Okinawa has two main urban areas: a small one in the north at Nago, and a much larger mini-megalopolis that stretches from the capital, Naha, to Okinawa City (formerly known as Koza) which borders the enormous U. S. Kadena Air Force Base to the northeast. The road between Naha and Nago is Route 58, and the parts near Naha are clogged with traffic and should probably be either avoided or zipped through as quickly as possible. However, once you get a bit north of Naha it does have pretty coastal scenery. In retrospect, I'd recommend cycling it, but be prepared for traffic.
If you're used to cycling long distances and don’t necessarily need to cover the entire coastline, Okinawa can be done in as little as two days: one day for the loop up from and back to Nago (though it might be hard to work in the Motobu peninsula northeast of Nago, unless you did that quickly the day before when you arrived in Nago, or as a loop before going down south), and another loop down from Nago and around the south shore. I chose to do it in three days, leaving one entire day for a leisurely ride around the south shore with time to see the important sites relating to WWII; obviously this is best done as a day-trip from Naha. Note that the dotted line around the Motobu Peninsula does not mean it's not recommended (it is: the aquarium on the old Expo '75 site is the most popular tourist attraction in northern Okinawa, and there's also an Oceanic Culture Museum), only that there are no pictures of it here since I didn't get to it on this trip.
Your main concern will be that northern loop: it's around 150 km due to the ruggedness of the northeastern coast. From Nago to the northern tip is a straight shot up the coast on a level road, but the eastern coast will eat up lots of time and energy. The problem is that there's nothing up there, meaning very few places to stay (and they may be closed during the non-tourist months). So unless you're camping (and since there are no official campgrounds in the north, this would be unofficial camping), be sure to arrange a stay at the few accommodations in advance. If you're doing the loop in one day, you can overnight in Nago again, and that would allow you to leave as much of your gear as possible in your room in Nago and travel as light as possible. The things to remember are:
(1) LEAVE EARLY. Time will always give you more options.
(2) TRAVEL LIGHT. Take as little as possible - but make sure that includes your bike tools and pump; there are long stretches with few or no places to help you if you get into trouble. Traffic is also light.
(3) Before that eastern coast, STOCK UP ON DRINKS and take some emergency food as well. "Nothing" includes very few vending machines; like roads on Hokkaido, you go for long stretches with no source of food or water at all.
As noted in the "Nuts & Bolts" section, if you're not sure you want to do that entire northern loop, there's a dodge: cycle up on the level road, go around the northern tip and then almost immediately backtrack to the west coast through the hills on local Route 2 and return to Nago. That will give you the prettiest section at the north and a little bit of the east coast wilderness, and it will be MUCH faster than trying to do the entire loop.
