reply to PISTONHEAD......speed is everything when riding. the average cyclist will ride 13 miles in one hour riding on flat ground. single, no drafting.
someone in really good aerobic shape can ride a century run (100) miles in about 5 hours.
the average 40 km (25mile) time trial, no drafting, for an average racer should take less than an hour.
how fast are you riding to get wiped out after 3 hours? if you're riding 75/85 miles, killing yourself, that's good for interval/speed training, but doesn't help if you do it every time you get on the bike. why not slow down and ride 6 or 7 hours, building your aerobic capability and enjoying the ride.
don't mean to lecture. riding was my whole life for a few years, racing the most fun i'd ever had.....till i was run over by a drunk driver, ending my riding/racing days. sorry, i'm going to cry now.