While shifting gears in manual mode for instance from "D" to "M" or from "5" to "6" the transmission shifts instantly. Would this create an abnormal load on the main drive belt over time that might shorten its life. I only use "M" when on the interstate going a steady high speed. Would this explain why some bikes still have their original belts so much longer then others. I don't use overdrive when RPM drops below 4,000 for fear of lugging the engine.