I wonder about the physics model here. Yes, if you analyze a wheel on its own, spinning up or down in isolation, the outer edge is 4x mass. However, in the real world, the bottom of the wheel is never moving (it's stuck to the road) so you don't have to accelerate it at all; it's 0X mass. At the top, it's moving twice the speed of the bike. Maybe those cancel out? Or maybe there's a more complex relationship.