Shimano FH-M801, FH-M806 Service Instructions

Check that the spokes have been laced as shown in the illustration.
A radial assembly cannot be used.

Rotating direction of wheel

1. Install the sprockets to the FH-M806 / FH-M801 freehub, place

the freehub onto the frame and pass the hub axle through it.

2. Install the hub axle fixing nut that is attached to the rear

derailleur onto the hub axle.
* FH-M806 (ø12mm), FH-M801 (ø10mm)

3. Turn the hub axle to secure the freehub and the rear derailleur to

the frame.
Check that the pawl on the fork end is set into the end stopper.

Installation to the frame

Wheel spoke lacing Installation of the rotor

Freewheel hub / Rear derailleur

tightening torque:

35 - 45 N·m {305 - 392 in.lbs}

6 mm Allen key

For vertical dropout
specifications

For BMX-style dropout
specifications

Frame

Cassette sprocket

Freehub

Hub axle

Rear derailleur

General Safety Information

• Off-road bicycle riding and extreme mountain bike riding, represented in part by

North Shore style riding, “trials riding”, or urban stunt riding is an inherently
dangerous activity. There is a risk of being involved in an accident that can result
in a serious injury or even death. It is strongly recommended that riders wear
protective head and body gear and perform thorough safety checks of their
bicycles before riding. Please remember that you are riding at your own risk and
that you have to consider your experience and your skills very carefully.

• The FH-M806 / FH-M801 freehub are designed for off-road bicycle riding and extreme
mountain bike riding, that are represented in part by North Shore style riding, “trials riding”, or
urban stunt riding. However, depending on the riding condition, The hub axle could develop a
crack, which may result in failure of the hub axle. This can lead to an accident that could
result in serious injury or even death.
Before riding, you should carefully check your hubs to make sure that there are no cracks in
the axles , and if you find any sign of a crack or any other unusual condition, do NOT use the
bicycle.

• A hub axle is an essential component for the firm and reliable attachment of a rear hub and a
rear derailleur to the bicycle frame. Its material, strength, size and shape all are key to
accomplishing this goal. That is why Shimano ships a hub axle with a hub.
We strongly recommend that you use the hub axle that is shipped with a hub when attaching
the hub to the bicycle frame. A wheel may come off and cause a serious injury to the rider if
you use a different hub axle because (1) a different hub axle may not be long enough to be
able to sufficiently tighten the rear hub, and/or (2) a different hub axle may break due to lack
of strength.
Shimano does not sell its hub axle separately except when a customer uses Shimano’s RD­M806 / M805 or RD-M801 / M800 rear derailleur with a non-Shimano rear hub. However, if a
customer chooses to use a non-Shimano rear hub, the customer is doing so at his/her own
risk and is responsible for making sure that the wheel is firmly fixed.

• Before riding, confirm that the hub axle has been tightened with torque of 35 - 45 N·m and the
wheel has been secured to the frame. Serious injury can result from falling if the wheel comes
off.

• 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

• When installing the wheel and rear derailleur onto the frame, first apply grease to the hub axle
by following directions in the Service Instructions.

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

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

• 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.

• This product is not warranted against damage resulting from use such as jumping while riding
or if the bicycle falls over, except if such malfunctions result from non conforming materials or
manufacturing methods.

• Parts are not guaranteed against natural wear or deterioration resulting from normal use.

• For maximum performance we highly recommend Shimano lubricants and maintenance
products.

WARNING

Technical Service Instructions SI-3C40A

FH-M806
FH-M801

Freehub

Specifications

Series

Shifting lever

Outer casing

Rear derailleur

Type

Freehub

Gears

Cassette sprocket

Chain

Bottom bracket guide

SAINT

ST-M800 / SL-M800

SIS-SP41

RD-M806 / M805 RD-M801 / M800

SGS / GS / SS

FH-M806 FH-M801

Front hub

HB-M801

9

CS-M970

CN-HG93

SM-SP17 / SM-BT17

In order to realize the best performance, we recommend that the following
combination be used.

Model No.

Gears

FH-M806

9

36 / 32

150 mm

12 mm

RD-M806 / RD-M805

135 mm

10 mm

RD-M801 / RD-M800

FH-M801

9

36 / 32No. of spoke holes

Overlock nut dimensions

Axle diameter

Applicable rear derailleur

Freehub

End stopper

Tightening torque:

40 N·m {350 in. lbs.}

Rotor
installation ring

TL-LR20

Rear left Rear right

Maintenance

These units can be disassembled as shown in the illustrations. Grease should be applied to each part at periodic
intervals.

1

2

3

1

2

3

DURA-ACE grease

(Y-04110000)

Freewheel body fixing nut (M15)

Left hand cone (M20)

Left hand lock nut (M20) TL-HS22 (24mm)

TL-HS21 (23mm)

TL-HS22 (17mm)

Right hand thread

Right hand thread

Left hand thread

Part name Thread type Special tool Tightening torque

Applying grease
(Special freehub grease)

Special grease is used for the
freewheel body. Do not mix it with
other types of grease, as this may
cause problems with the operation of
the freewheel clutch mechanism.
(Grease part number: Y-3B980000)

3
2
T

ba

ba

2
8T

ba

24T

ba

21T

ap ba

1
8T

1
1T

a

Q

a

r

ba

1

2

T

a

Q

ar

ba

9S

C

S

-

6

J

P

A

A

N

M

9

0

H

P

Y

E

E

R

G

L

I

D

11

T

ap

a

Q

ba

a

r

16
T

ap

a

Q

ar

ba

1
4T

ap

as

34T

ap

as

30T

ap

as

26T

ap

as

23T

as

2
0
T

as

1
7
T

as

au

11T

as

au

1
3
T

as

au

15
T

C

S

-

6

J

P

A

A

N

M

9

0

H

P

Y

E

E

R

G

L

I

D

11

T

Installation of the sprockets

For each sprocket, the
surface that has the group
mark should face outward
and be positioned so that
the wider part of each
sprocket and the A part
(where the groove width is
wide) of the freewheel
body are aligned.

(aQ)

(as)

For installation of the HG sprockets,
use the special tool (TL-LR15) to
tighten the lock ring.

To replace the HG sprockets, use the
special tool (TL-LR15) and TL-SR21 to
remove the lock ring.

The groove is
wide at one
place only.

a

c

-

1

4

T

A

Wide part

Tightening torque:

30 - 50 N·m {261 - 434 in. lbs.}

Sprocket spacer

Lock ring spacer

Lock ring spacer

Lock ring

Lock ring

One Holland, Irvine, California 92618, U.S.A. Phone: [phone] Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: [phone] Oimatsu-cho Sakai-ku, Sakai, Osaka 590-8577, Japan

These service instructions are printed on recycled paper.
Please note: specifications are subject to change for improvement without notice.(English) © Aug. 2006 by Shimano Inc. XBC SZK Printed in Japan.

30 - 35 N m

{261 - 305 in. lbs.}

20 - 25 N m

{175 - 218 in. lbs.}

Applying grease

Applying grease

Applying grease

DURA-ACE grease

(Y-04110000)

Applying grease

DURA-ACE grease

(Y-04110000)

Applying grease

Hub axle fixing nut

M801 (ø10mm)
M806 (ø12mm)

FH-M801

FH-M806

ø10mm

Axle diameter Vertical dropout

BMX-style

dropout

ø12mm

✕

✕

✕

—

Check that the axle on the right hand side protrudes about
20 – 30 mm. If it is not long enough, the wheel may come off
because the hub axle does not tighten the hub sufficiently.

Lock ring

Tool
(TL-SR21)

Disassembly

TL-LR15

Seal

(Lip is on the outside)

Outer seal ring

Ratchet body

Rotor mount cover

Seal

(Lip is on the outside)

Seal

(Lip is on the outside)

Note:

• When removing and installing the seal, do it very carefully so that the seal does not become bent.
When reinstalling the seal, make sure that it is facing the right way, and insert it as far as it will go.

• Do not disassemble the dust-proof cover which is crimped onto the cone.

• The rotor fixing serrations may become damaged if the disc brake rotor has not been installed to the FH-M806 / M801,

so install the accessory rotor mount cover.

• Do not remove the outer seal ring except when replacing the ratchet body.

• Do not attempt to disassemble the freewheel body, because it may result in a malfunction.