Bike by steventilly
Kos is a great place for bicycle hire - there are hire places all over the place and lots of bike parking spots too. There's a proper cycle track that runs from Kos Town, along the seafront, past the (new) marina, through Psaladi, past the water park and eventually onto a really quiet road that can take you right round to Empros Thermes. We didn't go that far, we turned back at Agia Fokas, but it was a great day of gentle biking. We found a great taverna (Nikos & Kontessa) on this ride, between Psaladi & Agias Fokas.
In the other direction, you can cycle from Kos, through Livadi and Selveri to Tigaki and on to Marmari. This is on a quiet back road with hardly any traffic, which hugs the coast for the whole way.
Bike hire is really cheap, the bikes are good (18 speed "all terrain" bikes) and they come with integrated locks. Many tavernas and private beaches along the track to Psaladi have bike parking facilities.