The Aluminium Strida freewheel with sealed bearings is rust proof and water resistant. This is the replacement freewheel for Strida models, 5.0, Lt, Sx, and EVO.
To replace the Strida Freewheel the rear wheel needs to be first removed from the bike. The freewheel is removed from the wheel using a tool that fits in the center of the freewheel. The tool I use is a Park Tool U.S.A. model FR-6. Your local bike shop will most likely be able to help you with this.