Be careful to get decent recovery as that is where the true gains come from. Do one hard day and one recovery day, rinse and repeat, but make sure that recovery is beneficial and not just junk. IMO with so little free time, I would stick to the bike for all work, strength and fitness. You will get far more bang from your limited buck that way. If you want to keep the upper body strengthened, then throw some upper body work in right after a bike strength session. Weight training is all well and good if you have the time to do it and the bike together, but from what you said you just don't have that available time right now