As a BMX'er....

I could be a bit wrong on this. But with BMX in the first Olympics I believe Jason Richardson was peaking at 2,328 watts But I don't know how to work out the torque because I don't know the gear ratio. With the older style BMX freewheels the chain always snaps first. I've taken part vintage Suntour bmx and road bike freewheels and found that the pawls etc were quite similar. In 3rd world countries many have bicycle powered carts and haul huge amounts of weight.

But modern BMX 9t cassettes seem to brake often. The pawls chip or wear out, and the springs seem to break. They tried to go with a 8t and the torque was sheering / breaking the teeth off them. So I can't help but think a 18t is going to be a little stronger then a 16t.