Shimano SG-8R20, SG-8R25, CJ-8S20 Service Instructions Manual

General Safety Information

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SI-34R0B

WARNING

When securing the brake arm to the frame, be sure to
securely tighten the clip screw and clip nut to the
specified tightening torque. Use lock nuts with nylon
inserts (self-locking nuts) for the clip nut. It is
recommended that standard Shimano parts be used for
the clip screw, clip nut and brake arm clip. If the clip nut
comes off the brake arm, or if the clip screw or brake arm
clip becomes damaged, the brake arm may rotate on the
chainstay and cause the handlebars to jerk suddenly, or
the bicycle wheel may lock and the bicycle may fall over,
causing serious injury.

When installing the hub to the frame, be sure to install
the correct non-turn washers to the left and right sides,
and securely tighten the hub nuts to the specified
torques. If the non-turn washers are installed to one side
only, or if the hub nuts are not tightened sufficiently, the
non-turn washer may fall out, which could cause the hub
axle to rotate and the cassette joint to turn. This may
then cause the handlebars to be accidentally pulled by
the shifting cable, and an extremely serious accident
could result.

Obtain and read the service instructions carefully prior to
installing the parts. Loose, worn, or damaged parts may
cause serious injury to the rider.
We strongly recommend only using genuine Shimano
replacement parts.

Check that the wheels are fastened securely before
riding the bicycle. If the wheels are loose in any way,
they may come off the bicycle and serious injury may
result.

Read these Technical Service Instructions carefully, and
keep them in a safe place for later reference.

– To avoid serious injuries:

SG-8R20

Inter-8 Hub

SG-8R25
CJ-8S20

Technical Service Instructions

Be sure to read these service instructions in conjunction
with the service instructions for the Inter-M Brake and the
Inter-8 shifting lever before use.

Installation of the cassette joint to
the hub

Install the driver cap to the driver on the right side of the

1.

hub body.

Driver cap

Driver

Cassette joint

Note the
direction

NOTE:

You can shift gears while pedaling, but on rare occasions
the pawls and ratchet inside the hub may produce some
noise afterwards as part of normal gear shifting operation.

The CJ-8S20 cassette joint should only be used with
sprockets from 16T to 23T.

If the wheel becomes stiff and difficult to turn, you should
lubricate it with grease.

Do not apply any grease to the inside of the hub,
otherwise the grease will come out again.

You should periodically wash the sprockets in a neutral
detergent and then lubricate them again. In addition,
cleaning the chain with neutral detergent and lubricating it
can be a effective way of extending the useful life of the
sprockets and the chain.

If the chain keeps coming off the sprockets during use,
replace the sprockets and the chain.

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 handling or
adjustment, please contact the place of purchase.

Driver cap

Turn the cassette joint pulley in the direction of the

2.

arrow in the illustration to align the red marks on the
pulley and the bracket. With the cassette joint in this
condition, install it so that the red mark on the
cassette joint is aligned with the red mark on the right
side of the hub body.

Should be aligned

Pulley

Bracket

CJ-8S20

JAPAN

Cassette joint

CJ-8S20

JAPAN

Align the red
marks to install.

Align the red
marks to install.

Right side of
the hub body

Installation of the hub to the frame

Mount the chain on the sprocket, and then set the hub

1.

axle into the fork ends.

Hub axle

JAPAN

CJ-8S20

LOCK

Place the non-turn washers onto the right side and left

2.

side of the hub axle. At this time, turn the cassette joint
so that the projecting parts of the non-turn washers fit
into the grooves of the fork ends. If this is done, the
cassette joint can be installed so that it is almost parallel
to the chainstay.

Non-turn washer (for left side)

JAPAN

CJ-8S20

Chainstay

Fork end

Cassette joint

Groove of fork end

LOCK

Non-turn
washer
(for right side)

7R

Secure the cassette joint to the hub with the cassette

3.

joint fixing ring. When installing the cassette joint fixing
ring, align the yellow mark with the yellow mark on
the cassette joint pulley, and then turn the cassette joint
fixing ring 45° clockwise.

LOCK

Align the

Cassette joint
fixing ring

yellow marks
to install.

Cassette joint pulley

CJ-8S20

JAPAN

Turn 45°

LOCK

CJ-8S20

JAPAN

Cassette joint fixing ring

Fit the cassette joint
bracket securely.

Different types of left and right non-turn washers
are available for use with standard and reversed
fork ends. Use whichever non-turn washers are
suitable.

Non-turn washer

Fork end

Standard

Reversed

Reversed

(full chain case)

7R

Mark/Color

Right

5R / Yellow

Left

5L / Brown

7R / Black 7L / Gray

6R /Silver

5R / Yellow

Mark

6L / White

5L / Brown

Size

20

38

= 0

= 0

The projecting parts should be
on the fork end side.

Install the non-turn washers so that the
projecting parts is securely in the fork end
grooves on either side of the hub axle.