Heavy cardio and maintaining strength

[cbloom]

So, the question is how to maintain upper body muscles while doing really heavy cardio.

The specifics : I've started doing some semi-serious cycling, about 200 miles a week, and I'm not really doing heavy upper body work to balance it and I'm worried that I'm going to be burning upper body muscle. I'm okay with not adding any upper body muscle but I'd like to not lose it.

I have been doing some decent pullup and pushup work every few days, but dunno if that is enough. I'm also curious about the ideal training methods to let me build up my cycling without hurting my physique too much. Like, should I try to alternate cycling and weightlifting days, or is it enough to just do a little bit of weights. Is there any merit to doing something like dropping and doing pushups right before or after or during a ride?

ps. I know that a serious cyclist would muscle up in the off season, and then burn it off during race season