If you're going to be trail riding in the mud, a fixed fender can clog and leave you stranded. That's the #1 reason I use these fenders from FF. However, I've had two of these snap on me over the years. One from a 16mph nosedive on asphalt (error 16) and the other from a mild board rollover. Hopefully this new version will be better at taking some abuse. Other than that, these have been great!