Considering the overwhelming majority of this forum are weekend warriors and club riders, i don't understand the aversion to weights. If you're trying to break into the top CATs or something and need the extra edge then fine, but for everyone else, the puny upper body might make you slightly faster on Wednesday nights, but it's a liability the rest of the time. Besides, having some definition in the upper body is not going to slow you down that much. You really need to top out elsewhere before you need to start worrying about cutting upper body muscles for a better power/weight ratio, and i would venture a guess that most of us here haven't done that.

I lift twice a week, hitting every major muscle group and using free weights where i can to activate some of the stabilizing muscles. Then again, i'm primarily a triathlete and an upper body is beneficial, plus i find a moderate lifting routine keeps injuries away.