One speed vs Two speed gearboxes

[Ekcrbe]

Originally Posted by Jared

I expected it to be more, which is why I did the math. I wonder how much the gears/chain/shafts contribute to the rotational inertia.

Those should be very little. The squared term in the rotational inertia of axially symmetrical objects is the radius, and almost nothing else in the drive system comes close to the wheels in radius. The only examples I can come up with are the transmissions we made in 2012 and 2013. The first reduction was done with Gates belts instead of gears, and the large pulleys were about 4" in diameter. They were spinning faster than the wheels, so they needed more energy put in to get going than if they were further along in the reduction sequence, but they weren't that heavy. They were aluminum and pretty well lightened, so I don't think they mattered that much.