Ok, I am riding a bargain basement EZ-1 by Sun. I know it weighs 35 lbs, and I weigh 222, but when I am riding with my family on their used Trek mountain bikes, they literally coast past me while I pedal furiously. Is it just a weight issue, or does it have to do with the wheel diameter, or do I need my bearings replaced? It is embarassing. I'm ready to buy a cheap upright for family jaunts.