Maintenance of your R2 should be done after every ride in wet/salty conditions. If you never ride in the rain or in salty conditions then you should only need to maintain your R2 on a monthly basis.
A full maintenance of the R2 consists of:
Ensuring all of the hardware is secure
Lubricating and cleaning bearings
Cleaning the grip tape
Removing any salt or water residue
Watch this video for how to properly maintain your R2