wont this way make chain aligment and sprocket aligment perfect and sturdy?

[cloakedvillain]

I think you can get away with a 40tooth sprocket if you run/use a 220mm or bigger rotor.

Those are hard to come by. Since hubs brakes are being used the rear wheel could be dropped to a 20 inch so your reduction is is divided less than it would be with a larger wheel.

The first two are top speed comparisons and the last is what Mr. impulserocket is running. Or close enough anyway.