My old helmet is a Bell. As I mentioned, no real thought went into that purchase. I was in a local shop a few days ago and tried on Giro, Garneau and Giant. The Garneau fit well, but I didn't like the color. I came home with a Giant. I found the buckles kind of annoying, but figured the straps were new and stiff, and I just wasn't used to it yet. Then I compared it to the Bell and found the older one has thinner straps, and it's one continuous strap that is thread through the helmet. This allows it to be pulled to one side or the other to move the buckles to a more comfortable position. I also found that the Giant seems a little rounder, and I can slip my finger between the helmet and the side of my head (more so than with the Bell).

I was in another store today that had a Bell and as soon as I put it on, I could feel the difference. It was a basic, no frills model, but with only a few vents on either side, none down the middle. My old one doesn't have the center vents, either. That's why I ask. Would I have even noticed? One has lots of small vents, the other has fewer, but larger vents.