I own three of these helmets and they fit very well. Light enough to not even notice you're wearing any helmet at all. I highly recommend this helmet for road biking, though I haven't used it in a tri yet. Will probably go with the Giro Advantage 2 for that.

This is one nicly vented helmet. I can feel the air being sucked out the back. It's very light compared to my old Trek and fits way better. The adjuster is so fine that I could probably wear it without the straps (but wouldn't). It's such a nice lid that I don't use it for my tri's cause I'm afraid it'll get stolen. I use the Trek until I can find a good cheeper helmet for the races.