Quoth Jason Hodges:
> I'm going custom for my next bike and I need some considered opinion on the following:
>
> What is the optimum distance between the dropout centers and the brake bridge when using "long
> reach" (57mm) dual pivot brakes (Shimano R600) and 700C wheels?
>
> Does simply adding 622mm (bead diameter) and 57mm (reach) give the correct answer?
You're on the right track, but not quite right. The bead diameter does generally correspond
pretty closely to the middle of the brake track on the rim, but it's the _radius_ you want, not
the diameter.
311 + 57 = 368, which would be the _maximum_, center to center. Since the caliper actually sticks
out a bit from the frame/fork, you need to allow a small fudge factor.
The "57 mm" calipers actually have a range of adjustment from 47-57 mm. If you want to
maximize fender/tire (mudguard/tyre for our British friends) clearance, you want the bridge as
high as possible.
If you want maximum possible braking force, you might go a bit lower. Generally, having the shoes
adjusted higher up in the arms increases braking force, but modern dual pivots have so much
mechanical advantage that there's no practical benefit to this.
Sheldon "Stop!" Brown +-----------------------------------------------+
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| Tsiolkovsky |
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