“For this bike, speed is a problem. 14mph is not a useful speed.”
I have an e-bike. 12 mph is a nice pace for touring on good trails.
When I used to road bike more, 12 mph was about my minimum. I wasn’t a great cyclist but I’ve averaged 18 mph for 100 miles a couple times. 22-24 was my general flat ground speed.
12-14 is pretty slow
Even for strong cyclists, 14mph is a good average speed with traffic or hills.