Can you take bikes on the island ferries?

All car ferries between the islands of Brac, Hvar and Korcula take bikes. For most of foot passenger ferries it depends of the decision of the captain on the day (due to possible bad weather, too many passangers or similar).

I would suggest you to plan your travel manily by car ferries, although in my opinion, as you are travelling out of season, and ferries will not be overcowded, it is very likely your bike will be accepted on all ferries. Just turn up bit earlier and speak to the crew, they are generally helpful re this matter.

In my opinion all three islands are worth visiting , cycling around them is nice and views along the roads are great. It really depent how much time you have, but if you have enough time yes, visit all three islands.