Just off the top of my head...

Why not also convert your Pops bike into a 3-wheeler and put an electric starter on it, so he won't have to "kick" start it? Or just add an electric starter to your Pops bike...

Although, with his leg problem, he may want the 3-wheeler...That's what I want, especially after some "lolo" ran us off our bike back in 2015, I never made it back home till after a MONTH of hospitalization AND PT in another care facility, with 2 rods in my left leg, 12 screws, and 49 stitches...Yeah, the 3-wheeler is lookin' gooood...lol