PROBLEM: Your bike’s been working great. But lately you notice that rear shifts to easier gears (bigger cogs) are becoming hesitant and noisy.
SOLUTION: Snug the derailleur cable. This fix is so easy that it doesn’t even require tools.
During shifts, the cable wears in and stretches. Slack develops. The derailleur no longer moves the chain cleanly onto the next cog.
Start by putting your bike in a rack, or at least elevate the rear wheel. Shift to the largest chainring and smallest cog.
Spin the crank and try a shift to the next cog. Lots of clattering? Delayed shift or no shift at all? Click back to the smallest cog.
Look where the cable housing enters the rear of the derailleur. You’ll see a knurled “barrel” that you can turn with your fingers. Rotate this barrel half a turn counterclockwise. This removes a bit of cable slack.
Try the shift again. Better, but still not like new? Give the barrel another half turn. Shift again and, if necessary, turn again. Keep it up in half-turn increments till the shift is silky.
As usual, there can be too much of a good thing. If you take up too much cable, the chain might contact the next larger cog after the shift is completed. You’ll hear rattling, and if you look from behind you’ll see the chain touching. Correct this by turning the barrel clockwise.
Once that first shift is golden, try all the others from each chainring. If shifts still seem balky going to larger cogs, turn the barrel counterclockwise. If the chain hesitates when dropping to smaller cogs, turn the barrel clockwise.
After you have the knack, you can impress your riding buddies by hopping off at a stoplight to do a five-second tune up. You’ll know exactly which way to turn the barrel to sharpen the shifting.