Folding Cycles and their Rider Weight Limits

Not necessary with fixed wheel due to the flywheel effect that push the pedal round.

With a smaller wheel - less flywheel effect thus required more power input.
Not true, in fact its the opposite, i.e. the smaller, lighter wheel requires less energy to accelerate (also due to less drag from air resistance), whether from rest or from a medium speed to a higher speed. However it is true that the smaller, lighter wheel loses speed again more quickly due to lack of flywheel effect, e.g. when you start climbing a hill, or when braking. If flywheel effect was such an advantage you would all be running the heaviest wheelsets you could build, but something tells me that is not the case...