This is my first post, and this topic has probably been covered already. Sorry if it's repetitious. My previous ebike was a custom frame with a Panasonic motor. I recently got a bike with a Performance Line Speed motor, and had the "general feeling" (sorry, I know that's vague) that the motor wasn't supporting me as much as the Panasonic. I definitely had to stop to catch my breath more frequently (I ride an ebike because I have heart problems). In addition, there were intermittent "surges of power" (all of a sudden, the bike zoomed forward), usually when I was in a fairly low gear and fairly high motor support level. I exchanged the motor for a Performance Line CX, and the level of support seems better than the Speed (although still not as good as the Panasonic). don't mind the fact that the motor doesn't supply power past 20 mph. With the CX, I still experience these "power surges," although not as often as with the Speed. This never happened on either of my previous ebikes (a Bionx conversion and then the bike with the Panasonic motor). I'm sure that others have experienced this -- am I doing something wrong? Is this preventable? Thanks, and my apologies for the long post.