Originally Posted by
Jeff Wills
OK...
2a. Shop adjustment- with the bike on a rack (or similar), move the rear derailleur with your hand while turning the pedals. This shifts the chain to the second cog.
2b. Stop pedaling, and let go. The chain won't shift, and there should be a bit of slack in the cable because the shifter is still in "high" gear.
2c. Take up the slack in the cable with the barrel adjuster.