No impact. Styrofoam is a great insulator, and there is significant internal convective airflow.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Depends on how long your event is and how often it is in the sun and how extreme the sun is.

I have seen Black Glossy Coated Helmets( Vorttice black knight for instance) get damaged by the sun. I believe there is a sticker to remind you not to leave it exposed to the sun for prolonged periods.

Did a four hour ride in the hot sun with both my white and my black aero helmets. I seem to have sweated the same not sure if there is a heat impact.

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Rain*

My TT helmet is all black, I always clean it after using it to protect it. Good interior insulator with good airflow through the vent holes, compared to my red and black road helmet I'd have to say there equally the same.

I have used both light and dark colors and not noticed much difference in similar environmental conditions. As one sage guy at a bike shop put it: "You are sticking your head in a styrofoam cooler. I'm not sure the color is going to have that much of an impact."

I think he has a point. :-)

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Jeffrey Sankoff, MD
TriDoc Coaching/TriDoc Podcast
Train hard, train healthy
http://www.tridocpodcast.com
http://www.tridoccoaching.com

As others have said the helmet's foam is an excellent insulator. Color will have almost zero impact on temperature inside the helmet.

I know in theory it should not matter. However I have both a black and a white Giro selector (not much ventilation) and the black one definitely feels hotter. On the other hand, I notice no difference between white and black Evade (which is well vented to begin with)

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Are you ready to do an Ultraman? | How I calculate Ironman race fueling | Strength Training for Athletes |

Performance in 12km time trial 100 deg F

Regular helmet:
AP: 255 watts
HR: 175bpm
sweat rate (l/hr) 2

Aero Helmet:
AP 260 watts
HR: 175bpm
Sweat rate (l/hr) 2


that is one subject from this study:
http://www.ncbi.nlm.nih.gov/pubmed/23539083

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

The polystyrene shell on most helmets will soften at 177^F. A dark helmet left in a car dashboard could easily get this hot. It's possible (Quatar) for this to happen with the helmet sitting in transition on a very hot, sunny day (though very unlikely). While riding, the convective cooling will be more than enough to keep the shell from reaching this temp.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)