Overall plan is to use three well defined cycling routes to circle through island hopping, starting and ending in Onomichi. This loop is 222km of riding plus a couple of ferries. Fifteen islands in total.
This is topped and tailed by a number of days to do non-cycling exploring.
Some small adjustment may be required depending on accommodation availability.
28/9 Fly to Hiroshima using ANA or Japan Airways (via Tokyo)
29/9 Arrive Hiroshima. Exploring Hiroshima
30/9 Exploring Hiroshima
1/10 Train to Onomichi, collect bicycle, ride to Kamiura on Omishima Island (40km)
2/10 Ride to Yoshiumicho Saiwaishinden on Oshima Island(45km).
3/10 Ride to Imabari (18km) then ferry to Okamura on Okamura Island, and ride to Mitarai, Osakishimo Island (8km)
4/10 Take the ferry from Mitarai to Osakikamijima Island, ride to the northern end and then take the ferry to Takehara (22km cycling, two hours of ferries)
5/10 Day to explore Takehara (salt production, sake production and more).
6/10 Ride to Onomichi (39km), return the bikes then train to Hiroshima or elsewhere.
7/10 Explore Onomichi
8/10 Travel to Hiroshima
9/10 Explore Hiroshima
10/10 Fly home.
11/10 Arrive home
Need to be careful that the rental place is open on the days we want to pick up and drop off! Pick up Thursday, drop off Tuesday (or Wednesday).
I have booked with https://kisocycle.com/ They have Cannondale Trail Neo 4 ebikes.
Backup Options:
Onomichi Base which has a very large range. My preference would be the Riese and Muller Tinker belt drive 20" bikes which have rear rack, Bosch motor, hydraulic brakes... very suitable for ¥36,000. Availability to be confirmed, bookings open in May. Tuesday and Wednesday holidays.
The Red Bicycles Onomichi store. They have ebikes with the option of rear racks for ¥35,200. Wednesday and Thursday holidays.
Giant have a shop right at the ferry terminal. They do ebike rentals and look to have a good range. You can only book two months in advance. No rack rental. Tuesday is their holiday.
Better Bicycles a a big range of models including several with rear racks. Wednesday holiday.
The individual segments are all in a RideWithGPS collection. More descriptive information for each day's riding is on this site (look under "The route in detail")
I expect to use an Ortlieb handlebar bag (using the quick attach mount), a pair of Ortlieb panniers. and maybe a little saddle bag.
Yes, there are tunnels. Given the low traffic volumes and generally cautious behavior of Japanese drivers, it is common to just ride your bike through tunnels like you are a vehicle. I would not recommend this without a tail light and high-vis top layer. HOWEVER, every tunnel has a wide pedestrian path, so it is OK to get off and walk that. Most tunnels are only a few hundred metres long.
Here are the averages for some sample locations