Rear Derailleur Maintenance

Things You'll Need

• You will need the following items for performing maintenance:
  * An old toothbrush will come in handy--the stiffer the bristles, the better.
  * Degreaser formula--either a spray can or a container will work.
  * Can of spray lube for the moving parts. Although there are many different types out there, a Teflon-based spray lube will work the best.
  * Old rag to wipe off the derailleur with
  * Small screwdriver in case you need to make minor derailleur adjustments

Cleaning and Oiling

• Regular monthly derailleur maintenance will comprise cleaning and oiling. This is the best way to keep a derailleur in tip-top condition. Flip the bike upside down before doing this, so you can turn the pedals and shift gears later on.

  Use your toothbrush to literally scrub off any dirt, grime or debris from all parts of the derailleur. You'll want to either dip it in a degreaser solution or spray some on the actual derailleur. The gear cogs should also be brushed, since dirt is picked up from them and transferred, via the chain, directly onto the springs and pulley wheels of the rear derailleur.

  Scrub the pulley wheels and the springs as well. Don't be shy about this; give them a good strong brushing.

  After brushing, liberally spray-lube the derailleur with oil to further remove dirt and gunk that has built up. Use an old rag to wipe off the excess oil, and with it all the old dirt.

  Now manually turn the pedals and shift the gears, spraying oil onto the mechanism and allowing it to work itself in. Wipe away all excess oil when finished.

Adjustments

• As a general rule, the derailleur itself will keep shifting correctly, but the chain will stretch, throwing the derailleur out of tune. When that happens, you'll need to make minor adjustments to get the chain and derailleur shifting properly again through the entire gear set on the rear wheel.

  The outer limit or "H" screw is the upper screw in this picture. When the shifting cable is loose, the chain should be perfectly aligned with the smallest gear cog on the bike. If it isn't, turn this screw in or out until the cog and the chain are in perfect alignment and in full contact with each other.

  The inner limit screw is the lower one, and it will align your chain and derailleur with the upper or largest cog on your gear set. Push your gear shift lever to the highest point, and there it should move the derailleur so that your chain is fully aligned with the largest gear.

  If there is slippage or the chain is not fully aligned, turn the lower screw until the chain and cog are completely in tune with each other, with no slippage and full contact between chain and gear.