Originally Posted by
bloodfont
I understand your sarcasm
but you need a springloaded chain tensioner to use and FD and that is not possible on a fixed gear, it'll rip it of.
Initialy I thought you gave me a link to the Schlumpf 2 speed crankset, which is an option, but expensive
The chain tension that will rip off a derailleur if used with a fixed drive train will also rip off that little chain tensioner you linked to. If you want a variable gear drive train with the convienece of a single/fixed, either get an internally geared hub or crank. Otherwise, just ride it fixed/single. If neither of those work out for you, get a bike with a derailleur drive train.
I don't understand why people are always trying to reinvent the wheel with a single/fixed drive train. The whole point of it is its simplicity and reliability.