Originally Posted by
Darth Lefty
From another thread...
This got me thinking more generally. Why do bikes always seem to have the same brake front and rear?
Because fewer types of parts to make means higher profits, and assembling brakes which differ only in center bolt length, nut length, and pad holder mounting direction means fewer parts than two totally different brakes.
If you were an engineer looking to save ounces from one component to strengthen another, why would you put, essentially, two front brakes on the bike?
In response to Shimano's lightened DuraAce calipers for the 2001 model year Campagnolo introduced a "differential" brake option with dual pivot front and single pivot rear saving 40g a pair (380->340g a pair for Chorus, 348->308g for Record which is identical except some of the hardware is titanium where it's steel for Chorus).
The rear single-pivot unit is on the left and front dual-pivot right.
In the unlikely event that you're a racer, competitive, built for climbing (two pounds per inch suggests the right morphology which is 140 pounds at 5'10"), and racing to an up-hill finish in the mountains the 0.05% speed increase means a 2 second advantage for each hour you spend off the front (assuming a 140 pound rider atop a bike approaching the 15 pound UCI minimum). The difference is less for heavier rider + bike combinations.
The single pivot option offers a bit more tire clearance and the 2001-2006 Chorus/Record hidden hardware single pivot rear looks great, although outside a very narrow range of competitive situations the only substantial benefit is marketing.
Supposedly the rear is easier to modulate because the lever travels farther although I haven't found that to be significant. It does take a harder squeeze to lock up.
Dual pivot front and rear are also offered at the same component levels, with some people preferring that option for the lower lever effort in back.