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Most fitting "systems" specify that some part of your knee be directly over the pedal axle at some alignment of the crank, usually with the pedal forward and the crank horizontal. This is pure nonsense. Imagine two riders, almost identical, but one rider's knees are 1 inch lower than the other's. In other words, the thigh bones of one rider are 1 inch longer than the other, and his lower legs are 1 inch shorter. Everything else about these two riders is identical, including overall height, torso length, arm length and weight. If you position the saddle such that the knee is directly over the pedal axle, the rider with the shorter thighs must have his saddle a little under 1 inch further forward of the other rider. It would be exactly 1 inch if his thigh was horizontal at that pedal position, which it isn't likely to be.

But with the saddle positioned forward, the rider with shorter thighs now has more weight that must be supported by his arms, all because of this arbitrary rule about having your knee over the pedal axle. This makes no sense. What matters is your weight distribution fore and aft, and that's determined by the fore-aft position of the saddle relative to the cranks.

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