Originally Posted by
electrik
The increase in radius is from 559 to 622, and the torque curve is linear - about 10% decrease in leverage all else the same.
26" wheel w/ 160mm rotor ~ 700c wheel w/ 176mm rotor. Of course, if you're locking up the wheel on the 26" bicycle already then you're probably fine.
The 700c equiv might even be slightly less considering the braking actually happens maybe 5mm out from the centre of the rotor.
As an estimate, I'd say the drops with 2nd gen ergos give about 180% of the mechanical advantage lever-to-caliper of the tops. 3rd gen the difference is less because the pivots are higher (better design IMO)
To add an empirical datapoint to the endo debate, a few years ago I was cycling on my racing bike downhill on a country road in Wales, going pretty fast (24mph perhaps) when a van comes round the corner at a stupid speed (40mph maybe). I slam brakes and somehow get down the side. Brakes are Campy Record dual pivots from about 2002, bike is light.
Now, the rear wheel lifted a lot but I didn't go over. I'd say maybe 40cm. But before this point of it lifting I could tell it was off the ground and had started to lessen the braking. I then continued to brake with the wheel at a constant height. The modulation was there to do this.
Very, very near miss. Had twigs stuck in my levers and wheels from brushing the bush to get through. Could have been very nasty.
So... in the general case, how do cyclists go over the bars? My thinking is they don't brace their bodies properly - eg, their arms don't push back hard enough on the handlebars. Then they move forwards relative to the bike, their knees hit the handlebars and they tip the bike over.
The only time I have gone OTP backs this up. I was racing with my old club in Wales. At the end of the ride tried to stop at the side of the road. Hidden curb, all my weight on front wheel, already starting to dismount, knee hits bar, front wheel clamped and over I go. Later that day someone else punctured on the same bit of road.