Don't need a book for that . . .
Will be 80 this year, and spouse will be 77.
We still ride a tandem regularly.
I rode 5,600+ miles last year, that includes tandem and single bikes.
You need not to engage any mental effort checking out graphs and words.
You need to engage physically and get on your bike, meet other folks and ride!
Join the local bike club . . . and have fun.
Pedal on!
Rudy/zonatandem