I have often wondered if there was any fact-based evidence that light colors and/or high visibility clothing on motorcyclists had any impact on safety. Well now I found some evidence. A 2004 study¹ (data collected between Feb 1993 and Feb 1996) conducted in Auckland New Zealand by researchers from the University of Auckland and funded by Health Research Council of New Zealand and the Accident Rehabilitation and Compensation Insurance Corporation produced some meaningful results.

Here are a few key findings:

1. ... drivers wearing any reflective or fluorescent clothing had a 37% lower risk than other drivers.
2. Compared with wearing a black helmet, use of a white helmet was associated with a 24% lower risk.
3. Self reported light coloured helmet versus dark coloured helmet was associated with a 19% lower risk.
4. Three quarters of motorcycle riders had their headlight turned on during the day, and this was associated with a 27% lower risk.
5. No association occurred between risk and the frontal colour of drivers’ clothing or motorcycle.

And, their primary conclusion:

Low conspicuity may increase the risk of motorcycle crash related injury. Increasing the use of reflective or fluorescent clothing, white or light coloured helmets, and daytime headlights are simple, cheap interventions that could considerably reduce motorcycle crash related injury and death.

Most of these findings are what you might expect, still it is nice to see the data support what is generally believed—that bright clothing makes you easier to see, leading to fewer accidents. However, you might find it surprising that the study did not find "frontal color" for clothing or the motorcycle made a significant difference. In the body of the study, the researchers suggested a possible explanation for the unexpected conclusion, "... 80% of the controls wore black, blue, or brown top clothing and black or blue clothing from the waist down. Owing to the small numbers wearing light coloured clothing, our study may not have had the power to detect an effect of brightly coloured clothing if it existed."

1 Motorcycle rider conspicuity and crash related injury: case-control study, Susan Wells, Bernadette Mullin, Robyn Norton, John Langley, Jennie Connor, Roy Lay-Yee, Rod Jackson, BMJ, doi:10.1136/bmj.37984.574757.EE (published 2 February 2004)↵