Thursday, May 28, 2009

Weather a safety issue.

www.bikesafer.com,
Our companion site pays short shrift to weather problems, as the studies (Hurt, Maids) didn't seem to find that weather is a factor in bike crashes. As soon as I got a mile or so from home on my post-publication ride, it started raining really heavily, and I found myself doing all the usual things - adjusting equipment so I could see better, considering my conspicuity in reduced visibility and accelerating and braking easier. When I stopped by Terry at Motorcycle Maddness, he reminded me how good rain was for practicing these skills.

I think I figured out why rain doesn't show up as a major cause of crashes in the study. In the US, bikers are mainly recreational, and often ride plans are canceled if there is rain. One local riding club has a "50-50" rule, for instance, with automatic cancellation of posted day rides if there is a 50 percent rain chance or temperature under 50. In my own experience, when caught on the road by bad weather, I often tweak the itinerary or schedule to avoid storms. All very sensible, but this probably causes much fewer miles to be ridden in the rain than in good weather. As the studies are driven by actual crashes, fewer rain miles will tend to under-represent rain-related crashes, even if there are more crashes per rainy mile ridden than for dry miles ridden.

In the case of Europe, where there are much more commuter miles ridden, I'd imagine that commuters use other means if they can, like carpooling or public transport, when it rains. Also, as a practical matter, if a rider doesn't use extra precautions during rain, it won't be long before Darwin reminds him with bike-dropping event. In the wet, riders tend to have slickers on, and the road surface has a lower coefficient of friction, so as long as you don't hit an immovable object, your chances of surviving the drop are maybe a bit better. So you might survive your initial rain drop, but you will be much more careful in the future. To some extent it is a self-correcting problem.

In this case, bikesafer.com will be going with Terry's biker gut, ignoring the studies, and adding more pages soon on riding strategies in adverse weather.

Maybe there is some way the new, long delayed US study can control for the rain factor and come up with reliable numbers on weather as a crash causation?

Sunday, May 24, 2009

Video on how not to ride pillion...

2-second rule not enough for highway speeds

My friend Hamayar, who hails from Wales, sent me this link, from the UK Survival Skills site. The site is pretty cool, although some of the articles need translation to driving on the right. The referenced article makes the point that the two-second rule provides a following distance in which the bike sometimes can't stop in time to avoid a vehicle stopping in front. His calculation is basically that the two second rule is insufficient at speeds of 60 mph and above, probably because the distance covered during reaction time is greater at these speeds.
Food for thought, epsecially for group riders on the highway.
My take is that the calculations aren't conservative enough. He uses 0.9 G of braking force for the motorcycle braking force, while the Quebec Promocycle Foundation did a study that found more like 0.75G for a bike without ABS but an experienced and skilled rider. The Quebec site has more on rider reaction time also, which makes the half second response time look a bit skimpy. The average seems to be consistently a bit over the half-second, and is actually worse for women. The average reaction time looks more like 5.3 seconds, and a large number of the braking intervals sampled were longer than this average.
The Quebec study suggests that both the assumptions the Survival Skills author used were skewed toeards underestimating the problem.
The lesson is clear. The two second rule is an absolute minimum at speeds up to 45 MPH - or maybe less - and seems to be less adequate at highway speeds or greater.
Has anyone got a calculator who can apply the Quebec numbers to the Survival Skills computations? I bet that would be a scary set of numbers.
In the meantime, we should probably rethink our following distance calculations for highway speeds, and add a liberal (or conservative) dose of extra following time to the two-second rule. For group riders and lead riders, perhaps something to mention at the next safety briefing. Looks like inexperienced riders might want to add even more time cushion.
In the meantime, y'all enjoy the Promocycle and Survival Skills websites.

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Saturday, May 23, 2009

Welcome to ET's Bike Safer Blog

Bike Safer and its blog is up. Welcome and feel free to post your comments, additional info, crash stories, handy links, and errata.
I've been working on this for six weeks, today some beer, and celebrate with Special ED and friends. Tomorrow I am off on my planned ride to Montreal, which has been delayed by HTML. I won't have my laptop with Dreamweaver, so it is the blog for now.

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