Originally Posted by
bakerjw
Running the math.
With a 20" tire and 46/16 gearing, a BMX at 130 cadence would give about 22.25 mph.
With a 29" tire and 34/17 gearing, a road bike at 130 cadence would give about 22.4 mph. (the compact chain ring on my road bike is 34T)
Except that by 130rpm, most riders power is falling off, a road bike could start at a 34/19 to get better torque at the start and then just move through the cassette up to a 30mph+ terminal speed, while the BMX tops out at 22-25mph. Given fairly equally matched riders, I'm backing the road bike for the win.
If this is a full standing start, I would still opt for SPD pedals over flats to give better foot control and position. If you can go from an extremely slow roll/trackstand, then road cleats.