The fundamental problem with center mounted motor drives is that if you are not in the correct gear, the motor is very in-efficient and you’ll get very little assistance! Like starting your car in 4th or 5th gear, you’re not going to get very far. The systems do not take into account the habits of the rider. Most of us are not elite athletes, and therefore we usually are in the wrong gear when riding, and mostly, we are in the wrong gear when we come to a stop. We all know the feeling of starting out in a high gear, and if your ebike has a center mounted crank drive solution with a derailleur system, the motor is not going to help you much if you are in the wrong gear!
Answer by Richard Thorpe - Gocycle's designer