Cycling in Ibiza

I was in Ibiza last year. I didn't do any cycling but did purchase a few items from a bike shop in Santa Eulalia - "Bicicletas Kandani" I think they were called and they seemed to stock some decent bikes and kit which was available for hire. My impression was that Ibiza is biased more towards mountain biking rather than road cycling, that's not to say you couldn't ride on the roads, just that most of the cycling activities had an off-road feel to them. One things for sure, it is not Mallorca.
Formentera is a nice day out but take plenty of cash, it is extortionate. I'm not sure how easy it would be to get a bike across as the ferries seem to be quite small, more of a pleasure cruiser type vessel than a ferry.The island is pretty small so you should be able to take it all in comfortably in a day with plenty of refreshment stops if you feel the need.
Hope this helps.