During warmer weather I commute on my road bike and have a 31 mile r/t. I don't need to carry anything except my wallet, keys and phone so all that fits into a small frame pack along with a spare tube and a co2 cartridge. During winter and other inclimate weather I ride my old road bike with fenders but that route is only 24 miles r/t.

I tend to hammer the whole way so a road bike makes the most sense for me. For me the road bike is the most efficient way to go.