Naturally bicycles are allowed on all car ferries in Croatia. The surcharge depends on the length of the journey. For local car ferries, Jadrolinija charges start at €2 for a short trip like Drvenik-Sucuraj.
Jadrolinija does not allow bicycles on catamarans except for the new Vida catamaran on the Split - Hvar - Korcula line.
Therefore, there are NO bicycles allowed on the following popular lines:
G&V Lines runs the popular 'Nona Ana' catamaran from Dubrovnik to Sipan, Mljet and Korcula. Here's their policy as stated on their website:
Bicycles are considered cargo and as such shouldn't be allowed to be taken onboard ships sailing on high-speed lines. However, captain has a right to decide (just before departure, based on current situation) if bicycle can be taken aboard and at what cost.
In an email, the company elaborated:
ship is rather small and can't take more than couple of bikes during high season. So, groups of more than 5 people will most probably be turned down if ship is usually full. There is simply not enough room for example for 10 bikes. During winter, however, we can take a LOT of bikes (maybe 50 or even more) because we don't have many passengers and they don't carry any luggage. In summer, EVERYONE is going on board with suitcase . . .
On the "Krilo" line from Split to Hvar and Vis and on the line from Rijeka to Mali Losinj, bicycles are allowed ONLY if they are in a bicycle bag. The charge is the same as the passenger fare.
On the "Krilo" line from Split to Dubrovnik, bicycles ARE allowed. The charge is the same as the passenger fare.
On Venezia Lines' catamarans from Venice to Istria bicycles are allowed up to a maximum of 8 bicycles per sailing. The limit is rarely reached; the surcharge is about €10, payable at the time of booking.