Your concerns are real, and I would advise you to consult your surgeon first before undertaking such a rigorous cycling regiment. I paid a severe price for excessive activety before being completely healed (2 additional surgeries). It is better to be cautious for the first 6 months to 1 year.
Diagnosed at age 60
PSA went from 2.2 to 3.8 in 14 months
2 of 14 cores positive at 10%
Gleason 6(3+3), negative DRE, neg. margins
DaVinci surgery on 02/23/06
Last PSA 08/26/07 @ 18 months "0"