Many single speed freewheels are pretty low cost in their construction. I had a trials guy (all 125lbs of him) working for me a while back. He would go through a number of these every season. Not from tooth wear but from ratchet skipping. After taking the first few apart to confirm this he just bought a bunch at a time and he was good for the year. His chains would last a couple seasons if they didn't get ground down from his wall work. Andy.