also, anecdotally, just using the forums I subscribe to, almost all (perhaps all, but I am giving a little room for doubt) of the "my helmet saved my life" stories come from folks who were clipped in or whom were assing about on mountain bikes in rocky terrain. Nothing like a typical omafiets rider, then.
No-one in my family has either clipless pedals or off-road tyres.
Indeed, none of us even have tyres that weigh less that 600g per tyre (so high-speed blowouts are unlikely).
It is a classic error of logic to apply the specific to the general.
It is already clear that this (in general) has happened here.
I will read on, but it is not clear to me that child injuries are going to be differentiated from adult injuries. As the normal explanation for the lower speed injuries that children tend to get is that children make poor decisions due to lack of experience, then that would also undermine the validity of the application of the study being applicable to adults.
So the adult omafiets-type rider looks to be the data that is least well represented in the study, yet that is the very category that we are in when not wearing helmets.
To give an analogy to make the point:
In the UK, motoring insurance is based primarily on age.
Age is used as a proxy for experience. A 17-yr old in a car or on a motorcycle is deemed VERY high risk.
For a 17yr old who is a new driver, compared to 50 year old with similar experience, the 17 yr old pays more for the same vehicle being used it the same way. Why? Because 17 year olds crash more. Plain and simple. Even if they are both "novice drivers".
Then take a typical 50 yr old, who has maybe 30 yrs experience of driving, and they might pay a third to a tenth of what a 17yr old pays (the premium multiple goes up as the car gets faster!). Take into account the typical"crash-free" bonus an older motorist has built up, and the differences are even greater. An old chap like me can afford to insure just about anything, but 17-yr olds are notorious for paying more for annual motoring insurance than for the actual car. Indeed, the "youth risk" is so great that most hire companies simply refuse to rent cars to folks under 21, even though there is no law preventing it.
So, to summarise, having already found that speed has not been accounted for in the Australian study, I will be looking for rider type (MTB, road, omafiets) and rider age.
I suspect that neither factor will have been accounted for.
But, of course I can only do that with the full study, so thanks for giving me the opportunity.