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M_V
Scilly.Suffolk
^ Gain ratio innit.
Which is a consideration when choosing the length of your cranks. As is pedal strike. As is the stress on your knees.
But there is no need for longer cranks because you have longer legs: your legs describe a circle, not a straight line when pedalling.
If anything, there is an argument for shorter cranks with longer legs to produce a less acute angle at the knee, at the top of the pedal stroke.
5mm longer cranks mean dropping your saddle by 5mm, which means your knee will be 10mm higher at TDC. This increase the amount of shear at the knee, ie your femur will be trying to push over the top of the tibia, more than it would with a shorter crank.
Ouch.