Time Trialing - The Helmet Conundrum

Hey Time Trial and Triathlon Fans,
I am right now in the process of improving upon every little aspect of my time trialing, in order to challenge for state championships (Northern Germany region, not super competitive) next season. I‘ll make a bigger post about that, once a few things have happened and I have results to report. I have calculated, that I‘ll have to be „50 Watts faster“ to have a shot at it. I will expand upon this in another post.

Regarding this post:
One of the biggest savings is of course the position, and the helmet, which hits the air first, and also manipulates the airflow over your back.
I have good connections to LBS and therefore have access to several of the state of the art TT helmets, and currently try to find helmet and position, that looks/feels fast.
I will of course do real world testing, but not before I found a good basis.

The biggest conundrum I am facing here is, that the helmets either fit the shape of my shoulders very well (which is supposed to shelter the shoulders and reduce drag), OR touch to my back (potentially helping with keeping air attached and reducing Cd). I have yet to find a helmet that does both. I have looked into pro cyclists, and many seem to have a similar issue, which leaves me puzzled as to what position really is desirable. I know I could take it to a wind tunnel, but those results are often not comparable to real world results and also, most of them are closed due to COVID. Additionally, I still need to be able to hold and produce power in that position, so the analysis of the rider while producing power on the turbo, is probably as good as it gets for now.
Here are some findings with popular helmets in pro tour cycling:
Exhibit A is the world champ himself, who has the helmet touch to his back when looking forward. When he looks down, the helmet doesn’t touch anywhere, but mimics the shape of his shoulders a lot better.

Comparing that with Egan Bernal using the same helmet, albeit being the much worse time trialist than Ganna, his position actually looks faster in terms of frontal area and keeping air attached.

Rohan Dennis uses the very similar Kask Mistral, and his position looks more upright, with a bigger gap between helmet and shoulders.

Another helmet that has been used in the pro tour is the S-Works TT. The helmet looked great to me on paper, because the more voluminous tail, looked like it could be snug to the neck…

For Remco, it actually looks pretty good, while it doesn’t look good at all for Ala.
However, when they start tucking their heads in, the tail sticks up in the air and looks like creating a lot of drag:

Either way, I have now tried both, the Mistral and the S-Works, and I can‘t manage to get anywhere comfortable with the S-Works.

After testing out the two over a 90 minute session, the clear winner here looks to be the Kask (for me that is). I was pedaling for several minutes at threshold, to make it somewhat realistic being able to hold the position.
Next, I will test the Met Drone, Giro Aerohead and Kask Bambino Pro EVO.
I will post the pictures to this thread.

The best position (!) to my eye (!) I have found, with a helmet matching a great TT position is actually Justin Rossi, who I guess we all know from „The Chase“.
His position with the Giro Selector (now discontinued) is awesome. It keeps the line with his back very straight to keep air attached, yet shelters his shoulders almost perfectly.

Why am I making a posting this and not keep it private?
I guess, I am not the only one who is faced with this situation and hope to have others give their input, give my advice on what to tweak and of course, post images and questions of their own. Very interested in what you guys have to say on this topic.


As with everything aerodynamic, this is going to be individual and what works for one, or many people, may not work for you… this is from experience and proved expensive :slight_smile:

I spent a lot of time testing various helmets on a velodrome (11 in total including all you have listed) and landed with the Giro Aerohead, this is how it looks when in position:


Do you have a power meter on your TT bike and access to a decent quiet piece of road?

If so, you can run this data through AeroLab within Golden Cheetah to establish your CdA with different helmets.

Also, be careful when comparing with pros when they are racing for their teams as the helmet worn is generally decided by sponsorship.


Hey there,
Thanks for your contribution. Your position with the aero head looks really good.
I know how individual position and helmet choice is, but there are definitely things to derive from a „working aero position“ of someone else.

Yes, both. I will definitely do testing this way a bit later.
I have all winter and most of spring before the State Championships so I am in no rush. Therefore I wanted to first see what might work and then work on being able to hold that position. If I just go out, do test runs and pick a winner, I might have a self-fulfilling prophecy. I have raced the mistral all year now and will get a long with it much better, than with any (or at least most) other helmets, that I have no experience with. That doesn’t mean the Mistral is the fastest helmet for me period, just that I have done the most to make it work for me.
Any of the other might be as good or better, but to give them a fair chance, I first need to find the right tuck with them.

What you say about sponsored equipment is absolutely right. During the nationals and euros, Remco used a different helmet that looked better on him, while Ala mostly races the S-Works,
With that said, I think all of these helmets have their place and probably each one of them will be the fastest for someone. It is very interesting that you have gone though such extensive testing already and chosen the aero head (which tests fast for many). The Aerohead and Mistral are actually my own helmets, and I got the mistral because I felt the Aerohead wasn’t working for me, no more scientific basis to that. I’ll work on making it work and see how it looks.

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The UK time trialing scene is massive at the moment and there has just a series of high profile races… national champs at various distances as well as closed circuit races. There are hundreds of photos of all the riders at different points in the race and from different angles… can easily be found on facebook or on www.timetriallingforum.co.uk Take a look what equipment the fast guys are using.

It took me months of testing to pin down equipment and a position that worked for me but I then had it validated, and tweaked further, at a velodrome but I am now pretty happy.

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@Aeroiseverything earlier this year I did a ton of aero testing & the helmet results were the most surprising of all. My advice is don’t spend too much time looking at pictures! In my case intuition was a poor guide! You have to do the testing.

Position seemed to be a little more intuitive but when you get down to the nitty gritty details of your front end (or ‘the nose cone’ as my mentor called it) you really do have to test it. How close should your elbows be? What angle should your forearms be at? What angle should your upper arms be at? How high should your elbow cups be? Those are all things you just gotta get out and test.

We spent hours & hours…literally hundreds of miles…riding around in circles just before sunrise figuring those things out. Beforehand, for sure, I would have picked my Kask Bambino as my fastest helmet. No matter how I tested it, it was always my slowest. I still can’t believe it…but it’s just about the same as my Kali Tava. Your noggin may vary (and in fact almost certainly does)


Very interesting input, thanks for sharing.

Out of interest, how much difference was there between the best and worst helmets from your testing?

My fitter’s advice on this was that if you’re not going to spend a load of time testing (whether in the tunnel or on a velodrome) then going with a relatively short-tailed helmet was probably the safest option since they tend to be more forgiving across a range of positions, and that you likely weren’t giving up many watts compared to your theoretical optimal helmet. I’ve heard from him and others that some of the more extreme helmet designs (e.g. the POC Tempor) can test very fast if they work well for you but can also cost you a lot of watts if your position is a little off. I’m using a POC Cerebel on the not particularly scientific basis that I got a good discount on it, the colour matches my club skin suit, it’s comfortable, and it apparently tends to test reasonably well across a range of positions, while rarely ever being the outright fastest. I know head position is something I need to improve, particularly through technical sections, so figured I’d sort that out first before maybe doing some more scientific helmet testing.

I’ll echo the sentiments above to test as many helmets as you can. I had a Poc Cerebel that I swore looked perfect in my position but after testing the aerhoead came out better. Comparing pictures can be pretty deceiving, as even in these your shoulders are quite different, which changes how the helmet fits. You could probably get the S Works to touch your back if you turtled like the Kask. Also be very conscientious of comfort when selecting position/ equipment changes. It can be really tempting to convince yourself you’ll be able to tolerate it, especially when you see those few watts you’ve been chasing, but when you’re 45 minutes into a 40k you want to be putting your energy into holding your power, not holding your position.

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Another option:

Head position is critical… during testing I saw up to a 10w difference between head in a neutral position to a lower position with shrugged shoulders. If you are going to TT this is something that needs training as well.

In terms of helmets alone, the range was 17w… the worst was 10w slower than my baseline test and the best was 7w faster.

I think to a certain extent, your fitter is right… if you are not TTing regularly then you will probably move around on the bike and not hold a consistent position and in general, short tail helmets are more forgiving in these circumstances… I did test the POC Cerebel and was 5w slower than my baseline test.


Just a suggestion: Could you be over thinking this? Some thoughts

  1. There are simple tests using the Chung approach you can do yourself in the real world. For me, in none ideal circumstances I was able to pick up the difference between a shrugged and non-shrgged head position (and different front wheels). (Look up Chung, then use Golden Cheetah.). In other words, stop over-thinking it and go and do some real world experiments would be my suggestion.
  2. There are a whole host of assumptions in your long introduction (Shoulder positions and helmets, smoothness, , gaps etc.). Are they actually true? How do you know?
  3. On the minor issue of the Specialized, I though the “gap at the back” was to let air out and smooth the flow, so it is more aerodynamic.
  4. I do TTs from 10m to 12hrs. I am a very average TTer, though had a few good results for my age and ability and am still learning. I demand comfort and aerodynamics from my helmet. I am very happy with a Giro Aerohead. Teammates have the Kask Mistral and I could have had one at a great price, but choose not to. The reason.: The giro was probably fine and ther was much much more I could do with my body and power and fitness and nutrition during races, that would give me more bang per buck.
  5. Sometimes helmets come down to comfort and fit. My aerohead often gives a high pitched whistle/reverberation on dual carriageways with concrete surfaces and tyre noise. So I simply wear ear plugs to mitigate it and can still hear the traffic around me. I like that the visor parks easily. In a long race I could park it, then refit it if it rains. The point I am making is we are not pros and sometimes a simple compromise solves a problem.
  6. Can you hold your head in a position that still looks up the road, is fine for your shoudlers and arms and is still areo. its a personal thing. My neck has some age related stiffness. Yours might be a different shape. If you are constantly looking down, that is as much a physical issue as a helment issue. (The helmet tail pointing skywards just makes it worse).

There is a bigger piece here. These pros are all on different bikes with different arm positions. Each one works for them. Frankly, I doubt there is a big real difference amongst bikes. Can you get in the position on them, counts for much more. And they are far far more flexible than most of us. I think personal felxibility (esp, around glutes and hamstrings and neck) can make a massive difference.

Almost finally - I had a TT bike fit recently. Looking at my positions before and after, they look very similar. Actually they feel dramatically different and afterwards is much faster. Flexibility played a big part. Also there is a whole thread on Facebook of people criticing other people’s positions from a picture. Frankly, I really do not think you can tell as much, as people make out, and they assume so much.

Finally, I am facsinated that your LBS allows you to sweat in a helmet to try it out… and then return it… (Remind me not to use them… :))

Good luck with this. (A practical TT cynic :slight_smile: )


… or 60 miles into a 100m, or 10 hours into a 12… :slight_smile:

Unfortunately, not really…aerodynamics are a tricky thing. What “looks” good can often not be IRL.

As everyone else has noted, helmets are VERY individual and the only way you can determine which one is “best” is through testing.

That said, there are some options that generally test well for the majority of riders, and lacking any individual testing, you can probably choose one of those as a “safe” or “fast” option, but maybe not the “fastest”.

In no particular order, some of those helmets are:

  • Giro Aerohead
  • Giro Advantage2
  • Louis Garneau P-09

IIRC, Jim at ERO Sports has said helmets like the Kask Bambino tend not to test well unless you can consistently keep your head below your shoulders. But again, this is very individual.

It is hard to compare the two pics you posted because your head is not in the same position. Your head is much better “turtled” with the Kask (compare the gap between your chin and upper arm to see what I am referring to).

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I did an hour long session with the s-works and I couldn’t get it to work. I have put a „focus point“ that is about where I „have to look at“ to see the road outdoors. The picture I uploaded is the best when still being able to see. This picture is when not being able to look above the handle bar:

Just by the looks, I get into better positions with longer tails.

I had real visibility problems with S-Works helmet and was one of the reasons that I couldn’t get it to “work” for me. The head position required to see was not aero… head position to be aero, I could not see and was not safe.

“best” based on what, though? Again, how a helmet “looks” against your back is not necessarily a reliable indicator of aero.

One additional thought on the Aerohead…the front of the helmet comes a fair bit forward. It is not relatively flush against your forehead…there is a definite point to the front of it. I keep a very low head position (often looking down…don’t @ me :stuck_out_tongue_winking_eye:) and the forward point of the helmet can occasionally stop me form getting as low as I want / could.

You definitely have a low head position, so a shorter tail helmet like the original Bambino or the POC Cerebellum could be worth checking out.

That is correct. However, I do have quite some experience on what has worked for me in the past, and also have an aerodynamics engineer overseeing my testing every now and then. That still doesn’t mean it will be fast in the real world, but you can still get to point of „fast for most people“, and then test out what really works for you individually.
I have also had professional analysis of my position, focused on reducing frontal area, and my current position (arms, back, head) is pretty good at that.

Regarding your comment on the short tail helmets. As far as I understood, they are made to „work for everyone“ and also in a variety of head positions. I know, that this has been disproven to be the Case. Like any other helmet, the do not work for everyone and not in every position. However, I don’t need a helmet to allow me that, because I have been pretty solid at keeping my head in place and also, I have rather short races scheduled.

Met Drone rounded back/ head tucked position:

Met Drone with flat back:

That last one looks lightning fast, but the hip angle is super tight…


Yes, the helmet seems to fit the profile of your back but you have had move you shoulder, elbow and hand position to achieve this… from this angle, your shoulders seem to be much wider thus increasing your frontal area and this can easily offset any benefit you have gained by moving the tail of the helmet into a better position.

You need to be thinking more holistically and the reason that you need to test, test, test and then test some more to get a real answer to this question.

You said that you have a power meter… all you need is a selection of helmets (you seem to have access), a quiet piece of road (an outdoor track is ideal) and bang your data into Golden Cheetah or manually run through the Chung method to get your results… no self fulfilling prophecy, the numbers do not lie :+1:

You are absolutely correct, that the position has greater effects than helmet position. I have done frontal area analysis, and we found, that my flat back, straight neck, „wide“ shoulders is almost identical with the rounded back, tucked in neck, narrower shoulders. That is A, Cd is another thing. My frontal area is pretty small already for me being a tall guy. That is why I Analyse the looks from the Side.

I have done on road analysis and found the Kask mistral being quite a bit faster for me than the Aerohead. However, I have never given thought to me using the helmet „incorrectly“, or not getting into the position, that fits a certain helmet design best.

Regarding moving forward with a flatter back. I have to move forward for that, to not get my hip angle too narrow. I tried moving my saddle back, and it lead to production of power dropping by 10%.