Crossing the epic Shimanami Kaido island route by bicyle is one of the highlights of any trip to Japan. From the stark beauty of the six islands you traverse, to the engineering and architectural marvels that make up the longest series of suspension bridges in the world, there's no better way to cross from Honshu to Shikoku (or vice versa).
Departing from either Onomichi (Honshu) or Imabari (Shikoku) the 70 km ride is clearly marked and is sprinkled with gorgeous panoramas of the Seto Inland Sea. There are also many interesting places to visit on each of the islands, such as temples, museums, ancient fishing villages, beautiful beaches and mountain parks. There are rent-a-cycle terminals (nice hybrids) at both Onomichi and Imabari and at several places along the route; and at ¥500 a day to rent the nice bikes, it truly is the cheapest way to enter beautiful Shikoku!
At 70 kms, start to finish, the whole route can definitely be done in one day, but you'd be missing a majority of the attractions, and probably a bit too winded to really enjoy the unique atmosphere of the islands. Why not spend a night at one of the many guesthouses or ryokans along the way?
One good option is Setoda Private Hostel (Tarumi Onsen) on Ikuchijima Island. It's just off the main Shimanami Kaido route, only 3 km from the impressive Tatara Bridge, right across from the the splendid, and aptly named Sunset Beach. The location, and the fact that it's about halfway along the route, makes it an ideal place to stay. The small town of Setoda itself is also worth exploring before returning to the bike route if you have time.
My wife and I pulled up to the rustic set of buildings after 5 hours of riding on a perfect October day and were warmly checked into our private room by the very friendly owner, Omoto-san. We immediately headed to the perfect beach to enjoy some brews and congratulate ourselves on a day well-biked. Though the Japanese-style, tatami rooms themselves are very basic and a bit worn, the real charm (and value of the place) is contained in the onsen hot spring bath that Omoto-san himself built at the back of the complex overlooking the beach.
As we settled into our respective baths, both my wife and I were graced with huge rocks situated around a hinoki wood room with the sunset filtering through the window overlooking the beach and Seto Inland Sea—about as close to Japanese paradise as you can get! After our baths we sauntered over to the dining room for a huge delicious meal of locally caught fish (both sashimi and grilled) and pork ton-katsu cutlets.
At ¥3,000 per person (¥4,800 with breakfast and dinner) it's excellent value. Though the staff have only a basic level of English, this is probably the most foreigner-friendly place on the route and they do their best to make all feel at home. The hostel was run as a HI hostel for many years and the layout and condition of the buildings show their age. However, what the buildings lack in luster, the place more than makes up for in character and location.
If you're planning to cross the Shimanami Kaido, I strongly recommend taking a slower pace and staying overnight on one of the islands, and it's hard to find a more ideal spot than the Setoda Private Hostel.