The Centers for Disease Control released a report on Monday about long-term trends in cycling deaths.

At first glance you may think “great, cycling mortality is declining!”. However, as previously discussed on streets.mn cause-specific mortality rates are a funny thing. They reflect the sum of the riskiness of an activity, and the frequency of the activity.

Indeed, the most dramatic declines in mortality rates from cycling have come among children, and the authors of the report speculate that “the decline in bicyclist mortality among children might be attributable to fewer child bicycle trips rather than a result of safer road conditions.” Among adults the good news is that recent (since 2000) large increases in the frequency of cycling by adults have not been reflected in higher overall mortality from cycling.

But you can see the rise in cycling show up in the growing proportion of all traffic deaths that involve cycling (Figure 1). This figure implies nothing about the riskiness of cycling. We could see a growing proportion of cycling deaths relative to all traffic deaths merely because non-cycling traffic deaths have declined (which they have, but not as fast as in other countries).

One of the foundational points of demography is that we all have to die of something, sometime. Massive increases in the number of people cycling, the distances they cycled, and its mode share would almost certainly lead to an increase in the proportion of deaths that were related to cycling unless we made incredible improvements in the per-mile safety of cycling. Let’s keep making those improvements.