I ride a bike that weights 35 pounds with all the stuff i have-- fenders, pump, lock, tool kit. I have an upright riding position and i don't go really fast-- gearing is 46:22 which is low.

When does weight become more important than riding position? For example, I read someplace that after a certain speed 75% of your energy is expended overcoming wind resistance. Not sure if I remembered that right or not. But I'm cruising along at 10-12 mph on my bike in an upright position with low gears. Just how much would it benefit me to replace my heavy metal fram with an aluminum one and reduce my total weight from 35 pounds to around 25-27?

I do think dropping 10 pounds off the bike would make it easier to move in and out of my apartment and manhandle it etc, etc.