Say someone commutes to and from work on CaBi on weekdays, for about 10 months of the year. (Fewer people ride on CaBi in the winter months.) That would be 400 trips. Based on the overall accident rates, that person could follow that pattern of usage for over 560 years with odds of getting into just a single serious bike crash over that time period.
Meanwhile, the lifetime odds of a car occupant dying in a car crash are 1 in 492, as of 2010. The odds of dying from any motor vehicle incidents are 1 in 112, over a lifetime. The chances of dying from heart disease or cancer are 1 in 7. So I’d be more worried about eating all that refined/added sugar and being inactive, than I would be about riding on a bikeshare bike.
http://www.nsc.org/news_resources/injury_and_death_statistics/Documents/2014-Injury-Facts-43.pdf