If You call an industrial fastener store and ask for a 4mm x 50 (or 5/32" x 2") ROLL PIN. Or buy a M4 (4mm) x55 Hex drive cap head screw and cut off the head … these will fit and probably be stronger. Or… you could call up velorusion, Deens Garage or Bikefix in london - seem to be the best Strida dealers in UK, I find phoning is best … more on www.strida.co.uk