To your last question, in 1970 I received a Raleigh Record for my birthday which had Altenberger Synchron calipers. These worked better (more power, less flex at the lever) than the center-pull brakes I've used on similar bikes of that era, seemingly due in part to the lack of a cable hanger and the flex therein. In fact, I later replaced the front caliper on that bike with a generic, Japanese, centerpull caliper, and so was able to make a direct comparison at the same reach dimension (tho the Weinmann front caliper on my Grand Sports model uses the more-rigid stem extension as a hanger and leaves nothing to be desired).
One detriment of dual-pivot calipers is their inability to float freely about the center-bolt in the event a broken spoke throws the rim out of plane. A normal sidepull caliper is comparatively unnoticeable as far as it's effect on rubbing friction against a bent rim. In the days of generous tire clearances on racing bikes, such an advantage of the single-pivot sidepull could make the difference between winning and, uh, the other outcome. Dual-pivot calipers would also seem to be more of a engineering task to design, and likely even more difficult to design to the same weight (not to mention price) as single pivot calipers. The Synchrons also used a synchronizing rubbing block between the arms, whereas current dual-pivots make contact between the arms only in the rest position (where the centering screw contacts the other arm).
David Snyder after bedtime in Auburn, CA usa
----- Original Message ----- >
> ...- was the idea of a dual pivot patented?
> - why did they take such a long time to catch on ?
> - why were the first 3 instances of dual pivots so very very similar ?
> - was the Raleigh Super Tourer (1974) the first production bike
> to use them ?
>
> - Don Gillies
> San Diego, CA, USA