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I can't recall ever reading a bicycle safety study that had any level of statistical rigor.

I'd be interested in seeing who funded the research (the article is paywalled though). It seems there is a never-ending stream of money to fund research of dubious quality, as long as the finding is bike helmets good, bike lanes good, or VC bad.

If you don't have the data to come to any meaningful conclusions, then you simply don't have the data. Either get good data, or give it up; it is simply irresponsible to attempt to come to conclusions that the data don't support. It's almost as if they had decided beforehand that helmets improve safety...


We don't need no stinkin' facts.

J. M. Graves received fellowship support from National In- stitute of Child Health and Human Development during the course of this research (PI: Rivara, T32 HD057822-01A2). This work was also supported by the Harborview Injury Prevention and Research Center, University of Washington, the National Trauma Data Bank, the Quebec Trauma Registry, and the Vancouver Trauma Registry.

Happy to send anyone the article, too.

Is she suggesting that the decrease in injuries in bikeshare cities might be caused by a decrease in ridership rather than a decrease in injury rates?!?

In my book, that wouldn't pass the laugh test. Aren't there a gazillion studies out there showing bikeshare increases ridership?

Reading the article more carefully, the researcher is saying that instead of bikeshare cities having a decrease in ridership, non-bikeshare cities might have increased ridership faster than bikeshare cities. Again, this doesn't pass a laugh test.

There are so many problems comparing between cities, notably that bikesharing typically comes with other bike-friendly policies (e.g. lanes, enforcement).

The problem is the decision to derive a policy consequence from the research. The author is correct that we do not know for certain what happened to ridership. Ergo, the proper conclusion is that there is no obvious direct policy application from this research, other than the need for better data on ridership. That does not mean the research has no value, as someone might well find that info on the change in injury mix is useful for some purpose the authors cannot discern. It is unfortunate that some researchers seem to believe that a direct policy conclusion is needed to justify their research - that leads to unjustified recommendations, as in this case.

+1 ACyclistInTheSuburbs

I agree, too, and would offer one additional comment. To wit, the assumption that helmet use by bikeshare users would have mitigated the population of injuries sampled in this case is invalid, for reasons often discussed. Rather than assuming this to be the case, the investigators should have made it part of their hypothesis.

A better study would have distinguished helmet-mitigable injuries, i.e., skull fractures, from other injuries, independent of severity. This also undermines the validity of the recommendations.

Smedley, I think you would have a hard time coming up with a rigorous definition of a "helmet-mitigatable injury." The evidence for the effectiveness of helmets is pretty weak.

I suppose if you are going 5 mph and fall sideways into a curb. Onto your head. At a 90-degree angle such that the helmet doesn't cause much in the way of extra torsional to be forces exerted. Is that all possible?

This just in: 100 percent of cyclists taken to the hospital after an incident were injured!

Contrarian, I think looking at skull fractures and epidural hematomas would at least target what helmets are believed to mitigate. Of course that would likely reduce the sample size to something pretty unreliable.

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