Certainly when both brakes are used in a panic stop there is a huge difference in desired leverage between front and rear brakes. The unequal calipers do a bit to remedy the resulting tendency toward rear wheel lockup and also give the rear shoes greater travel and thus rim clearance, useful when considering rear wheel's tendency to get out of true and rub the pads. Further, an increase in rear brake bridge height comes at no cost and can improve fender clearance, but lengthening fork blades increases their weight as well as the bending stresses, so further weight then needs to be added to maintain strength. Only on bikes with overall brake power deficiencies might I prefer an identical reach, and often the rear cable's more circuitous travels cuts rear brake power. Note that Campagnolo's modern take on unequal "brake reach" is to make the rear calipers with single pivot, reduced leverage and lower weight.
David Snyder Auburn, CA usa
> Gentlemen and ladies,
> I'm risking your scorn by asking what may be an old chestnut of a
> question, but I have tried the archives and can't find an answer.
>
> We've noticed a design "feature" on many frames from many countries and
> built over several decades: the rear brake reach is longer than the front.
> It seems most common on older ('60s) frames where centerpull brakes are
> spec'd, but certainly not exclusive to them.
> What's the purpose (or purposes) of it?
> And if it was a good idea back in the 1950s to early 1980s, why not now
> (other than the obvious, economy and simplified manufacturing)?
>
> Thanks in advance (for any info and for your indulgence)
> Alan Goldsworthy
> SF, CA, USA