The Giro Aeon is the best bike helmet on the market today because of its effective ventilation, ultra-low weight and smart style. The Louis Garneau Quartz (Est. $140) is also lightweight with great ventilation, but professional reviewers and casual users agree the 50-gram difference in weight puts the Aeon miles ahead. Factor in Aeon's 24 channel-style air vents, and it's clear why reviewers including editors at CompetitiveCyclist.com say the Aeon "vents like a champ." The vents run lengthwise down the body of the helmet, funneling cooling air over the crown of the head and pushing it out the back of the helmet.
Meanwhile, the Bontrager Specter (Est. $140) is another, cheaper alternative to the Aeon. According to the editors at CompetitiveCyclist.com, it doesn't have the same "fabulous" style. But it's still well made and comfortable, just a step down in ventilation, weight and style.
The Lazer Helium (Est. $240) is another top-shelf helmet to consider. This helmet's unique one-finger adjustment system earns a better rating from CompetitiveCyclist.com editors than the Aeon's system. So, cyclists who want to adjust and readjust their helmets mid-pedal may want to give the Helium a try. However, the Helium weighs 130 grams more than the Aeon, is not much cheaper, and is only "reasonably cool," as BikeRadar.com reviewer James Huang puts it.
Finally, the Bell Gage (Est. $190) is only 22 grams heavier than the Aeon. The Gage is comfortable and especially accommodating for larger head sizes, reviewers say. Riders who feel that the Aeon's fit is a bit too snug would do well to try the Gage on for size as a comparable lightweight, high-performance helmet.