The Great Ocean Road is an excellent tour on a bike. Just be aware there is a bit of traffic around Geelong if you choose to depart from there. DO NOT try to ride from Melbourne to Geelong down the western side of Port Phillip Bay - it is flat, open and windy. The main Princes Hwy is a freeway - bikes may still be allowed on it, but it will not be a pleasant experience at all. An alternate start may be to catch the Met train to Frankston then ride down the Nepean Hwy and The Esplanade to Dromana and Sorrento to catch the car ferry across the Heads. Then ride through to Ocean Grove, Barwon Heads and Torquay to join the Great Ocean Road.
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don't start off on a summer weekend - the section from Geelong to Lorne can be very busy then. It's fine at other times of the week. Beyond Lorne and especially beyond Apollo Bay the GOR is a lovely generally quiet ride.
Really good campsites include the caravan park at Aireys Inlet, the one at Kennet River is good also. Past Apollo Bay near Cape Otway, Bimbi Park is an excellent bush caravan park. There are camping areas at the Aire River mouth and at Johanna Beach. When you get to Glenaire there is a gravel road off to the right (the Old Ocean Road) that is really worth taking to avoid a steep climb by taking a nice contoured road up a valley. Lavers Hill is a big climb in a series of rises and falls - no real way to avoid it. Down at the coast again near the Port Campbell coast, Princetown has camping at the recreation reserve by the river, but also a handy caravan park up in the town on the hill, next to the store and right across from the very nice pub.
The Port Campbell coastal cliffs are spectacular. After Peterborough make sure to do the route past the Bay of Martyrs - very scenic and keeps away from the faster traffic on the main GOR. There is also a possible side trip into Childers Cove that is a very peaceful spot for lunch. Warnambool is a good place for a short beach break, with an excellent maritime museum at Flagstaff Hill and art gallery in town.Riding to Port Fairy do the deviation around Tower Hill and through Koroit...
but don't miss out on Port Fairy - a beautiful and characterful historic fishing port. Another larger deviation is to go to Mt Eccles National Park for the volcanic features. If you chase up a few back tracks through the national park it is possible to ride through to Heywood on very quiet roads. Failing that the Princes Highway to Portland is really a reasonably quiet road. West of Portland, Cape Bridgewater is a lovely small beach hamlet to visit with a delightful beach-side cafe. Quiet camping is possible at the Bridgewater Lakes Boat Club with a sheltered site, tables and a toilet nearby. The road to Mt Gambier via Nelson is a good route - however we found it had a lot of trucks transporting wood pulp to the port at Portland, but the truckies were always very considerate of us - we reckon some of them probably passed us 4-5 times that day.
Beyond Mt Gambier there are some wonderful coastal towns about a day's ride apart - Beachport, Robe, KIngston SE, then a longer haul to Meningie. We camped partway between, along the Coorong at Salt Creek Roadhouse. It has a small camping area and the owner of the roadhouse was a marvelous, welcoming chap, talking to us in the premises, where we had dinner and a few beers, until well after 10pm. After Meningie there are some more choices possible to get to Adelaide. We crossed the Murray on the punt at Wellington then rode through Langhorne Creek, Strathalbyn, Macclesfield, Echunga and Stirling, to drop into Adelaide from Crafers on the bike track along the old Mt Barker Rd.
This shows the route of the journey we travelled (well, the last section from Oodnadatta to Alice was not completed).
Have a great time on your tour.