One thing no one has really touched on is that if you are riding into a head wind your air speed is you actual speed plus the wind speed. So say your doing 10 mph into a 20mph head wind...the air is going past your bike at 30 mph and those wheels (or anything else aero you are doing) are helping.

I'm no pro...or racer. I average 17-18 mph on 30-40 mile solo rides. For a time I had Soul S4.0 40mm alloy clinchers and for sure I felt a difference. I gave them to my father who races...he says he can tell the difference.

I just picked up a set of Reynolds DV3K from Bonktown for $865 shipped and can't wait to ride them.