I used to ride 72" fixed all the time and once a year took the bike up Streatley Hill, just to prove to myself that it was there and that I could still do it. Then the bike broke and a break of several years from the above ensued.......until this morning that is, when I took my new fixie (42x16) up. 'what's the worst that can happen (apart from intense lactate burn, blurred vision and extreme nausea... ahem...)?'.........yeah and the rest!