You armchair physicists are confused if you are comparing crankshaft torque on a motorcycle with crank torque on a bike.
IF you wanted to make a comparison (engineering by analogy is an awfully imprecise science!), you should compare belt tension on the bicycle vs. belt tension on the moto. Ignoring preload, belt tension on the motorcycle will come from crankshaft torque multiplied by transmission gear reduction and divided by output pulley radius. But it seems like a totally pointless comparison.