The first two are probably more literal than you're interpreting them at first glance. E.g. imagine taking a bike and putting a literal treadmill in it to replace the pedals/seat. It's a (niche) thing separate from a treadmill and definitely moves. In the end I think you're right but your conclusion "it's just a variation of a bike" really applies to all 3, hence "${thing} bicycle" instead of something like "electric suitcase".