How to Tune a Front Derailleur for a 2-Speed

Place your bike in an upright position against a sturdy wall or bench. If you have a bike stand, place the bike in the stand so the front derailleur is at waist height. If you're using a workbench, wall or stairs to lean your bike against, make sure the bike is stable before you begin. Make adjustments to the support until the bike is stable.

Place your hand on your left shift lever. The shift lever is the mechanism on your handlebar that allows you to move your chain up or down on the front chain rings, also called sprockets. Move the lever back and forth while looking straight down at your front derailleur. Make note of how much it moves past the smallest chain ring, and if it moves past the largest chain ring on the outside.

Look down at the derailleur to find the two limit screws. The limit screws are the two screws facing you and allow for adjustment. You can use either a flat or Phillips head screwdriver to make adjustments. According to Bicycletutor.com, if you have an older bike, the limit screw closest to the frame is for the inner front chain ring; newer bikes have these positions reversed. Test by inserting the screwdriver and turning the screw in both directions to see which direction the derailleur moves. The other limit screw is for adjusting the outer chain ring.

Turn your pedals and move the right shift lever until your chain is in the largest chain ring in back. Do the same with the left shifter, except put the chain on the smaller chain ring in front, as suggested by Bicycletutor.com. You need to maximize the tension on the chain to assure you are tuning the full range of your chain.

Adjust the derailleur by slowly turning the limit screw so it hides the chain ring when viewed from above. That is the inner limit you want. This prevents the chain from slipping or being over-shifted off the inside chain ring. Check by turning the pedals and move the left shifter to see the chain in action, if it falls off, there is too much space. Adjust the limit screw until the pedals rotate with the chain in place on the small ring, no noise can be heard and it does not fall off.

Move the left shifter until the chain is on the largest ring in the front, and move the right shift lever to move the chain to the smallest ring in back. Line up the front outer ring's limit by turning the left shifter and rotating the pedals at the same time to see if the chain slips off the outer ring or can not move the chain up to the outer chain ring. Adjust the limit screw so when looking straight down the inside guide of the derailleur, the inside guide lines up within 2 mm of the inside of the outer chain ring.

Using the right or left shifter, and simultaneously turning the bicycle crank forward, move the chain to the innermost position on both the front and rear derailleur. At this step you will begin to adjust the cable tension to insure the derailleur shifts smoothly between chain rings.

Move the front shift lever to the position corresponding to the outer chain ring while turning the crank forward. The chain should move to the outer chain ring smoothly. If the chain does not shift all the way to the outer chain ring, your cable tension is too loose.

Adjust the cable tension by rotating the cable tension adjustment screw one half turn outward. The adjustment screw is located at the point where the cable enters the shift lever and can be adjusted by hand.

Check if the tension is correct by first moving the shift lever so that the chain moves back to the inner chain ring. Move the shift lever so that the chain moves back to the outer chain ring. If the chain does not shift all the way to the outer chain ring, your cable tension is too loose. Adjust the cable tension by rotating the cable tension adjustment screw one-half turn outward. Repeat this step until the chain shifts smoothly from the inner chain ring to the outer chain ring.