Doubt it matters much. My team kit is bright yellow, black and orange spots (seriously) and I ride over 11K miles/year and idiot motorists still don’t “see” me at times. Just learn to anticipate, ride the road bike only in traffic situations instead of in the dork bars, etc. I have 4 or 5 helmets I rotate through of various colors and see no difference 
Doubt it matters much. My team kit is bright yellow, black and orange spots (seriously) and I ride over 11K miles/year and idiot motorists still don’t “see” me at times. Just learn to anticipate, ride the road bike only in traffic situations instead of in the dork bars, etc. I have 4 or 5 helmets I rotate through of various colors and see no difference
dork bars 
LOL
I wear a white helmet and have recently started riding with a flashing light on the bars. Someone still pulled out right in front of me last weekend.
For every situation a white helmet might stick out, there is probably another situation where dark helmet on a light background might make a difference. Its really a crap shoot so just get what you like.
My $.02: go with the white helmet, sometimes that bit of conspicuity is the difference maker, I say give yourself every little advantage
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I’d go for neon yellow-green, because our eyes are most sensitive to that wavelength, and the sun puts off the most of it.
Then add good reflective tape all around.
Add some small lights to your helmet, and you are ready to ride.
That’s what I do, and I haven’t been hit yet.
A friend of mine picked up one of the ‘Fluo’ colored helmets from Rudy. http://www.rudyprojectusa.com/index_inner.php?group_id=3&cat_id=112
It sticks out like nothing else I’ve ever seen.
Studies have shown that black is the hardest to see but white is most quickly ignored by the brain. Go bright–red or yellow
I have thought about this to. But if you look at the design of many helmets, what you see from the back is the black foam. Picture below is me climbing Mt Lemmon wearing a white Rudy Project helmet. But from the back, it’s mostly black. What you see is the jersey!
Position is also a factor - particularly with TT and triathlon positioning - from ground level and from the rear, the helmet may be obscured by the persons back!
I agree that a more visible colour may be “better”, but in the real world, it’s not that great a contributor to visibility.
Now from the front, that’s different story, but things coming at me from the front are more my responsibility to see and look out for.
FYI - I just bought a new helmet. A black Giro Atmos!!
Motorcycling generally advocates a white helmet as the safest. I did a quick search online and couldn’t find any research to support it, but did see that reiterated in a number of motorcycle training handbooks.
Personally, I believe that Fleck is right, on a bike, people don’t really see the shell of the helmet (at least from the back)…my suggestion would be to focus on the colour of your jersey.
Hello pi and All,
X2
Good call.
Modern fire engines are not red anymore.
From: Human Factors and Ergonomics Society
Fire Truck Color Is A Life-or-Death Issue
The wail of sirens, flashing of lights, and appearance of a red fire truck provoke interest, excitement, and a sense of danger. There is danger not only in fire fighting but also in responding to the fire scene. The National Fire Protection Association reports that fire apparatus accidents are the second-largest cause of firefighter deaths (Washburn, LeBlanc, & Fahy, 1995).
Driver safety training is a common component of fire department injury reduction programs and has been for several decades. Yet fire apparatus accidents continue to occur. In this article we will explore the possible contribution of fire truck color to these accidents and make recommendations for improved visibility.
Color and Safety
A review of human visual color functions sets the stage for questioning the fire vehicles. In the mid- 1800s, Helmholtz wrote about the human eye as red-weak. When human eyes are adapted to daylight (photopia), the color red is seen with much greater difficulty that are most other colors. At night, when eyes are dark adapted (scotopia), they are practically red-blind (Hart, 1992; Southhall, 1961). Traquair (1949) found that certain colors can be seen farther into the visual periphery than others, thus offering earlier detection. Red has a narrow lateral range, whereas yellow’s range is much wider (Traquair, 1949). Allen (1970) stated that color-defective individuals struggle with the color red but can see yellow much more readily. In fact, 8% of the male population is red/green defective; of this group, 25% are red-blind (Allen, 1970).
In an attempt to make fire apparatus more visible, fire officials often paint the vehicles in two tones. The most popular combination is red and white - the logic being that red is used for tradition and white for visibility. Unfortunately, red/white two-tone lists tenth (near the bottom) on the visibility list for paired colors (Nathan, 1969). Sleight, in his research for the Highway Research Board, pointed out that two-tone colors may actually camouflage vehicles against the background (Leonard & Sleight, 1967). These findings lead us to ask, Does the choice of fire vehicle affect accident probability? What color is the safest?
We recently demonstrated that the probability that red and red/white fire apparatus will be involved in an accident is greater than that of lime-yellow/white fire apparatus. We focused our analysis on a single city - Dallas, Texas - to reduce the effect of variables such as training, law enforcement, traffic densities, weather conditions, apparatus operation, vehicle inspection and maintenance, and length of runs. We chose Dallas because both lime-yellow/white and red and red/white fire apparatus were simultaneously in service and geographically uniformly distributed during the period 1984 through 1988.
Which Color Is Safest?
Recently, DuPont researcher Dr. David H. Alman measured chroma and reflectance of DuPont paints typically used in the transportation industry; his studies were conducted under controlled lighting representing daytime and nighttime illumination. Lime-yellow (reflectance peaking near 550 nm wavelength) was shown to have the “best fit” for the sensitivity curve of human photopic (daylight) vision. Thus, the daytime and nighttime eye response to lime-yellow is strong, enabling more rapid reaction. Because lime-yellow is also an intense color, it is easily distinguished from rural and urban backgrounds (Allen, 1970). These factors, combined with reflectance approaching white, make lime-yellow a prime candidate for the safest color for fire apparatus.
Where Do We Go?
Color choice within a given finish type is not cost driven, so vehicle safety can be enhanced without added cost. From a human factors perspective, there are two broad areas of professional application: First, the fire service must be convinced to move from the traditional but unsafe paradigm of red apparatus to safer lime-yellow colored vehicles. Second, the manufacturers and purchasers of motor vehicles must be educated as to the potential of color to reduce accident rates and accident severity.
Excerpts from “Fire Truck Visibility” by Stephen S. Solomon & James G. King, in ERGONOMICS IN DESIGN, Volume 5, Number 2, April 1997. Copyright 1997 by Human Factors and Ergonomics Society, P.O. Box 1369, Santa Monica, CA 90406-1369 USA; 310/394-1811, fax 310/394-2410, hfes@compuserve.com. To obtain a copy of the entire article, which includes full references, contact Lois Smith at the address given above.
And you can up the ante and go DayGlo (color - only better) lime green.
That said … a flashing strobe light is hard to beat.
http://www.dayglo.com/...rescent_color_theory
How do fluorescent colors behave differently?
Fluorescent colors use a larger amount of both the visible spectrum and the lower wavelengths compared to conventional colors. They not only absorb and convert light energy of the dominant wavelength, but also the wavelengths of ultraviolet rays and other colors lower in the visible spectrum. As a result, your eye perceives a far more intense color.
Where a clean, bright conventional color is able to reflect a maximum of 90% of a color present in the spectrum; a fluorescent color can reflect as much as 200% to 300%.
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Cheers,
Neal
this little guy paired with a stinger or better yet a cherry bomb are on all my bikes and the back is always on and the front is only off in group rides.
Motorcycling generally advocates a white helmet as the safest. I did a quick search online and couldn’t find any research to support it, but did see that reiterated in a number of motorcycle training handbooks.
because motorcycle police wear white helmets. people see a white helmet and automatically assume it’s a motor officer, thus they mind their p’s and q’s. a bicycle helmet won’t have the same effect.
cheers!
-mistress k
a few years back in the Fall, I was riding my mtb on some cattle/game trails near Slide Lake in the Teton Natl Forest (before there were more legitimate trails/options). Towards the end of my ride I came across a hunter who advised me that when viewed through the brush, my white helmet could be easily mistaken for the rear end of a deer/elk.
I’ve since chosen brightly colored (non-white) helmets for off-road use.