I have both the P-09 and aerohead.

I bought the p-09 for the same reasons you did. I ran it all last year and for a few races earlier this year. I bought an aerohead to test it out and based on many positive reports that it has tested fast for a lot of people. I very much prefer the fit of the aerohead over the p-09. The p-09 was a bit awkward fitting as my ears would stick out a bit. I do want to go to ero or aerocamp to test them out but I likely won't be able to swing that until later this year or next year.

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blog

maybe a VWT ; )

I was quite surprised in testing the Aerohead. I think Jim@Ero also said it generally tests the fastest as a safe bet...and it was the P-09 that was the safest bet prior.

I have the p-09 and aerohead and I don't typically run hit but I did a sprint and sweat was pouring down my face on that short bike. The p-09 is far cooler without the visor. I'm giving the aerohead a few more tests in training rides to make sure. If it's still hot like that I'll just go with p-09 without visor

Both are good and both generally test well. The P09 without visor and plug (which is basically as fast and sometimes faster than with) is very cool. I've never felt like I was overheating in it. I've not raced in the AeroHead so I can't speak to that personally.

Just like everything, it is specific to the person testing. The AeroHead is very good, but isn't always the fastest option. Only way to know is to Chung/VE it or test at the velodrome or windtunnel. VE is pretty easy to do, it just take some time and effort.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

I've been using the Aerohead for my last 6 long rides, each in 85 degree+ weather. (2 in the 90s) not once did I feel overheated. The first time I wore it I set PR's on all my segments and even 2 KOM's.

It also feels extremely light, the field of view is incredible. I'm convinced it's the best helmet ever designed.

yes it works.. I have Rx Sunglasses that I have worn under the visor with the Aerohead. The only thing to note though is you have to plan a little in T1. You have to leave the visor off, put the sunglasses on, put the helmet on, then pop the visor on.
Taking it off with the visor is not a problem. It works great.

  
One thing no one mentioned is if you choose a helmet that is 3w slower and you go just as fast you are increasing the amount of internal heat you are generating.

Humans are at the high end ~ 25% efficient on the bike and most of us are going to be ~ 20-22% efficient.

Lower watts to go just as fast = less internal heat produced. Something to ponder

fwiw In the tunnel today I saw a lot of helmets that were either just as fast as the Aerohead at 10yaw but much slower at 0 or faster at 0 but slower at 10. Nothing was faster at both angles

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

thanks i was hoping you would chime in.

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Yellowfin Endurance Coaching and Bike Fits
USAT Level 1, USAC Level 3

+1 I've raced the Aerohead in very hot places and it was just fine

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Are you ready to do an Ultraman? | How I calculate Ironman race fueling | Strength Training for Athletes |

Couple of things...

1. When speaking of the Aerohead, vented or un-vented makes a difference. The vented is much more mortal than the Ultimate (un-vented).
2. The majority of testing we did with the Aerohead during development was all about the visor. Visor after visor after visor was tested. Use the visor! The helmet is designed from the visor back. Interestingly, there was a visor which was clearly better than others, but our test rider (Rohan Dennis) complained of obscured vision, so it wasn't produced (no, you don't get more detail than that).
3. P09 seems to offer the best of all worlds. Pretty good chance its fast on you. Very well vented. Still a great helmet even though it was designed in 2012/13.
4. You really can't go wrong with either.

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Jim Manton / ERO Sports

Thanks Jim - appreciate your input

...and if one tapes over the vents? Does that turn it into an "ultimate" (aerodynamically speaking)?

Just wondering because I just picked one up at a pretty good deal :-)

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http://bikeblather.blogspot.com/

First I thougt that the OP meant with "coolness" which helmet LOOKS cooler. I'm sorry.

Anyway, what temperature is concerned, I have similar experience as this:



I train all summer long now with the aerohead also in temperatures around 90°. No problem with me.
The only problem I have is that the airstream under the visor is such that I already lost two times my left contact lens. Taping off the left hole did not really help. This is not crucial though at least not for me since I can still race without lenses even if they would both pop out.
The magnetic system is amazing, it works great and indeed in T1 you must put on the helmet with the vizor on top and than flip it over, because it is awkward to put on with the vizor. If ever the visor gets intransparent because of condensing (which did not occur to me upto now) or rain you can put it on top during biking.

I find it odd that a large number of folks think that because they personally don't overheat in a given aero helmet, that the conclusion to draw is that no other riders should concern themselves with ventilation or that those that complain of overheating in a given aero helmet are pussies.

Some riders run hot and others don't. Some guys can do an 80 mile ride climbing in hot weather on one small water bottle. Other guys will do that same ride and go through six bottles.

Some riders can effectively run 145mm cranks. For others, that's just way too short.

Some riders can ride a wooden plank for a saddle. For others, then need a split nose or cutout.

Some riders need a short & tall frame. Others need long & low.

Different riders, are... well, different. So if overheating/ventilation isn't an issue for you, congratulations (I mean that sincerely), that's one less thing you have to worry about and your helmet options are limited virtually by only aerodynamics and price.

But if you've ever ridden an aero helmet, had sweat pouring down your forehead during the race and after pulled it off and your head and hair look like you just exited a swimming pool, you should not feel stupid or ashamed for taking ventilation into account when selecting the helmet that is best for you.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Agree. It's different for everybody. I've tried the aerohead and for me it's warm. I raced a sprint triathlon and sweat was pouring down my face. That was a 13 mile bike.

Haven't tested that yet, so don't know. I'll work on trying to get some numbers.

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Jim Manton / ERO Sports

Any results?