Thanks for the great thread it's inspired me to do my first 200km fixed ride.I did it on a 72 inch gear on a very flat course,the only gradiants were over railway bridges ect...The first 100km was into a headwind,nothing major about 10-15mph winds and I tucked myself behind a good strong bunch of riders.The hardest bit for me was trying to keep up with my friend.He put his bike into the big ring and rode at about evens for 65kms,I found this very tiring spining away at over 100rpm.I got out off the saddle at any excuse slight inclines,road juctions ect....No sore bum,but my knees ached like mad the next day.To be honest,I don't think it would have been any easier on my geared bike,apart maybee from the 65km stretch with the tailwind.