How to Adjust Gears on a Mountain Bike

A brief overview of how to adjust mountain bike gears...

Difficulty: Moderate

Instructions

Things You'll Need:

• slothead screwdriver
• pliers

1. When you change gears on your mountain bike you move a lever and a cable that moves what it called your derailers. Derailers move your bike chain over the correct gear. If your derailer is not adjusted correctly, it causes one of three things: over shifting; when your chain shifts off of the chain ring, under shifting; when your chain won't shift to the next gear and automatic shifting; when your bike moves to gears when you haven't even touched the lever.

2. 

   Place your bike on a bike stand. If you don't have a bike stand, hang your bike from it's handlebars and seat.

3. 
   Thumbshifter

   FIXING THE REAR DERAILER: Pull the right hand thumbshifter all the way back towards you and crank your pedal forward. The chain should be on the smallest cog in the rear of your bike. (A cog is the circular saw blade looking thing on your bike). If you are experiencing over shifting when riding, you will need to put your chain back on the smallest cog, than turn the "H", or high gear screw clockwise with a slothead screwdriver until you meet a slight amount of resistance. If your bike is undershifting, you will need to loosen and turn the "H" screw in a counterclockwise position until the chain is engaging on your cog.

4. 

   Next check your cable tension on the rear derailer. Loosen the bolt that holds the cable on the rear derailer. Grasp the end of the cable with pliers and gently pull the extra cable. Retighten the bolt.

5. To check the low gear on your rear derailer, this time pushing the thumbshifter away from you while cranking the pedal. If your chain shifts between your cog and the bicycle spokes, pull the lever back until the chain sits on the largest cog. Using your slothead screwdriver, turn the "L" or low screw clockwise until you feel resistance. Your rear derailer should be fixed. To check, move your bicycle pedal forward and moving your shift level forward and back to check each gear. If you experience any hesitations, make the appropriate adjustments.

6. FIXING THE FRONT DERAILER: Pull your left hand thumbshifter all the way towards you while cranking your bicycle pedal forward. Look to see if the chain is sitting on the smallest chain ring. If it is not, use your slothead screw driver to turn the "L" or low screw counterclockwise slowly. Keep cranking your pedal forward as you do this. Your chain should fall onto the small chain ring. When it does, stop turning the screw.

7. Next thing is to loosen the slack on your cable. Loosen the cable binder bolt, than use a pair of pliers to tighten the cable until it is snug. Retighten the bolt.

8. To set the high gear, push the left hand thumbshifter away from you while cranking the pedal. If the chain falls off the large chain ring, place it back on the large chain ring and pull your thumbshifter back so the front derailer is centered over the chain. Turn the "H" or high gear screw with your screwdriver until you meet resistance. When you have done this, move through all of your front gears to make sure the derailer is working properly.

Tips & Warnings

• If you have an indexed shifting system, you may need to have your local bike shop show you how to adjust your gears, or use the switch on your right hand thumbshifter to switch to a standard friction system. This allows you to change to the standard friction system to make adjustments if you are out on the road.

Resources

• Step by Step Video Showing How to Fix Your Bike Gears
• How to Adjust Your Mountain Bike Gears

[tikrit01]

on 11/3/2008 Awesome information! 5ss Thanks

[billm557]

on 10/22/2008 Good article. Check out my article on how to store bikes for the winter.