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)

Of course crank arm length doesn't come into play and I have virtually no knowledge of BMX bike so I cannot make any call on that.
With crank lengths being equal and the road bike set 34 in the front and 17 in the rear, the cadence/speed is almost identical.

With flat pedals on the road bike removing the clipping in delay, I'd have to give the edge to the road bike.

With the crank arm length taken into account, I am certain that there is a road bike ratio that would match the (Torque In)/(Torque Out) ratio.