Yea, What Koffee said. Might take a while to get specific again. but like the saying goes, if you want to get better at biking, ride alot. Swimming if done well, can really keep you in good cardio shape but without biking you will lose some speed. and of course, your tushy won't be ready for the 2+ hrs /ride right away anyway. You'll come back quickly though. Good luck with school.
Barley