Aero Helmet Data

Hello from Colorado, where my car is buried under a foot of snow, and my bike is married to the trainer…

I am researching the various aero helmets for use in a half ironman later this year. Given the 56 mile ride, it figures that going with one of the more goony designs might be worth it. There seem to be loads of good options to pick from, here are “a few” I am considering: Giro Aerohead, Louis Garneau P-09, Kask Mistral, Specialized S-Works TT, Smith Podium TT, Kask Bambino Pro TT, Oakley Aro 7, Giro vanquish, Rudy Project Wing57.

The issue(s): 1) I don’t know anywhere that sells these, so that I could try them on for fit and comfort, and 2) while you can Google reviews and “best of” for these helmets, virtually none of these articles answer the very question that these products aim to solve: which one is the most aerodynamic, or the fastest?

Question: does any manufacturer or third part publish their wind tunnel data on aero helmets, or is there some side-by-side comparison I can find that would allow me to make an informed decision? Sort of thinking like a that would show the watts savings/loss, but for aero helmets and gear.

I won’t discount objective safety data, and features such as MIPS which I believe are very important, but for this discussion, I’m really just interested in what helmet is the fastest.


Aero helmets are VERY individual…what is fast for one rider may be dog-ass slow for another. A rider’s position and posture can change everything.

That said, some helmets tend to test fast regularly…the Giro Aerohead is one of them. The LG P-09 is another. Another option is the Giro Advantage 2…definitely an older design, but still fast.

I think the POC Cerebellum also tends to perform OK, but not as consistently as the ones above.

Another general rule of thumb is that the the really short-tail lids (Oakley, Kask, etc) tend to only test well if your head is below your shoulders or you can “turtle” extremely well.

But lots of people will tell you “oh, this is helmet is great” based on what rhey ride, but it may not be right for you.

One final thought - if you are moving from a general road lid, any helmet noted above will be a significant improvement. Whether it will be the “best” is difficult to answer.

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I saw only 0.5W gain with the P09 over ballista on a test I just did last weekend.

Details of the test and wattage determination are in another thread in last post. About 20 mins round trip, pretty carefully controlled intervals on flat rail trail with no disruptions. Disappointing as I expected to see at least a 5W gain. Maybe the ballista is just a really great helmet… I should try against an older non aero road helmet from years ago.


Allow me to totally disregard your topic:

I am using the S Works Evade w/ANGI

And the air noise around my ears is vastly reduced

Does anyone have first hand experience or opinion of the POC Ventral Air SPIN helmet? It appears to be aero as well as offer enhanced ventilation. It has it’s own version of “MIPS” called SPIN (Shearing Pad Inside) so that makes it a feature to consider.

It really is highly individual. No test in the wind tunnel will give you a helpful result, unless you are sitting in the wind tunnel in your aero position.
First of all I would consider the temperature of the race.
At IM Frankfurt last year, I used the Giro Vanquish. It had 42C and I needed as much ventilation as I could get.
Next you could order some different models. Put your bike on the trainer, go into your aero position and let someone make photos of your front and your side.
Front is easy: the smaller your overall size is, the more aerodynamic you probably are. Side is a bit more complicated: If your head is high and there is a huge gap between your head and your back, it can be beneficial if your helmet closes that gap with a tail.


That effect was also pretty cool with the P09 as well! I thought I was surely faster with it until I analyzed the data.

I’ll try it again for sure, perhaps in warmer weather at higher speed and reverse the testing order to block against any fatigue effect, but if I keep seeing the same less than 1W gain, I’ll have a very lightly used P09 for sale.

Haven’t the guys commented on this a couple of times on the AACCP? I recall that they did aero testing in a velodrome on one occasion and also that they had an extended discussion with specialized. Might be worth looking up these videos.

Youtube has a number of videos looking at aero setups and some cover helmets. GCN and GTN have some, Cycling week did a test or two. Bike radar did a vid. While I don’t think any of them looked at tri helmets, the vids do show that it is very hard to get good analysis of helmets. There are a lot of variables and controlling for all of them with precision is hard.

I had a POC Ventral (not air) and it was amazing how cool it was. You certainly could feel the air being ‘pulled’ over your head because it is a little more raised off of your head than my previous helmet. So as long as you we’re moving over maybe 12 mph it was great. Though if you do a lot of hot and slow climbing the air version may be better because of some passive cooling.

Unfortunately, that is a not a reliable indicator of aerodynamic efficiency.

This. I have read and researched a bunch and I came to the same conclusion. Aerohead is IMO the best for most people unless you can test in a wind tunnel, but at that point I am sure you have amassed a bunch of helmets or your sponsored. But yeah, aerohead is the best for most people. With that being said, the helmet is a tad heavy, so keep that in mind. It’s also worth noting that you might be better off with an aero road helmet rather than a full blown aero helmet, as cooling is impacted. I have an aerohead and love ti but riding anything over like 30C is an oven, so I picked up a Ballistia after a 40C IM when I legit cooked. IMO The LG is another solid choice if you don’t want to blow the money for an aerohead. You can find it for significantly less than an aerohead. Only downside is it looks slightly less pro. But most people say all aero helmets look pretty stupid. Personally I think the aerohead looks cool, but I am a triathlete so my style opinion is both skewed and also likely worthless :sweat_smile:

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@Power13 your point about being able to “turtle” was really helpful. I expect I am not very good at it. I think I will go long-tail, probably get an Aerohead MIPS b/c it is CPSC compliant (required at IM events, I think), and has the MIPS thing. Heat isn’t so bad in Colorado–relative to other places–so for races I’ll just keep my road helmet on-hand just in case it’s sweltering.

People talked about it peripherally, that “unless you have a wind tunnel” it is hard to know for sure what is fastest for you. I understand this, but it annoys me to no end (the lack of data). I have recently discovered the Chung Method and Golden Cheetah software, and have a couple good road loops nearby. So as soon as this effing snow melts I will be out there with my Garmin and power meter running tests. As a power engineer by training, I am lucky to be a big enough nerd that activities like this bring me great joy. So If I start to get a rhythm and consistency maybe I can share the results with you.


…And thanks for the discussion so far. This forum always brings my knowledge up faster than aimlessly grazing over Google search results.

I’ve got the Giro aerohead (with the short tail) - mainly because despite trying not to my head often drops in tt when the pressure is on (especially near the end of 25/50m events) and this seems fast in all conditions and with all head positions. Also as the running joke goes on the UK time trial scene - if I need to go to a fancy dress party I have a ready made Lord Vadar costume! :grinning:

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I would argue that the aerohead is basically a long tail (only comes in 1 type). Short tail would be like the Oakley AR07 or Kask Bambino. These typically test better if you ride head down. If you can keep the trailing edge down and in line with your back, you are typically better served with a long tail. Of course long tail used to be really long, but recent aero testing has proved you can get similar aero advantages with a shorter tail (similar to aero wheel shape developments)

This is why its always with respect to aero testing. If you know you ride head down most of the time and you bury your head into your aerobars, consider a short tail. Otherwise get a long tail.

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The data for helmets is notoriously personal.

If you can try to borrow a few helms mentioned above from friends or an online retailer (send them back after trying them on ;p) and take a picture of yourself while in the aero position.

I certainly seemed to go a bit quicker when I switched to the Giro - we have a ranking database in the UK called Spindata and my score improved once I switched to the Giro - or may I was just getting fitter at the end of the season…who knows!

My visual thought for turtling is to think about “collapsing” my shoulders blades towards each other. This will significantly lower you head relative your your shoulders.

A lot of people think about “shrugging” to get your head tighter with your shoulders, but IMO the benefit of turtling is to get your head lower, not necessarily tighter relative to your shoulders. Shrugging does this as a byproduct of the action and can be difficult to maintain. Just relaxing your shoulder blades is easier to hold, IME.

Someone also mentioned the weight of the Aerohead,it is definitely not a light lid. Another factor to consider is the large frontal area coming off the front of the helmet. If you have a high hand position, or can get your head very low, you can end up with your helmet hitting your hands. I run into this fairly regularly where I try and get my head lower (I have a very “head down” position) but can’t go any lower because of the helmet shape.

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Good tip. I’ll try that. I thought shrugging was more trying to reduce frontal area around the shoulders? If it helps lower the head then bonus.