saw a guy go down Saturday. was riding on a recently plowed paved rail trail. he got on ahead of me & stayed ahead of me until I caught up at some road crossings. he was approaching one & lost control (not sure why) & fell on his side. as I passed him I cud see he had nice wide knobby tires (but no studs). he was fine w a big smile on his face. I had been video taping but not at that time