Yeh 80lbs, kill a man (or girlfriend) at 200 yards.
Just fitted a 12-27 to my madone to help me get up the hills.
I did one 10 mile time trial and just scraped in under 29 minutes.
I tell my cycling buddies this: next time you're on a 6 or 8 percent uphill grade, pedal up to 14.5 mph. Get used to the effort level. Then imagine holding that speed on the uphill grade for 9.5 miles. That's a Lance Armstrong time trial.