Safety is definitely important but I have a hard time lining up this advice with how I ride my current bike. I ride downhill at up to 40 mph and my brakes, frame and shock work fine. On my mountain bike, I jump off 6 foot drops regularly. Maybe it's a matter of wear and tear over time being greater because your average speed is higher? I have a hard believing it's the added weight of the motor and battery either since I'm 50 pounds heavier than my brother in law and we have swapped biked a few times with neither bike having issues.