Originally Posted by
Bekologist
why a decline in child participation in cycling from the 1970's would skew declining indexed accident rates seen in the last few years is a stretch.
I don't think he was talking about a decline in the number of child cyclists, but rather a change in the mix of cyclists. The more adult cyclists there are, the lower the proportion of child cyclists. Kids on bikes are relative crash magnets compared to adults. Increasing the number of adults riding would decrease the number of injuries/rider because adults on bikes injure themselves less.
A very simplified example:
1,000 children and 1,000 adults ride in an area. In a given year, half the children are injured while only one in 10 adults are. The number of injuries/cyclists is 0.3. The next year, 500 additional adults start riding, while the number of children stay the same. The number of injuries/cyclists drops to 0.26. The next year, the same thing happens, and the number of injuries/cyclists drops to 0.233.
It may not be safety in numbers, but rather a safer mix of cyclists.