On 4/5/2018 2:46 PM, jbeattie wrote:
On Wednesday, April 4, 2018 at 9:52:40 AM UTC-7, sms wrote:
On 4/3/2018 8:16 PM, jbeattie wrote:
On Saturday, March 31, 2018 at 10:53:35 AM UTC-7, Frank Krygowski wrote:
On 3/31/2018 12:00 PM, Jeff Liebermann wrote:

The fallacy also works for the absence of evidence. (Absence of
evidence is not evidence of absence). An unchanged accident rate
after the introduction of mandatory reflective clothing does not mean
that reflective clothing does NOT have an effect on accident rate.
There could easily be a counter balancing effect. For example, it
might be that riders tend to ride more aggressively when wearing a
reflective vest on the assumption that the vest would protect them
from harm. At the same time, vehicle drivers would more easily notice
bicyclists. The two effects cancel each other resulting in an
unchanged accident rate.

In the cycling community, there are many who believe absence of evidence
is trumped by an anecdote or two - as in "I _know_ that people no longer
pull out in front of me when I wear my lucky fluorescent socks!"

Whatever the magic talisman, users deem it every bit as effective as
medieval indulgences. Anyone who doubts is a heretic to be shouted down.

Here's an anecdote -- I just about got whacked by some dumb f*** on a bike tonight with no light and ninja black outfit. I couldn't see him against the background of other gray and black objects like the pavement. It was heavy overcast but still daylight. In a city with lots of dopes on bikes, it's good to be able to see the dopes -- no blinding lights necessary, but something that isn't funeral attire would be appropriate in low-ish light conditions.

Wearing highly-visible clothing seems like a good idea, though for
vehicles there was no advantage found, in terms of safety, of a more
visible color. There have been advantages found for daytime lights, for
motorcycles, bicycles, and vehicles.

For motorcycles, modulated front daytime lights were found to be more
visible than non-modulated, but there was no study comparing accident
rates. Contrary to what some people on r.b.t. seem to believe, the
absence of a double-blind, case-controlled study, is not a reason to
abstain from using common sense.

Crap, I'm dumping my lights for night riding:


ABSTRACT
• Visibility aid prevalence is low among injured bicyclists.
• In daylight, white or light upper body clothing decreased the odds of a bicyclist–motor vehicle crash.
• In the dark, red/orange/yellow upper body clothing and tail lights increased the odds of a bicyclist–motor vehicle crash.
• Using multiple visibility aids is associated with reduced odds of severe injury in bicyclists.

5 Conclusions

During daylight conditions, wearing white or light coloured clothing on the upper body reduced the odds of a bicyclist MV collision. During dark conditions, red/orange/yellow clothing on the upper body, and use of a tail light increased the odds of a bicyclist MV collision. Among those struck by a MV, the use of more than one visibility aid reduced the odds of hospitalization (severe injury). These results provide evidence that the use of visibility aids has a role to play in reducing the risk of severe injury from a bicyclist MV collision. Conversely, this research highlights the need to consider other injury prevention strategies such as the separation of bicyclists from MVs or reducing MV speed limits.

(2014) 65 ESACAP C 85-96

As for night time visibility,


3.3 The relationship between visibility aids and MV collisions during dark
The crude and imputed adjusted ORs for the relationship between visibility aids and MV collision during dark conditions are presented in Table 5. There were 42 cases and 217 controls who reported bicycling during dark conditions at the time of the crash. The crude estimates indicated that reflective clothing (OR 2.05; 95% CI 1.01, 4.18), any reflective articles (clothing or other) (OR 2.55; 95% CI 1.29, 5.04), red/orange/yellow (OR 4.15; 95% CI 1.17, 14.8) compared with black front upper body clothing, fluorescent clothing (OR 3.09; 95% CI 1.07, 8.94), using a headlight (OR 3.09; 95% CI 1.48, 6.44) or using a tail light (OR 5.28; 95% CI 2.12, 13.12) all increased the odds of a collision. Due to the small number of cases in this analysis, adjusted estimates could only be calculated from the imputed data. With the imputed data, only the estimates for red/orange/yellow (OR 4.11; 95% CI 1.06, 15.99) front upper body clothing compared with black, and using a tail light (OR 2.54; 95% CI
1.06, 6.07) remained statistically significant.

Don't use a tail light!


hmmm. For us Cibie & Soubitez glass bulb w/side dynamo
riders wearing mostly black, and a red mudguard reflector,
crashes are statistically insignificant. Good.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971