Setouda port to Imabari in one day by bike

I want to do part of the Shimanami Kaido and will take the ferry from Onomichi at 7.10 to Setouda. Will pick up a rental from there and start cycling. Is it doable in a day cycling with stopping to sightsee and take pics?

I have not actually run, but here is the approximate time when running on a sports bike.
https://train-cycling.com/shimanami-time-required/
The time will also vary depending on how often you cycle and what type of bike you have.
By the way, I go shopping on my mamachari (city cycle) two or three times a week.
I cycle about 7 km in about 40 minutes. (For downhill)
Also, the time varies depending on how long you stop by the tourist spots.

Difficult to answer. I personally can easily cycle 100 + km/ day. But it depends on your fitness level, tge rental bike, how often you stop, which route you take.

I strongly recommend to NOT take the direct route through Omishima, Oshima and Hakata. It is much more scenic on the secondary route. But also longer.

http://bicycletraveljapan.blogspot.com/2017/11/part-10-day-48-49-ridin...

Also cycle before in your home country a similar / longer distance a few times so you know you can do it. Then you can enjoy the experience.