I've just finished (abt 5 days ago) a 208 Mile Bike Marathon and while I was really happy to have made this goal, I have strained some muscles in my legs - namely have some Patellofemoral and ITB pain (my dad is an ex-PT, so this helped). I was advised to stay off the bike for a while until it heals - problem is, I've another Century ride coming up in a month and I'm one of those people who does not deal with "Downtime" very well.

Any ideas on Cardio I can do so I don't gain weight? I've just been at the gym doing upper body weights.