With balance issues, you should definitely look at a trike. Lots of choices at https://www.electrictrike.comRich, a senior in this case is 75 years old. My balance and strength have noticeably decreased in the last 5 years. Yes, at 67, I was skiing double black diamond and riding aggressive single track, but now, not so much.
David, I'm not so sure about saddle height being the predominant factor. I generally have a 33 inch distance from the bottom of my pedal to the top of the seat, for any frame size, or any wheel size. A 20 inch wheel vs a 28.5 inch wheel, will be 4.25 inches closer to the ground. Subjectively, I feel it is confirmed by experience. My 20 inch Dahone (2.2 inch tires) is much easier to flat foot when stopped, than my 28.5 (2.2 inch tires) inch MTB, with both set to a 33 inch seat height, just mho.Small wheels aren't able to roll over, or through, obstacles as easily because the angle at which they make contact is steeper.
Putting both feet on the ground is determined more by saddle height which shouldn't be linked to wheel size.
As always, try before you buy. I enjoyed my years riding small-wheel bicycles… and miss them now that they're gone! (Or, maybe, just miss being young which is decidedly 'gone'.)
… David
I have 5 ebikes and 1 e trike. My trike hits about 24mph, has 4" fat tires, and is a recumbent tadpole. It's far from an old man trike. My speculation is based on watching the reviews on this site. Watch a bunch. I think you'll see a comment about stability in a good percentage of them.oooh, that hurts! lol, not ready for a trike!!! We've had Dahone foldables for years, when we lived on a our sailboat, and had no problem whatsoever with stability. In fact, our experience with many road, mountain, foldable, hybird and the Dahones, is what prompted my question. We currently have 7 bikes between us, including a Terratrike, but am selling all and moving to e bikes, because we hate the hills. You will too, when you hit 75, lol. Have you ever tried a 20 inch mini bike, or or you just speculating from what you have heard?