I have not worn the Quartz on my mtn bike yet, but I have used it quite a bit with beginner road rides. ( groups riding quite often below 10 MPH) I find the helmet cool and comfortable, and like others have mentioned... more expensive helmets are cooler and often times more comfortable. Although of course the most important feature is FIT.

When I switched the helmet line at the shop, I was coming from a Giro Pnemo... which I loved. Although that was very short lived when I bought a Louis Garneau... it was much cooler and fit better. But of course, we all have different head shapes, so find something that fits you!