Old 06-24-10, 09:37 PM
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Definitely a personal thing.

From my tunnel session - I was restricted to a smaller number of helmets due to only a few having Australian compliance (we have a separate standard down under) and tested the Limar Speed Demon vs the Limar Crono 5 and the CE approved Bell Meteor II.

I initially bought the Limar Speed Demon as it 'looks' faster with the longer tail. I also have an 07 Bell Meteor which I had used in Triathlons (rules allow non AS tested helmets) and initially tested both in the tunnel to see if there were any differences in the two helmets (The CE certified helmet can still be used on the track too) and then it was suggested I try the Limar Crono 5.

Although shorter, the Chrono 5 with minimal venting (none on the front section) offered me a noticeable wattage saving of 10 watts over the longer tailed, vented and sculptured Speed Demon. The Chrono 5 also compared favourably even against the Bell which with it's long tail that sits nicely against my back. As you can guess, I immediately sold the Speed Demon and bought the Chrono 5!

As for the Giro Advantage II. Another rider in the tunnel that day had previously field tested this helmet against the Limar Crono 5 and also found a similar discrepancy between the two which was confirmed in the tunnel.

If you have a PM, a quiet loop or velodrome in calm conditions plus a friend you can borrow these helmets from I'd suggest some field tests to see what works best for you if you can't get to a tunnel.

In the mean time - One study - details posted previously on BTR...

There is a WT test concerning several aero helmet versus a regular helmet Crazy Creek. From Triathlon Mag's Triathlon Training Issue # 10 Aug / Sept 2008.

The procedure: A dummy as in the earlier test.

Cat Cheetah bike (monocoque), tri-bar riding position, just helmets changed. Wheels not turning (supposed minimal influence on head level turbulence?). Wind speed 40 kmh.

Tested in 3 positions: 1. Helmet flush to back 2. Tip pointing up 3. Helmet sideways.

The Helmets
Alpina Venga
Bell Meteor II
Giro Advantage
Ironman Helmets Stealth
LAS Cronometro
Lazer Bullet
Louis Garneau Rocket Air
Spiuk Kronos
Uvex FP-2

Helmet flush to back:
Uvex 173.14
Alpina 173.47
Bell 174.11
Giro 174.68
Spiuk 176.17
LG 176.89
Lazer 177.82
Stealth 178.14
LAS 178.83

Tip pointing up:
LG 187.41
LAS 188.09
Giro 188.78
Stealth 188.95
Lazer 188.98
Uvex 189.54
Bell 189.79
Alpina 190.31
Spiuk 191.40

Giro 189.99
Lazer 190.27
Alpina 190.59
Uvex 190.75
Spiuk 191.26
Bell 191.44
LG 191.60
Stealth 191.80
LAS 193.26

So, LG would be the best helmet for a "tip constantly up" rider, and LAS the worst for a "paranoid where's my minute man" type of TTer

They also tested ventilation: First heating the dummy's head to 60 centigrade, then after 3 minutes in the 40 kmh wind measured the temp again.

Results (temp after 3 mins)
Stealth 36.4
Spiuk 36.6
Lazer 37.3
LG 39.1
Giro 40.8
Bell 41.2
Alpina 42.4
Uvex 42.6
LAS 43.2
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