Originally Posted by DannoXYZ
Ok, I was a little hasty. In general:
1-5 reps: power & strength
8-12 reps: muscle-growth and hypertrophy
15+ reps: muscular endurance
Still a little hasty. The ACSM warns that very heavy weights ("1-5 reps") should only be used by advanced lifters. The OP probably is a beginner or intermediate, as are most exercisers.
With such heavy weights, even a slight deviation from good form could cause serious injuries. Timing and proper recovery are important also. Even the risk of just dropping such a heavy weight is considerable. You probably need a trainer to go there, or lots of personal knowledge and experience plus a reliable spotter/observer. Finally, a heavy regimen like 1 rep will probably leave your muscles too tired to do much cycling that day.
Again, the ACSM recommends 6-12 reps for both strength and hypertrophy, for beginning and intermediate lifters.