My nice bike has metal Berthound fenders. These things are solid - you feel like you could sit on them. My errand bike has plastic Planet Bike fenders with flimsier stays compared to the hardware found on more expensive metal fenders. My biggest annoyance with fenders is when the rattle or get out of alignment. My errand bike gets carried up and down stairs, gets shoved in and out of doors, and locked to poles and racks every day. I'm hoping people can share some good DIY methods of boosting the stability of inexpensive plastic fenders such as Planet Bike, such as replacing the fender stay hardware.