Originally Posted by
Zoroman
So a double crank will require a way to shift (i.e., gearing), thus you introduce a derailleur ....Isn't that a multi-geared bike then with at least one half of the complications of the conventional multispeed bike with a front derailleur and a rear derailer?
No, it's just a double crank and a chain guide (pulley wheel), nothing else requried. It's like your 2 cog setup but without having to remove the wheel to switch between them, no extra tools, no turning screws, no derailleurs, no spliting the chain