hippy said:DaveB wrote:
Chainline is the imagined line between the front and rear sprockets. The
rear sprocket should be exactly behind the front sprocket so that the
chain runs in a straight line. If you do not have this "perfect
chainline" you will experience chain derailment, possibly like what
you're experiencing now. Check your chainline - measure it.
http://www.sheldonbrown.com/chainline/
hippy
Also check that your derailer isn't causing your chainline to go off at the underside of the chain just as it leaves the rear cog.
Koon