John,
Hi, another 'convert' from stw site I see!!! (only joking!)
Do you mean roadie biking or mtb's.. You should ahve plenty of time to get run fit for may... What sort of running (lengths and days are you doing now...?)
I normally do 2 night rides a week on week days, 2-3 runs on the other left over days, and then one day long bike and one day long run on the w/e...
pretty much I'd say for a 1/2 you can fairly mix and match how you like...