There have been a notable number of adults coming into the bike library looking for a bike for a 12-17 year old, usually male, because they want them to learn to ride. Typically, the adult is a mom or foster parent. While I haven't done a scientific survey of the situation, my anecdotal impression is that these are kids coming from single parent households. I don't really draw any concrete conclusions, just an observation. But I do have some general theories.