Review on Gore Wear Windproof Windstopper Turtleneck: Ultimate Protection against Wind and Cold by Dred Swindler

This is an absolute must if you ride on spring and autumn days when temperatures are in the 40s. It breathes from behind and protects against wind from the front. A high neck is also important. I'm 5ft 11" 170lbs and I have both a medium and large, the large is a bit big with long sleeves and the medium fits snug but is difficult to take off afterwards. In general, if you think you'll end up somewhere in between, go a size down rather than a size up, as the tighter the better the aerodynamics. And yes, I would think the medium would be suitable for racing, having raced in Chicago in early spring and letting go of a bulky, heavy coat. If it's over 50 and it's sunny outside, it's probably overkill and you can get a thinner version with a regular neck.