How to Align Bicycle Gears

How to Align Bicycle Gears

On older bikes, shifting is usually done with a lever that allows you to run smoothly between the gears. This old system allowed you to fine-tune the position of derailleurs to ensure that the chain ran smoothly no matter what gear you were in. Most newer bikes include twist or click shifters, in which one notch equals one gear. It's much easier to shift gears this way—but it means your notches have to be adjusted properly to ensure that one click does, in fact, equal one change in gear. Whether your bike is new or old, if your chain is clicking or rattling while you ride, if shifting results in no change or slipping through multiple gears, or if the chain frequently pops off when you shift, it's time to align your gears. (Technically, this part of the bike is a cog, but as a unit, they're often called "gears.")

How to Align Bicycle Gears

TOOLS:

• Screwdriver

• Ruler

• Needle-nose pliers

• Rags

MATERIALS:

• Bike cable

• Chain lubricant

1 Set the derailleur range. To adjust your gears, you must set the window in which your derailleur works—if the derailleur allows the chain to move too high it may pop off the largest gear, too low and it might pop off the smallest. First locate the limit screws. On most bikes, the front limit screws will be very near the gears, attached to a near vertical post on the bike's frame. There should be two Phillips head screws side by side (sometimes they are labeled "L" and "H"). The inner screw (away from the gears) is likely the "low" limit screw—adjust it so the inner plate of the chain guide is about 4 millimeters past the inner edge of the smallest gear. Do the same with the other limit screw, which controls how high or to the outside the chain can travel, so that the inner plate of the chain guide is about 4 millimeters past the largest gear. Do the same with the limit screws in the back.

How to Align Bicycle Gears

2 If needed, adjust the gear cable. A derailleur cable runs from your shifter, through a plastic sleeve, to the derailleur. If your derailleur doesn't have enough range, you may need to adjust the cable. Most cables have an anchor bolt on one end that's bigger in diameter than the cable to keep it in place. Pull the end of the cable with pliers to add tension to the cable, or loosen the anchor bolt to give it more slack.

How to Align Bicycle Gears

3 Check the position of the limit screws and derailleur cages. With the chain running on the largest gear, the cage should be 2 millimeters outside the chain. Likewise, with the chain running on the smallest gear, the opposite cage should be 2 millimeters inside the chain. If you have gears in the front and back, check the limit screws in both locations.

How to Align Bicycle Gears

4 Check the cable tension. The indexing (the way a shifter scrolls through gears) of modern twist or click shifters may need to be fine-tuned. You can do this by adjusting the tension of the cable. Look under the shifter where the cable enters the plastic housing. There should be a twist nut, called a barrel adjuster. Turning this adjuster by hand will slightly change the length of the plastic housing and so the tension of the wire within. Set the chain on the smallest gear. Then, with the bike's back tire off the ground, run the pedals and shift exactly one click. If the chain doesn't shift accurately to the next larger gear, turn the barrel adjuster to fine-tune the tension. The cable should be straight, no slack, and you should be able to tension it with your fingers. Do this for all gears, both front and back if needed. Once your gears are properly adjusted, the moving chain shouldn't scrape against the gears. It may take minute turns of the barrel adjusters to get the chain running perfectly.

How to Align Bicycle Gears

5 Lubricate the chain. Once the gears are running smoothly, spray them with chain lubricant and wipe off any excess with a rag.

PREVENTING CHAIN RUB

Chain rub happens when your bicycle chain gets stuck between the inner ring and the chainstay. To prevent it, try these tips:

• Make sure the chain is lubricated.

• Ease up when shifting.

• Replace worn teeth as needed.

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