upward. A lower profile like the Shimano brake moves more inward in a narrower arch and so will work better with a shorter cable, also set close to 90 degrees. I'm not staring at my neo-retros right now, but I believe Paul recommends a 6" high straddle and I believe that is about where mine is set. They work great. I also have both the Racers (on a my tandem) and the Racer Ms on my Rambouillet. You will get a pretty good angle at about 4" on these. That is where mine are set and they work quite well. michael On Apr 13, 2:28 am, Jeremy Till <jeremy.t...@gmail.com> wrote: > Rene, have you read Sheldon's article on cantilever geometry? > > http://sheldonbrown.com/cantilever-geometry.html#mechanical (links to > the section on mechanical advantage) > > Of course, the specifics of the article are about cantilevers, but the > information about straddle cable height should be pretty much the same > for centerpull calipers. > > The truth is, I don't think there is one "optimal" MA setting for > these types of brakes, it really comes down to the vagaries of your > personal setup and your own preferences in how your brakes feel. > Sheldon points out that the normal instincts of brake feel, coming > from cars--that a firm, stiff response in the lever is optimal-- > doesn't necessarily lead to the best brake set up here. > > MA is basically the ratio of distances traveled between lever and > pad. At higher MA's, the lever is traveling much farther than the pad > is, and thus it can feel "spongy" and worrisome. However, if you > think about it, high MA means that all that distance being traveled by > the lever is turning into clamping force at the rim, just like when > you use a simple lever and fulcrum, you push the lever a much greater > distance than the load, but produce a greater force than you could > unaided. Thus, "spongy" feeling levers can actually produce > prodigious stopping power, and have great modulation. However, with > too much MA the lever can bottom out on the handlebars. Lower MA's, > conversely, feel firmer at the lever and prevent the lever bottoming > out on the bar, but you will need to squeeze the lever harder within > that smaller range in order to produce the same stopping power as > before. So some of it comes down to hand strength, some to how your > lever interacts with the curve of your bars, and some to how you want > the lever to feel when you pull back on it. > > I would set the MA as high as is possible while maintaining what feels > to you like an okay range of motion for the lever, i.e. that doesn't > risk bottoming out on the bars. I took this to the extreme on a bike > i recently sold. It had a traditional medium-profile cantilever > (single front brake on a fixed gear) and a nice old LX mtb (pre-v > brake) lever. I basically set the straddle cable in line with the > bottom of the fork crown, so as low as it could go without affecting > clearance. The lever traveled relatively far, but MAN, could that > thing stop--it shot me forward off the seat the first time i pulled > it. > > On Apr 12, 9:37 pm, Rene Sterental <orthie...@gmail.com> wrote: > > > > > Finally figured out how to use the calculator. However, while I can see the > > MA go up or down, what is the optimal MA to strive for? I'm still > > unsure, based on all I've read, whether a lower or a higher MA are better. I > > thought I understood that lower MA meant more modulation but more force > > needed to apply the brakes; also a spongier feeling at the lever. Higher MA > > meant ligher snappier feeling that stops very quickly but looses modulation. > > > Is it then a matter of finding what you like or is there a number or setting > > to go for? > > > René -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
