Feel vs function
Too little mechanical advantage leads to low braking force. The feel on the lever will be firm, but this feeling is misleading. When trying to brake hard with such brakes, the force applied to the brakes will be relatively small, inadequate for effective stopping.
Too much mechanical advantage leads to a mushy, spongy feeling at the lever, since great force squishes both pads and cable housing. Braking force would have been great if the pads would touch and rub the rim/brake disc rotor all the time. Since pads are always at least 1 mm away from the braking surface, too much mechanical advantage results in lever being pulled all the way to the bars and brake pads just reaching the rim, not applying any force, or not even reaching the rim.
This is why mechanical advantage needs to be balanced. The amount of cable pulled by the lever needs to match the movement of brake pads. If the brake lever pulls 10 mm of cable, the brake pads should move about 5 mm, which makes for about 2:1 mechanical advantage.
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I just cut & pasted all that jibber jabber because yesterday I swapped out the handlebar, brake levers, cables and housing on a rain bike and took it for a ride. Testing the brakes and in the back of my mind I could hear Steve Maluk scolding me for halfassing a bike build by using V-brake levers on canti brakes because they were there, because I was lazy, because I didn't want to dig deeper in the parts bins for the proper levers.
But here & now all I have to do is switch the cute little doohickey in the levers from V to canti, for the proper feel and function. Cheers to you Steve. Cheers to good old rim brakes and XT levers that go both ways.
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