If you’ve been on the bike a lot since your spring tune-up, it’s probably time to readjust your shifting. For go-getters who want to tackle this project themselves, here are a few pointers:
For every click of your rear derailleur shifter, the derailleur should move the chain one complete gear change. Start with the chain in the smallest cog. If you click your shifter to move the chain up to the next largest cog on the rear and it does not go up or hesitates before moving, you need to tighten your cable tension. You can do this with the barrel adjuster that is built into either your shifter or derailleur. As you turn the barrel adjuster counter-clockwise, it screws the adjuster out taking up slack in the cable tension. This results in moving the derailleur a little further.
Pro Tip: A little bit can go a long way! Start with ¼ turns only and try the shifting again. Keep trying ¼ turns until you have it just right.
There are a few screws on the derailleur that will be tempting to adjust. Don’t! These are already adjusted to their positions to stop the derailleur from shifting the chain into the spokes and into the frame on the two most extreme gears. They only provide stopping points for the derailleur, they do not adjust the derailleur.
One thing to note. If you just can’t seem to get the shifting right, there is the possibility that the part of the frame that the rear derailleur is mounted to could be bent. This is called the derailleur hanger. Telltale signs are scrapes on your derailleur or if your bike tipped over onto its drive train side. Some are replaceable and some are not. If this is bent, there is nothing you can do to the cable tension that will help your adjustment. Go to your local bike store to get a professional opinion on your options. If you do have a replaceable hanger, it is good to get a couple as spares. Keep one in your seat bag just in case you need to do an on-the-road repair.