On Wed, Jan 21, 2009 at 10:09 AM, Jan Heine <heine94@earthlink.net> wrote:
> If all brakes were equal, then why did so many racers switch to Mafac
> centerpulls almost immediately after they were introduced? From what I have
> heard, Mafac did not sponsor anybody, the racers had to buy the brakes with
> their own money...
>
> From that, I conclude that the 1940s sidepull brakes were pretty lousy. By
> the 1960s, when Campagnolo introduced their sidepull, shorter brake reach
> and closer manufacturing tolerances made sidepulls competitive again (albeit
> not as good as centerpulls in my experience).
>
I realize that you are probably not responding to my post specifically, but I'll emphasize that I don't hold that all brakes are equal or have the same technical power capability. Just that the quality later-vintage single pivot sidepulls that I have used have never given me any trouble for stopping, emergency stopping, steep grade stopping, difficult commuter traffic sudden braking/stopping needs (as opposed to racing use where sudden stopping ability is a lower priority). And that in use I can't detect differences in stopping ability compared to my Mafac centerpulls.
This is probably just a ceiling effect. In other words, for sheer braking power required for sudden stopping, both my sidepulls and centerpulls are fully adequate. So adequate that I cannot experience any capability difference in use. Various things change that ceiling, and no doubt there are others more sensitive than I to differences in hand pressure. But I don't think my experience could be explained by a powerful grip because if that were true I'd be seeing winces when I shake hands with people. I'm pretty sure I have only ordinary hand strength to apply to brake levers, but I'll let you all judge that when I make it to the Rendezvous and we shake hands. Perhaps I have a high ceiling if I got used to using lots of hand pressure after installing Superbe sidepulls in the 70s. Whereas a rider new to cycling and accustomed to recent brake systems would not be willing to use the amount of hand pressure I habitually use (?). I still think I'd notice a big power difference between sidepulls and Mafacs, since I ride them back to back. The difference there is not enough to overcome my ceiling effect.
By the way, as a teenager in the late 70s, to my shame, I replaced the Mafac Competitions on my new Gitane with new Superbe sidepulls because, like many back then, I thought Mafac centerpulls outmoded, and the Superbes were the closest thing to Campagnolo sidepulls I could afford. I think I would have noticed lost significant braking power. So the ceiling effect was in place even with teenage handstrength. (Mafac centerpulls are back on the Gitane, btw.)
Where the ceiling effect disappears for me is 1) with heavier loads so that I seek out more powerful cantilevers on tandems, and 2) for off-road riding where I use powerful cantilevers on (off-topic) mountain bikes. Some early 80/mid 80s mountain bikes came with inadequate side pulls, and I remember how much better cantilevers stopped mtbs. Ceiling effect smashed. Another example of a ceiling effect that disappears for me is that I use drop bars on my mountain bikes, and it's only on mountain bikes where I able to notice the leverage difference between aero and non-aero brake levers.
I've assumed that on a heavily loaded touring bike I'd feel the power
difference between Mafac centerpulls and sidepulls, but, as I
mentioned, I the ceiling effect is still in place with the 20 lbs.
Carradice load I tour with. This would be nice to explore, because if
I had a touring bike built, I'd prefer braze-on Mafac centerpulls over
cantilevers.
> - As Kurt pointed out, if you increase the mechanical advantage, you have to
> put the pads closer to the rim. This is OK if your brake arms always return
> to the same spot. If they move over time, as they do on a sidepull, you'll
> have pads rubbing the rims after a short period of time. By having the
> brakes open further, you increase the amount of time between having to
> re-center the brakes. (Dual pivot brakes, cantilever and centerpulls return
> to the same spot every time.)
>
There may be technical or theoretical reasons why this would be true, but my own practical experience (with the equipment listed in my orignial post) has been the opposite. The vintage single pivot sidepulls (Campagnolo, Superbe, Gran Comp, Modolo/Mavic) seem to never need recentering. Whenever I've had a sidepull pad rub it's been a rim-out-of-true issue, and not a decentered brake caliper problem. Not much touble at all with the Mafac centerpulls I use, but they do require recentering occasionally as they get out of alignment. This may be the result of using the orignal center bolt and nut for the Mafac yoke and these seem to allow movement over time in a way the sidepull bolt/nuts never do. I tighten enough to hold solidly but have felt that to tighten it enough to prevent all motion would overtorque the bolt and nut. There may be a better installment method I should use with a star washer perhaps, but my sidepulls don't move at all even when installed without star washers or other lock washer arrangement.
Cantilever brakes are the most likely brakes in my experience to fail to return to the same spot every time as you say. There are many reasons for this, and I my cantilever brakes ordinarily perform very reliably, but they do require careful set up to make sure each side's spring is properly centered or balanced and that the cable yoke pulls in a centered way. If any of these is neglected in set up or maintenance then cantilevers will not return to the same spot every time. Meanwhile the sidepulls I use, onece centered, return to the same spot every time regarless of neglect. This kind of maintenance is more necessary on (off topic) mountain bike cantilevers that get abused, but is still more necessary on road bike and road tandem cantilevers than for sidepulls (for me).
Note: I don't have any experience with the 50s era sidepulls others have discussed.
Mitch Harris
Little Rock Canyon, Utah, USA
> Jan Heine
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