The problem with ALL discussions of head injuries, including bicycle related ones, is that folks often fail to separate numbers from rate. Bicycling accounts for a fair number of head injuries, but that because so many people bicycle. The actual rate of head injury is fairly low, and is much lower than many other sports. If the same number of people played hockey as bicycled (at the same mix of skill levels) the number of head injuries would boggle the mind.

So, it stands to reason that as bike share programs increase the number of urban bicycle trips, the number of injuries (all kinds) will rise. However, it's entirely possible that increased numbers of bicycles on the streets will condition drivers, and the total accident rate will go down. Depending on how it plays out, we can see an increase in the numbers, and a decrease in the rate at the same time.