At age 77 I purchased an electric pedal-assist bicycle. I recently got a bum knee (meniscus tear) and planned a jump in daily commute from 4 to 10 miles/day. Never any traffic in the bike lane. Hooray! My route.
The bike does not have a throttle. It assists according to my pedaling effort and my setting: zero, weak, medium, or strong. Silent, powered by battery (under the back rack); 350 watt motor in hub. I bring the battery indoors to recharge about every 20-25 miles.
Before buying I was worried it might not make it up nearby hills. No worries. A nearby hill rises 100 feet in 1/3 mile. I peddled up easily at 10-12mph using medium assist. European made ebikes do not assist above about 20mph.
I spent one evening with Google and Youtube learning the basics. Rather than purchase from local bike shops stocking a single ebike, I drove 10 miles to a shop in Redwood City (Motostrano) that had multiple dozen ebikes in stock, and also services them. "Justin" interviewed me for my worries and needs. He arranged test rides of two competing models in the large parking lot behind the store. I selected the A2B Ferber bike. Adding a helmet (nice rain visor), an Abus folding lock (rated 9/10) for $120, and sales tax, I paid under $3000.
On the level I pedal about as hard as I formerly did, but now I go faster in a higher gear. On hills I am now comfortable and explore much more than I did. On the flats without assist I peddle 8-10mph. I normally use the weakest pedal assist. With it I peddle 15-18mph. So, the assist about doubles my speed. It's pretty easy to surge to 20mph. Yipee!
FLAT TIRE WARNING: Within the first 15 miles on my new bike the front tire went flat. Evidently, California thorns are more vicious than German thorns. Motostrano fixed the flat for free. They suggested I purchase "tire liners." $25 got me two, one for each tire. I see that product at California Bike Gear. No problems in the first three years. I wish this had been taken care of during my original purchase. (Watching my flat being repaired, I couldn't help but notice how easy it would be to steal the front wheel. A replacement requires the disk-brake plate, not expensive, but an annoying issue. Lucky for me, my employer has a bike cage.)
At 1000 miles I found myself referring to this bike maintenance forum., my problem. Here's the needed bike manual (that did not come with new purchase.) A video like the manual. The odometer failing; likely needs a reboot. At age 80, I'm still biking to Stanford 2-3 days a week.