I usually walk if the process of carrying the bike up and down my stairs and locking and unlocking it at my destination takes longer than the actual ride to wherever I'm going. So that means I usually walk to anyplace that I can reach in 10-15 minutes on foot. I've lived within walking distance of a grocery store in my last two apartments, and I love it. So convenient. It also keeps me from impulse shopping, because everything I buy I have to schlep home. If I have something bulky to buy, I take along my handcart and lock it to the bike rack while I'm inside the store.