Our Suntour / Simplex jockey wheel kit….10 tooth…fits most Suntour rear derailleurs and early Simplex rear derailleurs. New Shimano jockey wheels will not fit the old Suntour or Simplex 5 speed derailleurs.  Lovecitycycles conversion kit has new correct size adapter bushings, for Suntour or Simplex rear derailleurs using the 8 mm jockey wheel bolts, and matched them up with the new 10 tooth pulleys. Our kit will fit most Suntour ( AR, ARX, Vgt, Seven, GT and most other Suntour 10 tooth derailleurs.  They will also fit Simplex Prestige, LX, SX, and most early Simplex derailleurs.