Aero Helmet

Discuss light weight issues concerning road bikes & parts.

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topt
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by topt

FlatlandClimber wrote:
Fri Oct 30, 2020 4:31 pm
Image

There you go.
Specialized is evade 2, Kask is Utopia, Lazer is Bullet 2.0
thank you very much

by Weenie


topt
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by topt

robeambro wrote:
Fri Oct 30, 2020 6:09 pm
Can't quite figure out how the Lazer Bullet can manage to be 2w slower than a Prevail. Is the honeycomb pattern making it slow? Is the Prevail maybe benftiting from a smaller form factor? Can't imagine how slow the Genesis must be. Primoz Roglic doesn't like this study :lol:

A pity there's no Giro helmets, would be curious to see how an Aether tests against the Evade.
if I had to guess not very good.
I would like to see how the Rudy Project boost pro does against evade; it looks very aero

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JayDee81
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by JayDee81

Does Tour mag test helmets for aero?

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BikeEatSleepRepeat
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by BikeEatSleepRepeat

icantaffordcycling wrote:
Tue Nov 03, 2020 8:39 am
Any update on smuggling HJC helmets into the US?
I got one in from a distributor in Japan last spring.

Nice and very light, but I ultimately went with Kask as for me and my position it was clear the Utopia was more aero in real life on the road and also better ventilated. Noise level noticeably less on the Utopia, too.

AJS914
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by AJS914

I wonder if there is directionality with aero helmets that cannot be tested. It's kind of hard to describe but I got a Ballista last year and you can definitely feel it catching the wind. You turn your head towards the wind and feel the airflow smooth out. I wonder if just turning your head a few degrees in one direction is saving measurable watts.

I was watching Roglic yesterday in the ITT and he was constantly moving his head up and down - up to look and then back down looking at the ground. One would think that keeping his head in one place would be the fastest. If you watch Ganna or Dennis ride a TT, they hardly move their heads at all.

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JayDee81
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by JayDee81

AJS914 wrote:
Wed Nov 04, 2020 5:07 pm
I wonder if there is directionality with aero helmets that cannot be tested. It's kind of hard to describe but I got a Ballista last year and you can definitely feel it catching the wind. You turn your head towards the wind and feel the airflow smooth out. I wonder if just turning your head a few degrees in one direction is saving measurable watts.

I was watching Roglic yesterday in the ITT and he was constantly moving his head up and down - up to look and then back down looking at the ground. One would think that keeping his head in one place would be the fastest. If you watch Ganna or Dennis ride a TT, they hardly move their heads at all.
Most TT helmets have this vent in the back that sends the airflow onto your back and actually speeds you up, so if you have a helmet like that it is definitely faster to keep your head level. Hambini talked about it in some video of his and you would surely find other sources too.

Nickldn
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by Nickldn

JayDee81 wrote:
Wed Nov 04, 2020 9:07 pm
AJS914 wrote:
Wed Nov 04, 2020 5:07 pm
I wonder if there is directionality with aero helmets that cannot be tested. It's kind of hard to describe but I got a Ballista last year and you can definitely feel it catching the wind. You turn your head towards the wind and feel the airflow smooth out. I wonder if just turning your head a few degrees in one direction is saving measurable watts.

I was watching Roglic yesterday in the ITT and he was constantly moving his head up and down - up to look and then back down looking at the ground. One would think that keeping his head in one place would be the fastest. If you watch Ganna or Dennis ride a TT, they hardly move their heads at all.
Most TT helmets have this vent in the back that sends the airflow onto your back and actually speeds you up, so if you have a helmet like that it is definitely faster to keep your head level. Hambini talked about it in some video of his and you would surely find other sources too.
My Oakley AR07 arrived today. Certainly has a few vents at the back, I too have read these vents are a substitute for the pointy back on some aero helmets. The vents work by letting out air, which helps to re-attach airflow going around the helmet and hence decrease air resistance. The advantage is that it works in more head positions, so it's more effective for non extreme TT straight back/head up type riding positions.
Giant Propel Advanced SL Red Etap 11s Easton EC90 wheels 6.5kg

maxim809
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by maxim809

AJS914 wrote:
Wed Nov 04, 2020 5:07 pm
I wonder if there is directionality with aero helmets that cannot be tested. It's kind of hard to describe but I got a Ballista last year and you can definitely feel it catching the wind. You turn your head towards the wind and feel the airflow smooth out. I wonder if just turning your head a few degrees in one direction is saving measurable watts.

I was watching Roglic yesterday in the ITT and he was constantly moving his head up and down - up to look and then back down looking at the ground. One would think that keeping his head in one place would be the fastest. If you watch Ganna or Dennis ride a TT, they hardly move their heads at all.
I think you're bringing up a great nuance with aero helmets, which is building on the earlier points that we can't just look at a simple 1D bar graph when comparing aero helmets.

By directionality, you're talking about [yaw, roll, pitch] of the helmet, with respect to the ground. It's definitely quantifiable, but the cost to collect all 3 dimensions is what makes it impractical. We could reduce the test points by first identifying the individual rider's optimal riding position(s), and sweep across a range of "realistic" yaw/roll/pitch for those said positions. Then repeat these measurements for each aero helmet the rider wants to test against.

After conducting this massive sweep, we'd find that some aero helmets will test faster at certain yaw/roll/pitch than others. The rider could use this data to make a decision on what's optimal for their goals: whether that's the fastest helmet in a rigidly uncomfortable but sustainable position for a 1hr TT or crit/RR breakaway, or a helmet that is fastest in a "comfortable" sitting-up riding position, but may not be the fastest in the most aggressive arms 90° bent riding position.

And these results would be highly individual per rider. If we each had unlimited time in a wind tunnel, we could quantify all this to save around 1~7 watts from whatever helmet we are each using now.

Of course, since this is all an impractical pipe dream for the majority of us... we each have to base our decisions on price, looks, fit, ventilation, safety -- combined with our own "best guess" on what might be fastest aero helmet for us. I think that's the best we really got.

I guess some pro tips are... the reason why we should put sunglasses over the helmet straps is not to please traditionalists, but because it is more aero to not have the gap from the strap flapping around.
Currently building a: Basso Diamante

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wheelsONfire
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by wheelsONfire

^
Wors with glasses over stap is when you just undo lock and rip off helmet.
Glasses will be ripped off to :-(
Done that, uh hu hu no funny!
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
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Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

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micky
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by micky

BikeEatSleepRepeat wrote:
Wed Nov 04, 2020 3:55 pm

I got one in from a distributor in Japan last spring.

Nice and very light, but I ultimately went with Kask as for me and my position it was clear the Utopia was more aero in real life on the road and also better ventilated. Noise level noticeably less on the Utopia, too.
What was the weight difference in them? What sizes?

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BikeEatSleepRepeat
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by BikeEatSleepRepeat

micky wrote:
Thu Nov 05, 2020 8:57 am
BikeEatSleepRepeat wrote:
Wed Nov 04, 2020 3:55 pm

I got one in from a distributor in Japan last spring.

Nice and very light, but I ultimately went with Kask as for me and my position it was clear the Utopia was more aero in real life on the road and also better ventilated. Noise level noticeably less on the Utopia, too.
What was the weight difference in them? What sizes?
The Utopia I have is 258g in size Medium (CE cert), and if memory serves the Furion was 219g.

Nickldn
Posts: 502
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by Nickldn

Oakley AR07 first impressions:

* Feels more like a motorbike helmet, much thicker and bigger, but also a lot more secure. Protects the ears, which is good in the winter. Visibility is fine too.

* Airflow is surprisingly good, but not quite as good as a 'normal' helmet. Would use this helmet in the summer up to about 30 degrees C.

* Brow pad with rubber gripper is very effective at preventing sweat dripping onto the visor.

* Magnetic buckle is great. So easy to use.

Too soon to know if it's faster.

You might get the impression I'm liking the helmet, but unfortunately it has a fitting issue. The helmet slides forward on my head when I'm in the drops and obscures my vision. Really annoying and no way to prevent it. :cry:
Giant Propel Advanced SL Red Etap 11s Easton EC90 wheels 6.5kg

topt
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by topt

AJS914 wrote:
Wed Nov 04, 2020 5:07 pm
I wonder if there is directionality with aero helmets that cannot be tested. It's kind of hard to describe but I got a Ballista last year and you can definitely feel it catching the wind. You turn your head towards the wind and feel the airflow smooth out. I wonder if just turning your head a few degrees in one direction is saving measurable watts.

I was watching Roglic yesterday in the ITT and he was constantly moving his head up and down - up to look and then back down looking at the ground. One would think that keeping his head in one place would be the fastest. If you watch Ganna or Dennis ride a TT, they hardly move their heads at all.
Definetely but its just really hard to keep the head in the same position; thats the reason they got rid of long tails, they are faster if you keep your head straight but as soon as you look down it slowes you. I saw the same problem with Jay Hindley on Giro TT, he had quite a long tail and kept looking down.

pmdd72
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Joined: Sun Apr 11, 2010 8:47 pm

by pmdd72

One thing I'm curious about is the difference in aero performance when you go up/down sizes with the same helmet. For example, I'm on the border size wise between a medium and small ballista, according to Trek's sizing guide. The medium certainly feels better but no doubt the greater frontal area would reduce aero gains. The question is by how much? Is it a big enough difference to give up some comfort?

Hexsense
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by Hexsense

^ size matter far less than shape.
round tube creates same drag as aerofoil shape 20 times larger than it.

Get something you fit properly so that you can comfortably wear it in optimal angle against the wind.
Maybe, medium can be even faster because the air go through space in the helmet instead of over and around it.

by Weenie


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