1. Adjust The Limit Screws
With no cable tension, the rear derailleur will be at rest - this is required to adjust the limit screws. To do this, ensure that the derailleurs upper jockey wheel is positioned directly under the smallest cassette sprocket. If it isn’t, turn the screw marked ‘H’ to adjust its position. Turn it clockwise or anti-clockwise until it is directly in line with the smallest sprocket. Similarly, adjust the largest sprocket by moving the derailleur to its furthest position and ensuring that it is under the largest rear sprocket. Make adjustments to the screw marked ‘L’ until the top jockey wheel is directly in-line with the largest sprocket. Let the derailleur return to its rest position under the smallest sprocket. Finally, turn the rear derailleur’s barrel adjuster fully in, then out for two full turns. This provides you some leeway for further adjustments.
2. Adjusting Cable Tension
To do this, it is most important to ensure that the rear shifter is fully downshifted i.e. at 1. Use a cable tension puller tool (or if you don’t have one - just pull on the cable with whatever you have), and place tension on the inner cable. As you reach full tension, the pull-force on the cable will start to try to move the derailleur inwards i.e. towards the second sprocket. At the point where the jockey wheel begins to twitch to do so (remember to not let it move more than .5mm), put the cable anchor pinch bolt up tight. The derailleur will relax the .5mm, leaving it directly under the smallest sprocket with the optimum starting tension on the inner cable.
3. Final Adjustments
To do this, you will have to have your bicycle off the ground - preferably on a stand. First, rotate the cranks forward and click to shift one gear on the rear gear shifter. You should have a clean movement of the rear derailleur inwards, shifting the chain onto the adjacent sprocket. If so, keep shifting one sprocket at a time all the way up and all the way back down. If the shifting has a lag, or is not precise, you will need to use the barrel adjuster to add or remove tension as required. To make this adjustment, you will need to shift the chain onto the middle of the cassette 4th or 5th sprocket and make the necessary adjustments with the barrel adjuster to ensure the jockey wheel lines up with the sprocket. Never adjust more than a quarter turn in any direction without checking the effect on shifting first.