Goood Helmet Design

Aug 27, 2012
581
234
73
London, UK
www.macrophotofly.com
#1
I posted a while back about Closed (and more aerodynamic) helmets ("Baaad Helmet Design") .Whilst flying over to Bangkok from Hong Kong this last weekend I found myself sitting next to an Aerodynamicist who has a plastics factory in China. After a brief sojourn into the latest aircraft designs, I mentioned my love of cycling and he explained he's just finished designing and testing a new closed cycling helmet.
As I long suspected the current open helmets are pretty inefficient and the design he has pulled together leverages the same basic principles as airflow through the interior sections of F1 cars. Essentially you need small turbulence-free openings with large exit holes and smooth channeled passages* over the head. The result will be a closed helmet with as much air flowing over the head as current open-styled helmets, but none of the drag. It will look odd to the eye with a larger rear section (think F1 blown diffuser) but actually the total length won't be any longer than current designs. He's even taken into account for people who want to wear cycling caps under it
The current working name for the helmet is "Free Speed" and should be launched from his factory within the year. He's already signed up a couple of smaller local teams to test it.
Frankly I'll be first in line for one to avoid slapping suntan lotion on my head (*and maybe my thinning hair will have one advantage after all)
 

FarEast

Maximum Pace
May 25, 2009
5,528
538
193
Yokohama
#2
Well the whole point of open helmet designs is to protect the head 1st while then offering some form of aerodynamis as a secondary feature to offset the the fact you have a block of foam on your head.

The closed design of helmets are again primarily to protect the riders head - Tim Johnson (CX rider) wears basically a skateboard/snowboard helmet and the new range of Giro helmets are a throw back to the BMX days and are designed for criterium and cx racing where a heavy crash is a high possibility. But also after testing in wind tunnels they found that they were more areodynamic and saved around 3w of power, however there is a drawback - they can be pretty hot in the summer and thus why you see them on shorter races. Some teams will actually switch helmets in the last 10-15km to benifit from the areodynamics.

Several companies started releasing helmets that although had the polymer outer they did not cut out the vent holes as it increased the aerodynamics of the helmet but to be honest I personally prefer a vented helmet that keeps the head cool and protected.
 
Aug 27, 2012
581
234
73
London, UK
www.macrophotofly.com
#3
the whole point of open helmet designs is to protect the head 1st
A good point and well made. I'd hope a closed helmet is slightly more safe than an open one

Several companies started releasing helmets that although had the polymer outer they did not cut out the vent holes as it increased the aerodynamics of the helmet but to be honest I personally prefer a vented helmet that keeps the head cool and protected.
As I understood it, this new helmet overcomes the need for large opennings by several techniques to increase the speed of the air entering the relatively smaller inlet points thereby matching the same volume of air over the head as an open design. There are still plenty of channels over the head (but under the closed outer rigid shell) to take the heat away and the aerodynamic gains are through the smoothed large rear diffusing vents. He also made the point that "most" current designs have a larger surface area to their opennings at the front, than vents at the rear (I checked mine yesterday and he was right on one of the two helmets I have) - a basic flaw.
I didn't actually ask him this point but my limited air and fluid dynamics knowledge would suggest that the new designs weak points compared to an open design are if (i) you tend to look around all the time rather than face forward (ii) ride very slowly so more heat moves upwards rather than blown off
 

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
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639
133
Kanazawa
#4
I have an LAS and thinning hair. It has enough of a liner/pad that I've never had to "shampoo" my balding head with sunblock.

Actually just replaced the liner, didn't get it in quite right and will try again sometime.

I'd certainly go LAS again. Besides the UV coverage, it's the most comfortable helmet I've had.
 

Yamabushi

Maximum Pace
Jun 1, 2010
2,335
188
1,083
Tokyo (Nezu)
fudoushin.com
#5
I actually like the look of the new "closed" Giro Air Attack helmet and the airflow benefits that macrophotofly referenced do indeed apply. The caveat is that that only holds true when you are traveling at pace and that the advantage in the real world probably isn't that major for most of us. Yes, the faster you are going the bigger the advantage in drag reduction and the better the "closed" style will ventilate, but in Japan most of us do an extensive amount of climbing. Climbing that is generally at a much slower pace than when we are traveling in the flats. This is were the "closed" design is going to be at its worst, IMHO. That being said, once the descent starts the "closed" helmet is back in it's element. All that being said, I'd like to have a Giro Air Attack as my winter helmet.