In the Winter 2008 Bicycle Quarterly, there was an article on the mechanical advantage of brake levers with illustrations that show why a traditional brake lever CANNOT offer the same mechanical advantage when braking from the hoods as a well-designed "aero" brake lever. Basically, with the cable exit direction being parallel to the orientation of the lever, your geometry is tightly constrained. With aero levers, the cable exit is at 90 degrees from the lever, so you can vary the mechanical advantage to your liking.
In the same article, I made the point that even though an aero lever offers better mechanical advantage from the hoods, it still is only about half as good as when you brake from the drops. In the old days, we always put our hands in the drops when we anticipated hard braking - a practice that still is useful today. (For balance, my co-tester Mark argued that only aero levers are safe...)
Jan Heine
Editor
Bicycle Quarterly
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