Lee Berg wrote:
>I have noticed a number of '70s bikes, whose frames appear to have been
>made for short reach calipers, sporting normal reach calipers with pad
>holders in the tops of the slots. Were normal reach calipers installed
>due to some desired mechanical property of this arrangement?... or due
>to a some extended shortage of short reach calipers?... or was it just a
>fashion of the time?... Or...???
Short reach calipers generally have a reach range of 39-49. Long reach is usually 47-57. (Talk of "normal" reach is likely to be confusing, and I'd urge everybody to purge this ambiguous term from their vocabulary.)
A caliper brake has its greatest mechanical advantage when the pads are high up the arms, close to the pivot. Back when long reach was the "norm" a conscientious frame builder building a high performance bike would locate the bridge and crown to maximize the braking mechanical advantage. Especially, the old Campag single pivots had such poor braking that this was a very nice touch.
You may also see this on bikes made to work with both 630 mm (27 inch) clinchers and 622 (700c) tubulars. When the larger wheels were installed, the shoes should be near the tops of the slots.
Sheldon "Stop!" Brown
Newtonville, Massachusetts
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