Hi , KNOW THIS HAS BEEN COVERED, BUT TOOK COVER OFF TODAY TO GIVE A BLOODY GOOD CLEAN AND MEASURED FRONT SPROCKET NUT AND IS ONLY 9MM , IS IT RIGHT NEW UPGRADE IS 12MM? WAS LOOKING FOR THREAD ON HERE FOR BEST PLACE TO GET ONE ( MUST BE BLIND)CAN ANYONE POINT ME IN THE BEST DIRECTION ? HAS BEEN FINE FOR PAST FEW YEARS BUT RATHER CHANGE NOW . CHAIN AND COVER ARE ALL CLEAN AND RE-LUBED UP NOW ;-)