lennyparis

Have an older Giro helmet and want a more aero helmet
Tried Specialized Evade but my round head does not fit with its oval profile
any other helmet suggestions?

kookie

I went from a Giro Ionos to the Kask Protone. No complaints so far.

Xherion

Bontrager Ballista ranks very well in terms of cooling and aerodynamics.

KantoBoy

Coming from a Giro Air Attack here the ventilation is much improved (although if you live in a cold country like myself that might serve you better).

I'm obviously believing whatever Trek's marketing tells me in terms of aerodynamics. I did have a fast-ish group ride earlier and it felt good. I don't have a wind-tunnel to test their claims unfortunately.

My only gripe I have with it is that the locking mechanism/fit system I feel is a bit flimsy. I like the mechanism on my Air Attack better with a smaller dial.

If money wasn't an object I would've gotten the Protone. It's probably the best fitting helmet I've tried. It just felt right as soon as I tried it on.

The only thing that didn't feel right was the price.

GlennR

If you like the fit of the Giro, try a Giro Synthe. It's aero and has great ventilation.

RNAV

I have a Ballista and like it . . . however, I'm now in the market for a second better-ventilating helmet. I'm comfortable in the Ballista up to about 90F. Above that, it just doesn't flow enough air to prevent over-heating. As long as you're moving, you're generally ok. But if you have to stop (stop light, waiting on other riders in your group, etc.), it's darn near unbearable above 90F. Of course, the fact that mine is black probably doesn't help. Bottom line, it doesn't vent jack when you're not moving.

Xherion

That is pretty much a common issue with all aero helmets. The cooling comes from the flow of air from the front and expelling it through the back. Not so much for climbing or slow movement where the heat needs to dissipate from the top. Those vents at the top of a typical non-aero helmet are covered up in an aero helmet to make them more aero.

There are some "aero" helmets that might fare better than the Ballista, but they generally don't perform nearly as well in terms of aerodynamics, like the Protone or Synthe. IMO above some temperature threshold, an aero lid is generally not practical to use.

K.Katso

^this. The Kask Protone is also a good option if it fits you. You won't be disappointed with either

mpath

Let's keep in mind "aero" in this context, is relative; its benefits/advantages to the great many of us is marginal. Ventilation, OTOH, is noticeable from helmet to helmet.

DrIsotope

I really do love my Bollé The One, which is both an aero helmet and not an aero helmet. It has two hard inserts that cover all but three of the vents. On cooler days I'll wear it with just the front cover, and on hot days, no covers. So in spirit of full disclosure, I didn't buy mine with the covers because I wanted superaerofast, I bought them because last winter I almost froze my hairless head off. But it does work admirably as an aero helmet.

For Fredly super-bonuses, also has a winter liner, removable MTB-style visor, and optional blinky taillight.

RShantz

I had one of the Ballista's and returned it under Bontrager's policy. I climb a lot and the heat was excessive to me. Even on the flats it only felt like I was getting air in 2 spots on top of my head - the rest was like an oven.

Drew Eckhardt 

Louis Garneau Course. Tests OK, has good ventilation, looks like a normal helmet.