Shimano BL-M770, BL-M771, BR-M770 Service Instructions

General Safety Information

WARNING

Improper use of your bicycle's brake system may result in a loss
of control or an accident, which could lead to a severe injury.
Because each bicycle may handle differently, be sure to learn
the proper braking technique (including brake lever pressure
and bicycle control characteristics) for your bicycle.
Consult your bicycle dealer and the bicycle's owners manual,
and practice your riding and braking technique.

Brakes designed for use as rear brakes should not be used as
front brakes.

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.

Be careful not to allow any oil or grease to get onto the brake
shoes. If any oil or grease do get on the shoes, you should
replace the shoes, otherwise the brakes may not work correctly.

Check the brake cable for rust and fraying, and replace the
cable immediately if any such problems are found. If this is not
done, the brakes may not work correctly.

Always make sure that the front and rear brakes are working
correctly before you ride the bicycle.

The required braking distance will be longer during wet weather.
Reduce your speed and apply the brakes early and gently.

If the road surface is wet, the tires will skid more easily. If the
tires skid, you may fall off the bicycle. To avoid this, reduce your
speed and apply the brakes early and gently.

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

CAUTION

The power modulator is a device that makes it easier to control
braking by increasing the cable stroke at the brake lever within a
certain constant range of braking force.
If the effective operating range of the power modulator will be
exceeded, the lever stroke and the brake will operate as a normal
V-BRAKE brake (sensitive and powerful). In that case, the brakes
may operate more powerfully than intended and may cause the
wheel to lock up. Therefore it is essential that you fully understand
and test the performance of the power modulator before use.

The power modulator is not equipped with a function to
prevent the wheel from locking up.

Braking Performance Comparison

Braking force at wheel

– To avoid serious injuries:

– To avoid serious injuries:

w/o power
modulator

Effective

operating range of

the power modulator

w/ power modulator

Cable stroke at brake lever

(kg)

Shimano BR-M770 Safety Information

WARNING

The M770 brake system is equipped with an adjustment block
in the wire hooking unit of the BL-M770/ST-M770 brake levers
which allows the rider to change the relationship between the
brake input and output. If the adjustment block is removed, the
braking force will be dramatically increased, so that a high level
of braking performance can be achieved from only a small
amount of lever movement. Accordingly, normal braking
operation may cause a greater-than-expected amount of
braking force to be applied, which could make the bicycle fall
forward, causing serious injury to the rider. To avoid this, please
read the following instructions thoroughly before removing the
adjustment block.

After removing the adjustment block, make sure that
you are completely used to the new braking
characteristics before riding the bicycle, otherwise
the bicycle might fall forward if you have to apply the
brakes suddenly, such as when a vehicle appears.

Without adjustment block removed (standard

1)

specifications for shipment)

With adjustment block removed

2)

An ample degree of braking force can be obtained from a
small amount of brake lever input, to provide a high level of
brake performance. However, if the brakes are operated
suddenly, there is the danger that the bicycle may fall
forward.
After removing the adjustment block, first ride the bicycle at
a speed of less than 6 mph (10 km/h) while applying the
brakes repeatedly in order to get a feel for the difference in
braking characteristics before riding at higher speeds.
Beginners should be particularly careful.

Use the BR-M770 V-BRAKE brake with SERVO WAVE
ACTION and adjustable V-BRAKE brake-compatible levers
such as the BL-M770 / ST-M770 brake levers.
If using the BL-M771 (3-finger brake levers) brake levers, use
the SM-PM40 power modulator with the V-BRAKE brakes. If the
power modulator is not used, it may cause excessive braking
force to be applied when the brake lever is operated, which in
turn could result in dangerous accidents.

– To avoid serious injuries:

With adjustment block

No adjustment block

SI-8EM0A-001

Multi-Condition

Brake System

Technical Service Instructions

Multi-Condition Brake System

By providing superior wet weather braking performance
(control and modulation), braking performance will not vary in
a multitude of conditions when using this brake system.

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

Series

Brake lever

V-BRAKE brake

Brake cable

Installation of the brake lever

Use a 4 mm Allen key to install the brake lever.

Use a handlebar grip with
a maximum outer
diameter of 32 mm.

In the case of carbon
handlebars, it may be
necessary to lower the
tightening torque in order to
prevent damage to the
handlebar. Please consult the
bicycle or handlebar
manufacturer regarding
the appropriate level of
tightening torque for
carbon handlebars.

Installation of the V-BRAKE brake

Insert the stopper pin of the brake body into the center spring

1.

hole in the frame mounting boss, and then secure the brake
body to the frame with the link fixing bolt.

DEORE XT

BL-M770 /
ST-M770

BR-M770

Tightening torque:
6 – 8 N·m {52 – 69 in. lbs.}

with SM-PM40

Tightening torque:
5 – 7 N·m
{43 – 61 in. lbs.}

5 mm Allen key

BL-M771

BR-M770

4 mm Allen key

While holding the shoe against the rim, adjust the amount of

2.

shoe protrusion by changing over the washer B (thick or thin)
so that dimension A is kept at 32 mm or more.

32 mm or more

FORWARD

A

Washer B (thick)

FORWARD

R

Washer A

Shoe fixing link

While holding the shoe against the rim, tighten the shoe fixing

3.

nut.

Washer B (thin)

Washer

Washer A

5 mm Allen key

Tightening torque:
6 – 8 N·m {52 – 69 in. lbs.}

R

FORWARD

R

Shoe fixing nut

1 mm

Pass the inner cable through the inner cable lead, and after

4.

setting so that the total of the clearances between the left and
right shoes and the rim is 2 mm, tighten the cable fixing bolt.

Inner cable lead

5 mm Allen key

Tightening torque:
6 – 8 N·m {52 – 69 in. lbs.}

B C

Depress the brake lever about 10 times as far as the grip and

6.

check that everything is operating correctly and that the shoe
clearance is correct before using the brakes.

Depress about
10 times

Replacement of the cartridge shoe

Remove the shoe fixing pin, and then slide the shoe along the

1.

groove to remove it from the shoe holder.

Shoe fixing pin

Shoe

R

FORWARD

There are two different types of shoe and shoe holder to be

2.

used in the left and right positions respectively. Slide the new
shoes into the grooves on the shoe holders while taking note
of the correct directions and pin hole positions.

For the left

Same at front and rear

Shoe holder

Shoe Shoe

FORWARD

FORWARD

L

L

Shoe
insertion

Shoe fixing pin

Insertion of shoe fixing pin is very critical to keep shoe

3.

properly fixed in place.

direction

For the right

Same at front and rear

FrontFront

Shoe holder

FORWARD

FORWARD

R

R

Shoe fixing pin

NOTE:

The optimum efficiency of the Multi-Condition Brake System
can be realized by using the brakes and brake levers in the
recommended set.

If the brake shoes have worn down until the grooves are no
longer visible, they should be replaced.

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
maintenance, please contact the place of purchase.

Spring hole

Stopper pin

Link fixing bolt

=

+

2 mm

C

B

Adjust the balance with the spring tension adjustment screws.

5.

2

1

Spring tension
adjustment screw

Spring tension
adjustment screw

11 22

1 mm 1 mm

Please note: Specifications are subject to change for improvement without
notice. (English)

One Holland, Irvine, California 92618, U.S.A. Phone: [phone]

Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: [phone]

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

C

Apr. 2007 by Shimano Inc. PIT. IZM. Printed in Malaysia