I have an ongoing argument with a co-worker. We are both active milatary and primarily runners, but have both taken up road biking recently as a change. He insists that it is harder to ride into a 15 mph headwind than it is to run into it. I think he is just a better runner than rider and therefore it "feels" harder. I think that aero and mechanical advantage a bike offers has to make riding into a 15 mph wind easier than running into it. You Tri guys seem like the perfect bunch to answer the question...of course it could just be an individual thing I guess.