If mom is willing and able, why not?
Friends of ours just quit tandeming . . . they are in their mid-80s; yes, and they had 2 tandems, one for the road and one off-road! For her 80th birthday they bought a new Co-Motion! Heck they are our idols, as we are only in our mid-70s.
Pedal on TWOgether!
Rudy and Kay/zonatandem