> For some reason they seem to think it will work when the book is electronic and small enough.

Do you mean a stationary exercise bike?

I don't read books on those because I am usually sweating and I don't want to get that on the book. Also, most paperbacks are pretty springy, so sometimes I need to have one hand holding them open, or some kind of clip system on the bike.

iPads or Kindles don't have these problems, so I can certainly imagine using them instead. I don't, probably because of an irrational aversion to getting anything from the grungy gym on my personal devices.