Join Date: Mar 2006
Location: Vancouver, Canada
Bikes: Rodriguez Shiftless street fixie with S&S couplers, Kuwahara tandem, Trek carbon, Dolan track
Track racing is all about leg speed. The main reason you want a shorter crank (regardless of leg length) is that it gives you a slight advantage. With a shorter crank, for the same crank rpm, although your feet are travelling at the same angular velocity as a longer crank, they are actually travelling at a slower linear velocity, and they are not travelling as far. (The closer you are to the center of the circle, the slower the linear velocity for a given angular velocity.) If you increase the linear velocity of your pedals, you will be cranking at a higher angular velocity; ie, more rpms, thus the bike goes faster. In other words, you can crank higher rpms with a shorter crank, a definite advantage if you've only got one gear to work with.
The fact that you can ride slower on a steep track without hitting the pedal is just gravy, and isn't really a concern for most North American riders unless they live near Burnaby, Portland, LA, Blaine, etc. or they like to travel.
One of the tallest 6-day pros was Peter Post. He won the second highest number of 6-days in his career (second only to Patrick Sercu). He's a big guy, around 6'4", as I recall, and he used a long crank by pro 6-day standards: 167.5. Unless you're riding pursuits, I figure 165 will do for most riders. I'm 6'1" (186 cm) and I use 165s.