I just converted my Peugeot carbon bike to a fixie. No one wanted to buy one of the first carbon fiber bikes brought into America, so I thought what the hell; try something different.
It cost me nothing to do it, and the bike is now much lighter w/o gears and derailleurs. It'd be even lighter if I were to replace the old-school Mavic 36-spoke wheels.
It's my first time with that type of bicycle. I left the brakes as I haven't yet figured out how to skip skid to a stop (or whatever it's called in the fixie world).