Shimano RD-7800 Rear Derailleur User Manual

June 11, 2024
Shimano

Shimano RD-7800 Rear Derailleur User Manual

Shimano-RD-7800-Rear-Derailleur-PRODUCT

General Safety Information

WARNING

  • Use neutral detergent to clean the chain. Do not use alkali-based or acid-based detergent such as rust cleaners as it may result in damage and/or failure of the chain.
  • Use the reinforced connecting pin only for connecting the narrow type of chain.
  • If connecting pins other than reinforced connecting pins are used, or if a reinforced connecting pin or tool is not suitable for the type of chain used, sufficient connection force may not be obtained, which could cause the chain to break or fall off.Shimano-RD-7800-Rear-Derailleur-FIG- \(1\)
  • If it is necessary to adjust the length of the chain due to a change in the number of sprocket teeth, cut some other place than the place where the chain has been joined using a reinforced connecting pin.
  • The chain will be damaged if it is cut at a place where it has been joined with a reinforced connecting pin.
  • Be sure to check that the connecting pin protrudes uniformly from the link surfaces at both ends after the chain has been joined.
  • Check that the tension of the chain is correct and that the chain is not damaged. If the tension is too weak or the chain is damaged, the chain should be replaced. If this is not done, the chain may break and cause serious injury.
  • Obtain and read the service instructions carefully before installing the parts. Loose, worn, or damaged parts may cause injury to the rider. We strongly recommend only using genuine Shimano replacement parts.
  • Read these Technical Service Instructions carefully, and keep them in a safe place for later reference.

Note

  • If gear-shifting operations cannot be carried out smoothly, clean the derailleur and lubricate all moving parts.
  • If the amount of looseness in the links is so great that adjustment is not possible, you should replace the derailleur.
  • You should periodically clean the derailleur and lubricate all moving parts (mechanism and pulleys).
  • If gear shifting adjustment cannot be carried out, check the degree of parallelism at the rear end of the bicycle.
  • Also, check if the cable is lubricated and if the outer casing is too long or too short.
  • If you hear abnormal noise as a result of looseness in a pulley, you should replace the pulley.
  • For smooth operation, use the specified outer casing and the bottom bracket cable guide.
  • Grease the inner cable and the inside of the outer casing before use to ensure that they slide properly.
  • The use of a frame with internal cable routing is strongly discouraged as it has tendencies to impair the SIS shifting function due to its high cable resistance.
  • The tension pulley has a mark which indicates the direction of rotation. The side with the arrow is the front side.

Technical Service Instructions

  • The end of the outer casing which has the aluminium cap should be at the derailleur side.
  • Parts are not guaranteed against natural wear or deterioration resulting from normal use.
  • For maximum performance, we highly recommend Shimano lubricants and maintenance products.
  • For any questions regarding methods of installation, adjustment, maintenance or operation, please contact a professional bicycle dealer.Shimano-RD-7800-Rear-Derailleur-FIG- \(4\)

To realize the best performance, we recommend that the following combination be used.

Shimano-RD-7800-Rear-Derailleur-FIG- \(5\)

Specifications

Shimano-RD-7800-Rear-Derailleur-FIG- \(6\)

Installation of the rear derailleur
When installing, be careful that deformation is not caused by the B-tension adjustment screw coming into contact with the dropout tab.

Shimano-RD-7800-Rear-Derailleur-FIG- \(7\)

Chain length
If the smallest sprocket is 15T or 16T.Add 2 links (with the chain on both the largest sprocket and the largest chainring)

Shimano-RD-7800-Rear-Derailleur-FIG- \(8\)

Stroke adjustment and cable securing

  1. Top adjustment
    Turn the top adjustment screw to adjust so that the guide pulley is below the outer line of the smallest sprocket when looking from the rear.Shimano-
RD-7800-Rear-Derailleur-FIG- \(9\)

  2. Connection and securing of the cable
    Connect the cable to the rear derailleur and, after taking up the initial slack in the cable, re-secure to the rear derailleur as shown in the illustration.

    • Tightening torque: 5 – 7 N·m {44 – 60 in. lbs.}
      Note: Be sure that the cable is securely in the groove.
  3. Low adjustment
    Turn the low adjustment screw so that the guide pulley moves to a position directly in line with the largest sprocket.Shimano-RD-7800-Rear-Derailleur-
FIG- \(13\)

  4. How to use the B-tension adjustment screw
    Mount the chain on the smallest chainring and the largest sprocket, and turn the crank arm backward. Then turn the Btension adjustment screw to adjust the guide pulley as close to the sprocket as possible but not so close that it touches. Next, set the chain to the smallest sprocket and repeat the above to make sure that the pulley does not touch the sprocket.Shimano-RD-7800-Rear-
Derailleur-FIG- \(14\)

  5. SIS Adjustment
    Operate the shifting lever several times to move the chain to the 2nd sprocket. Then, while pressing the lever just enough to take up the play in the lever, turn the crank arm.Shimano-RD-7800-Rear-Derailleur-FIG-
\(15\)Shimano-RD-7800-Rear-Derailleur-FIG-
\(16\)

Best setting

The best setting is when the shifting lever is operated just enough to take up the play and the chain touches the 3rd sprocket and makes noise. Return the lever to its original position (the position where the lever is at the 2nd sprocket setting and it has been released) and then turn the crank arm clockwise. If the chain is touching the 3rd sprocket and making noise, turn the outer casing adjustment barrel clockwise slightly to tighten it until the noise stops and the chain runs smoothly. Operate the lever to change gears, and check that no noise occurs in any of the gear positions. For the best SIS performance, periodically lubricate all power transmission parts.

SHIMANO AMERICAN CORPORATION
One Holland, Irvine, California 92618, U.S.A. Phone: +1-949-951-5003

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