How to Adjust Shimano Gears

How to Adjust Shimano Gears
The variable-ratio transmission known as a "derailleur" allows a bicyclist to tackle both hills and flats with equal efficiency. This convenience is possible thanks to your bike's rear and front derailleurs, which move the chain from one sprocket ratio to another. The majority of derailleur systems in use today are either manufactured by Shimano, or are Shimano-compatible. Adjusting your Shimano bike gears is mainly a matter of ensuring that these derailleurs are set properly. If your bike isn't shifting cleanly, take the time to make the following adjustments.

Instructions

Difficulty: Moderate

Rear derailleur

Things You’ll Need:
  • Phillips #2 screwdriver
Step 1
Shift your chain to the smallest rear cog. From behind the bike, eye the alignment between the derailleur pulleys and the smallest cog. Are they in line?
Step 2
To move the pulleys to the left, turn the high range screw at the rear of the derailleur to the right. The screw will be the lower of two screws, marked with an "H." To move the pulleys to the right, turn the screw to the left.
Step 3
Shift from the smallest cog into the next gear. Does the chain shift cleanly, or does it stall? If the chain is stalling, turn the barrel adjuster at the back of the derailleur a fraction to the left. Continue turning until the chain moves crisply onto the next cog.
Step 4
Check your low range adjustment now. Shift all the way to the largest cog. If the chain stalls before the largest cog, turn the low range screw to the left. The screw will be marked with an "L." If the chain overshoots the largest cog, turn the screw to the right.

Front derailleur

Step 1
Shift your chain into the smallest front chainring. Sight the gap between the chainring and the inner plate of the derailleur. The gap should be no more or less than 2 mm.
Step 2
To lessen the gap, turn the low range screw at the top of the derailleur to the right. This will be inside screw, likely marked with an "L." To widen the gap, turn the screw to the left.
Step 3
Shift to the largest chainring. If the chain stalls, turn the barrel adjuster on the front derailleur cable to the right until the chain carries over.
Step 4
With the chain on the largest chainright, sight the gap between the derailleur plate and the chainring. Once again, the gap should be 2 mm. To reduce the gap, turn the high range screw to the right. To increase the gap, turn the screw to the left.
Step 5
Shift the chain into the small chainring and then shift it back. Re-check the gaps and make further adjustments if necessary.

Tips & Warnings

 
New derailleur cables will continue to stretch for a time. Derailleurs will need to be adjusted with some frequency, until the cable "settles."
 
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Article Written By Matthew Ferguson

Matthew Ferguson is a writer living in Savannah, Ga. He has been writing for over 10 years and his work has appeared on various online publications. A collection of his short stories was published in spring 2010. He is a graduate of Appalachian State University.

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