Originally Posted by Hermes

When I did my aero testing at Velo Sports Center with ERO, I tested three other helmets against the Selector and it was equal to one other helmet and the other two were worse, so I did not see a reason for a change. Getting the right helmet is really tricky in that promotional materials and technical specs of aero helmets may not work in practice for the rider. So one really has to test.

The answer to the question is I hate the Selector but it is fast. I would buy a different helmet in a heartbeat if I knew it was faster than the Giro. Notwithstanding that, heat dissipation is important and if ones head gets too hot, the internal body temperature rises and derates the engine. For pursuit that is over in a couple of minutes and the 500 meter time trial, heat is not a problem. For an hour record or a long time trial, heat rejection may be a factor.