I was going to ask if it falls off when he shifts, or any old time, but it appears that the RadMission is a single speed bike with no derailleur.
I see that radpowerbikes.ca has only one chain for sale, and the description is:
The installation and adjustment part could yield some useful info.
I see that radpowerbikes.ca has only one chain for sale, and the description is:
Quote3/32-inch derailleur chain. Cut to length.Also, a Radmission chain tensioner replacement guide, at https://support.radpowerbikes.com/Maintenance_and_troubleshooting/Shifting_and_drivetrain/RadMission_chain_tensioner_replacement_guide
Compatibility - All ebike models EXCEPT RadWagon
For customers who own a RadWagon (all model years), please contact us here.
The installation and adjustment part could yield some useful info.