if you want to develop strong legs and a good base of off season training.
get a fixed for winter training...
I have been riding my lovely fixed around for the last six months, and I got on my tri-bike at the weekend and flew like the wind! the base training has really paid off...
I still feel that varable gears are only for people over forty-five.
Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer?
We are getting soft...As for me, give me a fixed gear!
--Henri Desgrange, L'Équipe article of 1902 http://www.sheldonbrown.com/fixed.html
cheap to build and will save you more seconds of your 40k time that £1000s of gucci extras for yer road bike!!!