It depends on how tough your pants are. I had some heavy ripstop pants roll down into the chain, and they went all the way around!!! It destroyed them, but didn't tear them enough to release me from the chainring. Soon after, after almost 10 years of riding exclusively fixed, I bought a geared touring bike (also vintage), and infrequently ride the fixed gear now. Whether I ride much FG in the future depends on where I move this summer.