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Derailleur Adjustment

When it comes to routine bike maintenance, derailleur adjustment is often one of the most intimidating topics for cyclists. Fortunately, there are just a few key pieces of information to know to get your bike shifting like new again. There are many detailed articles on derailleur tuning on the internet. My goal here is only to provide a quick overview of the process.

I'll start with the rear derailleur. First, you want to shift to the lowest gear, so that the chain is closest to the spokes. Next, shift to a middle gear on the cassette. If you shifted four times, you should be in the 5th gear, which will be right in the middle of a nine speed cassette.  Most derailleurs have two quick adjust thumb screws, and you'll probably want to use the one attached to the derailleur at this point. If you shifted four times, and you can see that the chain is on the 5th gear, you're in good shape already and you only need to fine-tune your shifting. If the chain is on the 4th or 6th gear (or worse) you might need to do some more work, including adjusting the cable length. In this article, we'll assume that your cable has only stretched a little, and shifting isn't too far off. As you turn the thumb screw on the derailleur, you'll see that the derailleur moves slightly toward or away from the wheel, depending on which way it is turned. You'll want to turn this screw until the derailleur leads the chain directly over the center of the 5th gear. Once this is aligned, the shifter should pull or release just enough cable to drop the chain over the other gears. 

The second step of rear derailler tuning should not have to be done as often, since it is not affected by cable stretch. In this step you want to adjust the two small screws on the derailleur to prevent the chain from failing off of the cassette on the frame side, or worse, on the spoke side. If the chain does fall off the cassette on the spoke side, you could do serious damage to your wheel and possibly put an early end to your tour. First, you'll want to shift to your lowest gear again, putting the chain on the largest gear of the cassette. Just like with the thumb screw, you'll want to adjust the screw labeled "L" until the derailleur is leading the chain directly over the gear. Next, shift to your highest gear and repeat the process by adjusting the "H" screw until the chain is led directly over the smallest gear on the cassette. The "H", "L", and thumb screws are typically all you will need to adjust during your tour if you start with a properly tuned bike.