I bought my son a used Mongoose Xr-75 as he had outgrown his 24" bike. It looked nice, when I test rode it though, it would make a rubbing sound, and even a vibration only when I stood up to pedal on it. When I sat on the seat and pedaled it was fine. I assumed it was because I was 210 lbs and bought the bike. My son tried it out yesterday and it still made the noise/vibration (but only when standing up to pedal) and he is only 140lbs.
Is there a way to fix this?
Is there a way to fix this?