Bike rental in Onomichi (Shimanami Kaido)

This is not a question but a suggestion (hopefully helpful). If you want to rent a bicycle in Onomichi for cycling the Shimanami Kaido I can suggest Better bicycles (https://better-bicycles.com/).
We used then today because there was no more avaibility with the companies mentioned at this website. It went very well. The bikes are high quality, the chap at the office is very sympathetic and his advice is sound.
They don�ft do bike returning, but you can put it on the ferry.