Earlier quoted context omitted.
Odd that you say this about helmets. It only takes one mistake, one cyclist not paying attention, one mechanical fault, one swerving car or an obstacle in the road - and you'll be landing face first into the tarmac wishing you wore a helmet. 185 cyclists died last year in the Netherlands [1]. I wonder how many of those weren't wearing a helmet. I also found this interesting article [2] going into a lot more detail on…
Typical bicyle helmets don't help much with a face-first landing on the tarmac, your chin takes most of the pounding. I can confidently say that from repeated ... 'experiments'. In contrast, a motorcyle helmet that also wraps around the chin would be of great use in most bicycle accidents. 185 cyclists died A more interesting statistic would be: how many of those deaths would have been prevented by a bicycle helmet?
If we assume that this Canadian study would apply as such to Netherlands:
http://www.cmaj.ca/content/early/2012/10/15/cmaj.120988.full...
the figure would be
(71/129)×185×(100-65)% = 35 of these people would have not have been killed.
Of course, the figures are probably not quite right for Netherlands. For instance, in Canada a majority of bicycle fatalities involve another vehicle, whereas where I live (Finland), this is not true because we have separate bike/pedestrian paths in many places. Like the Netherlands. This actually increases the effectiveness of helmets, because fewer of the accidents are about being crushed by a big vehicle, and more of them are falls.
And the physics of falling off your bike are not that different and the ground is about as hard in Canada as in Netherlands.