How to Adjust Gears on a Mountain Bike

How to Adjust Gears on a Mountain Bike
Shifting problems are common during mountain biking. You may experience problems like undershifting (bike won't shift into gear), sluggish shifting or overshifting (bike skips a gear). If you experience some of these common problems, you will need to adjust your gears. While you don't need to adjust on the trail, you should adjust the gears before your next ride.
 

Instructions

Difficulty: Easy

Step 1
Get a bike stand or hang bike up on hooks for easiest repair.

Step 2 Front Derailleur

Step 1
Make sure your limits screws are adjusted properly. You'll need to set the high and low limits on your front derailleur. Look at the front derailleur. You'll see 2 small screws side-by-side, ideally labeled "H" for High limit and "L" for Low limit. No labels? The one closest to the frame should be the Low limit. If in doubt, shift to low (smallest) gear and try each screw. The one that moves the derailleur in relation to the low gear is the winner.
Step 2
Using the left shifter, shift down to the lowest (smallest) front gear. If you experience overshift, where the chain moves past the low gear onto the frame tighten (turn right) the "L" screw with a screwdriver. If you experience undershift, where the chain will not lower onto the lowest gear loosen (turn left) the small screw. Tighten or loosen a quarter turn at a time until the chain shifts properly onto gear.
Step 3
Shift to highest (largest) front gear and repeat procedure in Step 3 using the "H" screw.
Step 4
Make sure that shifting is smooth between gears. Use barrel adjuster on top of cable next to shifter to tighten cable by turning counter-clockwise or loosen turning clockwise. Tighten if you have problems upshifting (to higher gears) loosen if you have problems downshifting (to lower gears). You could also loosen Allen bolt that holds the cable onto the front derailleur, pull taught and retighten. The chain should shift quickly and smoothly to each gear.

Step 6 Rear Derailleur

Step 1
Check your limits. Like front derailleur, rear derailleur has 2 limit screws, hopefully marked "H" and "L." The High limit screw should be above the low limit, but again you may need to test.
Step 2
Shift to lowest (largest) rear gear and adjust L screw for overshift (tighten) and undershift (loosen). Again, turn a quarter turn at a time until chain shifts appropriately onto highest gear.
Step 3
Shift onto highest (smallest) rear gear and repeat adjustments for overshift/undershift as needed, using the "H" screw.
Step 4
Adjust the cable tension using either the barrel adjuster on the rear derailleur itself or on the right shifter (depends on bike) to ensure that chain shifts smoothly up and down all rear gears (tighten tension for problems shifting to larger gears, loosen for problems shifting to smaller gears). You could also adjust by loosening Allen bolt, pulling taught and retightening bolt.

Step 10

Step 1
Seek additional repair. If you're gears still don't shift smoothly after adjusting cable and high/low limits, you may have a larger problem such as faulty shifting cables that need to be replaced. Bring bike to shop for service or refer to a more detailed repair manual for additional troubleshooting.

Step 11

Step 1
Lube your chain for the most fluid shifting performance and hit the trail!
 

Article Written By Chris Weiss

Chris Weiss is a freelance writer and outdoor enthusiast living outside of Salt Lake City. He has been mountain biking and snowboarding for over 15 years. Chris has written for various travel and outdoors websites and publications, and hopes to convey his experiences and passion for the outdoors to other enthusiasts and readers.

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