Shimano RD-7800 - User Manual

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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 B-

tension 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.

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.

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.

Technical Service Instructions SI-5V50D

Rear Derailleur

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 which is not suitable for the

type of chain is used, sufficient connection force may not be

obtained, which could cause the chain to break or fall off.

• The end of the outer casing which has the aluminum 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.

• If it is necessary to adjust the

length of the chain due to a

change in the number of sprocket

teeth, make the cut at 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 prior to 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.

• Use 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.

Chain toolChain

10-speed super narrow

chain such as

CN-7801 / 6600

Reinforced

connecting pin

TL-CN32 / TL-CN23

with groove (3)

1 2

Link Pin

Reinforced

Connecting Pin

Aluminum cap

Dropout tab

5 mm Allen key

B-tension adjustment screw

Smallest

sprocket

Largest

chainring

Chain

90°

Guide pulley

Tension pulley

Right angle to the ground

Derailleur side

4-mm cap

Plastic cap or 4-mm cap

Guide pulley

Outer line of

smallest sprocket

Top adjustment

screw

Link Pin

1 2

Largest sprocket

Guide pulley

Largest sprocket Smallest sprocket

Low adjustment

screw

B-tension

adjustment screw

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.

Pull

Series

Type

Total capacity

Largest sprocket

Smallest sprocket

Front chainwheel

tooth difference

Double

Triple

Shifting lever

Gears

Outer casing

Rear derailleur

Type

Freehub

Cassette sprocket

Chain

Bottom bracket cable guide

DURA-ACE

ST-7801

ST-7803

SIS-SP41

RD-7800

SS / GS

FH-7800

CS-7800

CN-7801

SM-SP17

37 teeth or less

27T

11T

22 teeth or less

29 teeth or less

27T

11T

14 teeth or less

In order to realize the best performance, we recommend

that the following combination be used.

Specifications

Installation of the rear derailleur

Chain length

Stroke adjustment and cable securing

Bracket spindle

tightening torque:

8 - 10 N·m

{70 - 86 in. lbs.}

When installing, be careful that deformation is not caused by the

B-tension adjustment screw

coming into contact with

the dropout tab.

● In case of a triple

front chainwheel

RD-7800

Tightening torque:

5 - 7 N·m {44 - 60 in. lbs.}

Note:

Be sure that the

cable is securely in

the groove.

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.

Add 2 links (with the chain on

both the largest sprocket and

the largest chainring)

Largest

sprocket

Largest

chainring

Chain

+2 links

Lever (A)

When shifting to 3rd

Tighten the outer cable

adjusting barrel until the

chain returns to the 2nd

sprocket. (clockwise)

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 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.

These service instructions are

printed on recycled paper.

Loosen the outer casing

adjustment barrel until

the chain touches the

3rd sprocket and makes

noise. (counter

clockwise)

When no sound at all

is heard

Outer casing

adjustment barrel

Outer casing

adjustment barrel

Please note: specifications are subject to change for improvement without notice.

(English)

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

Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: +31-341-272222

3-77 Oimatsu-cho, Sakai, Osaka 590-8577, Japan

Not OK OK

Play

If the smallest sprocket is

15T or 16T

Need help?

Do you have a question about the Shimano RD-7800 and is the answer not in the manual?

Summary

General Safety Information

Safety Warnings

Use neutral detergent for cleaning. Avoid alkali/acid detergents. Use reinforced pins only for specific chain types.

Important Notes

Notes on gear shifting, derailleur maintenance, cable routing, and pulley tension.

Installation of Rear Derailleur

Stroke Adjustment and Cable Securing

Top Adjustment

Adjust the top adjustment screw so the guide pulley is below the smallest sprocket's outer line.

Connection and Securing of Cable

Connect cable to derailleur, take up slack, and secure in groove with specified torque.

Low Adjustment

Turn the low adjustment screw to align guide pulley with the largest sprocket.

B-Tension Adjustment

Adjust B-tension screw for guide pulley clearance to sprockets without touching.

Summary

General Safety Information

Safety Warnings

Use neutral detergent for cleaning. Avoid alkali/acid detergents. Use reinforced pins only for specific chain types.

Important Notes

Notes on gear shifting, derailleur maintenance, cable routing, and pulley tension.

Installation of Rear Derailleur

Stroke Adjustment and Cable Securing

Top Adjustment

Adjust the top adjustment screw so the guide pulley is below the smallest sprocket's outer line.

Connection and Securing of Cable

Connect cable to derailleur, take up slack, and secure in groove with specified torque.

Low Adjustment

Turn the low adjustment screw to align guide pulley with the largest sprocket.

B-Tension Adjustment

Adjust B-tension screw for guide pulley clearance to sprockets without touching.

The Shimano RD-7800 Rear Derailleur is a high-performance component designed for smooth and reliable gear shifting on bicycles. It is part of the DURA-ACE series, indicating its premium quality and intended use in competitive cycling or high-end road bikes.

Function Description:

The RD-7800 rear derailleur is responsible for moving the bicycle chain across the cassette sprockets, allowing the rider to select different gear ratios. It works in conjunction with a shifting lever, outer casing, and chain to provide precise and efficient gear changes. The derailleur's design incorporates SIS (Shimano Index System) shifting functionality, which ensures accurate and consistent shifts with a distinct click at each gear position. The B-tension adjustment screw allows for fine-tuning the guide pulley's proximity to the sprockets, optimizing shifting performance and preventing the pulley from touching the sprockets.

Important Technical Specifications:

Series: DURA-ACE
Model Number: RD-7800
Compatible Shifting Levers: ST-7801 (Double), ST-7803 (Triple)
Compatible Gears: 10-speed
Compatible Outer Casing: SIS-SP41
Compatible Freehub: FH-7800
Compatible Cassette Sprocket: CS-7800
Compatible Chain: CN-7801 (10-speed super narrow chain)
Compatible Bottom Bracket Cable Guide: SM-SP17

Type Specifications:

SS (Short Cage):
- Total capacity: 29 teeth or less
- Largest sprocket: 27T
- Smallest sprocket: 11T
- Front chainwheel tooth difference: 14 teeth or less
GS (Medium Cage):
- Total capacity: 37 teeth or less
- Largest sprocket: 27T
- Smallest sprocket: 11T
- Front chainwheel tooth difference: 22 teeth or less

Installation Specifications:

Bracket spindle tightening torque: 8 - 10 N·m {70 - 86 in. lbs.}
Cable securing tightening torque: 5 - 7 N·m {44 - 60 in. lbs.}

Usage Features:

Reinforced Connecting Pin: For connecting the narrow type of chain (CN-7801/6600), only the reinforced connecting pin with a groove (3) should be used. Using other pins or unsuitable tools may lead to insufficient connection force, potentially causing the chain to break or fall off.
Chain Length Adjustment: When adjusting chain length due to a change in sprocket teeth, cuts should be made at a place other than where the chain was previously joined with a reinforced connecting pin to prevent damage. After joining, ensure the connecting pin protrudes uniformly from both ends of the link surfaces.
B-Tension Adjustment: This screw allows for precise adjustment of the guide pulley's position relative to the largest sprocket. To use, mount the chain on the smallest chainring and largest sprocket, turn the crank arm backward, and adjust the screw until the guide pulley is as close as possible to the sprocket without touching. Repeat this process with the chain on the smallest sprocket to ensure no contact.
Top Adjustment (H-screw): This screw adjusts the guide pulley's position relative to the smallest sprocket. It should be adjusted so the guide pulley is directly below the outer line of the smallest sprocket when viewed from the rear.
Low Adjustment (L-screw): This screw adjusts the guide pulley's position relative to the largest sprocket. It should be adjusted so the guide pulley is directly in line with the largest sprocket.
Cable Connection: The cable should be securely connected to the derailleur and seated properly in its groove. After initial slack is taken up, re-secure the cable with the specified torque.
SIS Adjustment: This fine-tuning process involves operating the shifting lever to move the chain to the 2nd sprocket. While pressing the lever just enough to take up play, turn the crank arm. If the chain shifts to the 3rd sprocket or makes noise, the outer casing adjustment barrel needs to be adjusted. Tighten the barrel (clockwise) if the chain doesn't return to the 2nd sprocket. Loosen the barrel (counter-clockwise) if the chain touches the 3rd sprocket and makes noise. The "best setting" is achieved when the shifting lever is operated just enough to take up the play, and the chain touches the 3rd sprocket and makes noise. After this, return the lever to its original 2nd sprocket position, turn the crank arm clockwise, and if the chain is still touching the 3rd sprocket and making noise, slightly tighten the outer casing adjustment barrel clockwise until the noise stops and the chain runs smoothly. Finally, operate the lever through all gears to ensure no noise occurs.
Outer Casing Orientation: The end of the outer casing with the aluminum cap should be at the derailleur side.

Maintenance Features:

Cleaning and Lubrication: To ensure smooth gear shifting, the derailleur and all its moving parts (mechanism and pulleys) should be periodically cleaned and lubricated.
Chain Inspection: Regularly check the chain tension and for any damage. A chain that is too weak or damaged should be replaced immediately to prevent serious injury.
Derailleur Replacement: If the amount of looseness in the links is so great that adjustment is no longer possible, the derailleur should be replaced.
Pulley Inspection: If abnormal noise occurs due to looseness in a pulley, the pulley should be replaced. The tension pulley has an arrow mark indicating the direction of rotation, with the arrow side being the front.
Cable and Casing Maintenance: Ensure the inner cable and the inside of the outer casing are greased before use to ensure proper sliding. Check if the cable is lubricated and if the outer casing is too long or too short if gear shifting adjustment cannot be carried out.
Derailleur Hanger Parallelism: If gear shifting adjustment cannot be carried out, check the degree of parallelism at the rear end of the bicycle.
Genuine Parts: Shimano strongly recommends using only genuine Shimano replacement parts for optimal performance and safety.
Professional Assistance: For any questions regarding installation, adjustment, maintenance, or operation, it is advised to contact a professional bicycle dealer.
Lubrication for SIS Performance: For the best SIS performance, all power-transmission parts should be periodically lubricated.
Avoid Internal Cable Routing: Using a frame with internal cable routing is strongly discouraged as it tends to impair SIS shifting function due to high cable resistance.
Neutral Detergent for Chain: Only use neutral detergent to clean the chain. Alkali-based or acid-based detergents, such as rust cleaners, can damage or cause failure of the chain.