I googled Stewart Browne just to make sure I wasn't missing something.
As funny as Sheldon Brown was, he didn't have the comedic foresight to register StewartBrowne.com
Originally Posted by
Daspydyr
Try getting a genuine chain lube like TriFlow from your LBS. That is much better than WD40. Your chain also might need a good cleaning. WD40 is more of a cleaner than a lube.
Another problem can be frame flex. Stewart Browne points out that when you accelerate or start from a dead stop that the frame slightly flexes and stretches the cable. Put a drop of lube on the cable where it contacts the plastic protector on the bottom bracket. This is a remote option, but worked for me.
My gut feeling is that you have a dirty chain that needs a good cleaning and a true chain lube.