Ride, Wrench, Swap, Race
Join Date: Jan 2010
Location: Northern California
Posts: 9,194
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
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The 4mm change in pad height effects about a 10% reduction in caliper braking leverage when switching to 700c, one more detail to perhaps ponder.
It's just the opposite though if the bike has canti's, where the leverage improvement can be quite a bit more than even 20%, and where the pad-dive angle (of pad trajectory) reduces pad clearance at the tire's sidewalls while also tending to drive the pad off of the edge of the rim (toward the spokes). So setup becomes more demanding, especially when the pivot post spacing is relatively wide and/or when the rim is relatively narrow (and narrow relative to the tire width), and when the rim's braking tracks are on the short side. I used very wide Module-4 700c rims with ~26mm tires on my Trek 720, and the braking power is pretty fierce now.