"Evidence that casts doubt on helmet efficacy" states "Helmet laws in Australia, New Zealand and parts of Canada [15] have resulted in the great majority of cyclists wearing helmets, but there has been no reduction in rates of head injury relative to cycle use. An analysis of enforced laws in these countries found no clear evidence of benefit [16]." Citations 16 is whether mandatory helmet laws improve public health.

The big problem with this and many sources of information on bicycle helmets (pro or con) is that they often mix evidence that is looking at very different questions. For example, a question of whether a helmet use is associated with fewer serious concussions, say, in a crash below 20km hr is very different than whether mandatory helmet laws decrease public health by decreasing the number of active cyclists.

So what, you say, this article is convincing. Well, no it's not. It's a narrative review with no critical evaluation of any of the evidence quality, it mixes levels of evidence as if they're equivalent (which they're not), and provides no apriori statement of a clear hypothesis and so mixes studies that appear to be designed to answer very different questions. There is a clear partisan position here as well. Which is fine, opinions are like *******s, everybody has one. But there's an onus on an author to use transparent and clear methods when putting forward an opinion. This author doesn't: the work is unconvincing, welcome to the interweb.