Disc Brake System

Disc Brake System
<SM-RT53 / 53M / 53L>
General Safety Information
203 / 180 mm rotors
< Front >
• Please use extra caution to keep your fingers away from the rotating
disc brake rotor during installing or servicing the wheel. The rotor is
sharp enough to inflict severe injury to your fingers if caught within the
openings of moving rotor.
• The 203 mm and 180 mm rotors provide a higher braking force than the 160 mm rotors.
Make sure that you have a complete feel for the braking characteristics before using the
• The calipers and rotor will become hot when the brakes are operated, so do not touch
them while riding or immediately after dismounting from the bicycle, otherwise you may
get burned. Check that the brake components have cooled down sufficiently before
attempting to adjust the brakes.
• 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.
• Always make sure that the front and rear brakes are working correctly before you ride
the bicycle.
• Be careful not to allow any oil or grease to get onto the rotor and brake pads, otherwise
the brakes may not work correctly.
• If any oil or grease do get on the pads, you should replace the pads.
If any oil or grease gets on the rotor, you should clean the rotor. If
this is not done, the brakes may not work correctly.
• Before riding the bicycle, check that the pad thicknesses are 0,5 mm
or more.
• If noise occurs when the brakes are operated, it may indicate that
the brake pads have worn down to their usage limit. After checking
Pad wear
that the brake system has cooled down sufficiently, check the brake
pad thicknesses.
Replace the brake pads if the pad wear indicators are visible.
• Vapor lock may occur if the brakes are applied continuously. To
relieve this condition, momentarily release the lever.
Vapor lock is a phenomenon in which the oil inside the brake system becomes
heated, which causes any water or air bubbles inside the brake system to expand.
This can then result in a sudden increase in the brake lever stroke.
• Use only genuine Shimano mineral oil. If other types of oil are used, it may cause
problems with brake operation, and cause the system to be unuseable.
• Be sure to use only oil from a freshly-opened container, and do not re-use oil which has
been drained from the bleed nipple. Old oil or already-used oil may contain water which
could cause vapor lock in the brake system.
• Be careful not to let water or air bubbles to get into the brake system, otherwise vapor
lock may occur. Be particularly careful when removing the cover of the reservoir tank.
• If cutting the brake hose in order to adjust the length of the hose, or when changing over
the brake hose from left to right or vice versa, be sure to bleed the air from the hose by
carrying out steps (5), (8) to (10) given in “Adding mineral oil and bleeding air” in the
Service Instructions.
• When turning the bicycle upside down or on its side the brake system may have some
air bubbles inside the reservoir tank which are still there when the reservoir tank cover is
replaced, or which accumulate in various parts of the brake system when it is used for
long periods. The M445 disc brake system is not designed to be turned upside down. If
the bicycle is turned upside down or on its side, the air bubbles inside the reservoir tank
may move in the direction of the calipers. If the bicycle is ridden in this condition, there is
the danger that the brakes may not operate and a serious accident could occur.
If the bicycle has been turned upside down or on its side, be sure to operate the brake
lever a few times to check that the brakes operate normally before riding the bicycle. If
the brakes do not operate normally, adjust them by the following procedure.
< If brake operation is sluggish when the lever is depressed >
Set the brake lever so that it is parallel to the ground, and then gently depress the
brake lever several times and wait for the bubbles to return to the reservoir tank. It
is recommended that you then remove the reservoir tank cover and fill the reservoir
tank with mineral oil until no bubbles remain.
If the brakes still operate sluggishly, bleed the air from the brake system.
(Refer to "Adding the mineral oil and bleeding air".)
• If fluid leaks occur, immediately stop using the brakes and carry out the appropriate
repairs. If you continue riding the bicycle while fluid is leaking, there is the danger that
the brakes may suddenly stop working.
• If the quick release lever is on the same side as the rotor, there is the danger that it may
interfere with the rotor, so check that it does not interfere.
• It is important to completely understand the operation of your bicycle's brake system.
Improper use of your bicycle's brake system may result in a loss of control or an
accident, which could lead to severe injury. Because each bicycle may handle
differently, be sure to learn the proper braking technique (including brake lever pressure
and bicycle control characteristics) and operation of your bicycle. This can be done by
consulting your professional bicycle dealer and the bicycle's owners manual, and by
practicing your riding and braking technique.
• The M445 disc brakes are designed for optimum performance when used in
combination with the BR-M445 (calipers), BL-M445 (brake lever), SM-RT53 /
RT51 (rotor) and Shimano pad unit (B01S).
• Shimano disc brake systems are not compatible with tandem bicycles.
Because tandem bicycles have a high overall weight, the load on the brake
system increases during brake operation. If hydraulic disc brakes are used
with tandem bicycles, the oil temperature will become too high and vapor locks or
ruptures in the brake hoses may occur, and this will cause the brakes to fail.
• Obtain and read the service instructions carefully prior to installing the parts. Loose,
worn or damaged parts may cause the bicycle to fall over and serious injury may occur
as a result. 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.
■ Handling the mineral oil
• Use safety glasses when handling, and avoid contact with eyes. Contact with eyes may
result in irritation. In the event of eye contact, flush with fresh water and seek medical
assistance immediately.
• Use gloves when handling. Contact with skin may cause a rash and discomfort.
In the event of skin contact, wash well with soap and water.
• Inhalation of oil mist or vapors may cause nausea. Cover nose and mouth with a
respirator type mask and use in a well ventilated area. If mist or vapor is inhaled, go
immediately to an area with fresh air. Cover up with a blanket. Stay warm and stable and
■ When cleaning with a compressor
• If disassembling the caliper body to clean the internal parts using a
compressor, note that moisture from the compressed air may remain on the
caliper components. Let the caliper components dry sufficiently before
reassembling the calipers.
• The SM-RT53L/M 203/180 mm rotors has a larger diameter and greater
curvature than the 160 mm cross-country rotors. As a result, it may touch the
brake pads.
• If the brake caliper mounting boss and the dropout are not parallel, the rotor
and caliper may touch.
• When the bicycle wheel has been removed, it is recommended that pad
spacers should be installed. The pad spacers will prevent the piston from
coming out if the brake lever is depressed while the wheel is removed.
• If the brake lever is depressed without the pad spacers installed, the pistons will
protrude further than is normal. Use a flat-tipped screwdriver or similar tool to
push back the brake pads, while being careful not to damage the surfaces of
the brake pads. (If the brake pads are not installed, push the pistons straight
back in, while being careful not to damage them.)
If it is difficult to push the brake or pistons back, remove the bleed screw and
install the oil funnel and then try again. You will need to carry out the bleeding
operation at this time too.
• Use isopropyl alcohol, soapy water or a dry cloth when carrying out cleaning
and maintenance of the brake system. Do not use commercially-available brake
cleansers or silencing agents, as they can cause damage to parts such as
• Do not remove the pistons when disassembling the calipers.
• If the rotor is worn, cracked or warped, it 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.
Rotor fixing lock ring
TL-LR15 / LR10
Bleed screw
Tightening torque:
40 - 50 N·m {350 - 435 in. lbs.}
<Wire ring method>
■ Installation of the brake lever (BL-M445)
Secure the brake lever as shown in the illustration. (Check that the brake lever does not interfere
with the shifting lever during operation. Refer to the Service Instructions for the shifting lever also.
Some types might require the shifting lever to be installed first, due to the position of the shifting
lever fixing bolts.)
Usage location
■ Installation of the hose
Refer to the Service Instructions for the SM-BH59 brake hose (SI-8H20) for details on installing
the hose.
Do not let the hose become twisted when installing. Make sure that the calipers and levers are in
the positions shown in the illustrations.
Rotor fixing lock ring
TL-LR15 or TL-LR10
Brake lever fixing bolt
Allen key 5 mm
Caliper fixing bolt / Adapter fixing bolts
Allen key 5 mm
Brake pad fixing shaft
Radio pliers
Brake hose fixing bolt
8 mm wrench
Oil funnel, Oil stopper
Phillips screwdriver #2
Bleed nipple
Socket wrench 7 mm
The M445 brake system is designed so that as the brake pads become worn,
the pistons gradually move outward to automatically adjust the clearance between
the rotor and the brake pads. Therefore, you need to push the pistons back to their
original positions when replacing the brake pads.
● International standard mounting type
< Front >
Adapter fixing
Check that the spokes have been laced as shown in the illustration.
A radial assembly cannot be used.
Lace the spokes as shown in Figure 1 below for the left side of the front wheel
(the side where the roter is installed), and the left and right sides of the rear
wheel, and as shown in Figure 2 below for the right side of the front wheel.
Front left
Disc Brake System
Rear left Rear right
Brake Lever
Cable Supporter
Mineral Oil
SM-RT53 (160mm)
SM-RT53M (180mm)
SM-RT53L (203mm)
Brake pad unit
Provisionally install the caliper to the
frame (so that the caliper can move
sideways), depress the brake lever so that
the rotor is being clamped by the pads,
and then tighten the caliper fixing bolts.
B01S (Resin pads)
and remove the brake pads as shown
in the illustration.
Brake pads
2. Clean the pistons and surrounding area.
3. Push the piston back in as far as it will
go, while being careful not to twist it.
< Front >
4. Install the new brake pads, and
then install the pad spacers.
Caliper fixing
< Rear >
Fig. 1
■ Installation of the rotor
<SM-RT51 / 51M>
Caliper fixing
Fig. 2
Fig. 1
Tightening plate
Pad spacer
Adapter fixing
5. Depress the brake lever several times to check that the operation becomes stiff.
6. Remove the pad spacers, install the wheel, and then check that there is no interference
Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}
Install the rotor and the rotor tightening
plate to the hub, and then install and
tighten the bolts as shown in Fig. 1.
between the rotor and the caliper. If they are touching, adjust while referring to
"Installation of the caliper".
■ Adjustment when the pistons are not operating correctly
The caliper mechanism includes two pistons. If these pistons do not operate properly or if
they protrude unevenly, or if the brake pads remain in contact with the rotor, adjust the
pistons by the following procedure.
Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}
* TORX is a registered
1. Remove the wheel and the brake pads.
trademark of Camcar LLC.
While wearing gloves, apply a force to the rotor to
turn it in a clockwise direction as shown in Fig. 2.
While doing this, tighten the rotor fixing bolts in
the order shown in the illustration.
Clean the pistons and surrounding area.
Tightening torque:
2 - 4 N·m {18 - 35 in. lbs.}
Either a cap method or a wire ring method can be used to stop the bolts from turning.
Use whichever method is suitable for the front fork and frame.
Use a flat-tipped screwdriver or similar tool to bend the edges of the tightening
plate over the heads of the bolts as shown in Fig. 3.
Fig. 2
Fig. 3
< Front >
Post type
2. Push the piston back in straight, without bending it.
3. Install the brake pads and the pad spacers.
4. Depress the brake lever as far as it will go, and then operate it several more times so
160 mm rotor
In order to realize the best performance, we recommend that the following
combination be used.
1. Remove the wheel from the frame,
● Post mounting type
Front right
( For Cross-Country )
If oil adheres to the brake pads after oil is added, or if the brake pads are worn down to a
thickness of 0.5 mm, replace the brake pads.
For international-standard mounts, attach adapters to calipers for post-type mounts.
(Separate front and rear adapters are available.)
■ Wheel spoke lacing
direction of
Tightening torque:
0.3 - 0.5 N·m {2.7 - 4.4 in. lbs.}
■ Brake pad replacement
< For right lever >
caliper fixing bolts.
Cable supporter
It is recommended that you replace the oil inside the reservoir tank if it becomes
severely discolored. Use only genuine Shimano mineral oil.
Dispose of the waste oil according to proper country and/or state disposal
2. Depress the brake lever so that the rotor is being clamped by the pads, and then tighten the
Allen key 2 mm
< Usual type of cable stopper >
■ Mineral oil replacement period
Be sure to read the service instructions for the “Adding mineral oil
and bleeding air” in conjunction with these service instructions.
adapter to the frame.
Bleed screw
Bolt ➁
For C-shaped guides and the
usual type of cable stoppers,
use the special Shimano
cable supporter (sold
separately) to secure as
shown in the illustration.
1. Loosen the caliper fixing bolts so that the caliper can move sideways, and then install the
Bolt ➀
Operate the brake lever several times and check whether the brakes operate normally or
not. Also check that there are no oil leaks visible.
< For left lever >
■ Installation of the calipers (BR-M445) and securing the hose
If bolt ➀ tries to loosen (turn in the counterclockwise direction), force is
applied via the wire to turn bolt ➁ in the tightening direction (clockwise).
However, bolt ➁ cannot turn any further in the tightening direction.
Accordingly, this prevents bolt ➀ from turning in the loosening direction
because it is also connected via the wire. If either one of the bolts tries to
loosen, this causes a force to be applied to the other bolt to turn it in the
tightening direction. In other words, this system prevents the bolts from
< C-shaped guide >
Rotor fixing bolts
(#T25 torx)*
Technical Service Instructions
Oil funnel
The following tools are needed to assemble this product.
Oil stopper
Brake lever Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}
* An oil funnel and an oil stopper will be required when bleeding the
Post type
seek professional medical advice.
• Do not drink. May cause vomiting or diarrhea.
• Keep out of reach of children.
• Do not cut, heat, weld or pressurize the oil container, as this may cause
explosion or fire.
• Disposal of Used Oil : Follow local county and/or state codes for disposal. Use
care when preparing oil for disposal.
• Directions : Keep the container sealed to prevent foreign objects and moisture
from getting inside, and store it in a cool, dark area away from
direct sunlight or heat.
■ Burn-in period
• Disc brakes have a burn-in period, and the braking force will gradually increase
as the burn-in period progresses. Make sure that you are aware of any such
increases in braking force when using the brakes during the burn-in period. The
same thing will happen when the brake pads or rotor are replaced.
< Rear >
< Rear >
that the two pistons all move to their initial positions.
This service instruction explains how to use and maintain the Shimano bicycle
parts which have been used on your new bicycle.
For any questions regarding your bicycle or other matters which are not
related to Shimano parts, please contact the place of purchase or the bicycle
5. Remove the pad spacers, install the wheel, and then check that there is no interference
between the rotor and the caliper. If they are touching, adjust while referring to
"Installation of the caliper".
Tightening plate
One Holland, Irvine, California 92618, U.S.A. Phone: +1-949-951-5003
Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: +31-341-272222
If the oil level drops after the brake pads have been replaced or the piston has been
adjusted because it is not working correctly, the braking force may become weaker. If
this happens, install the oil funnel and carry out the bleeding operation to top up the oil.
3-77 Oimatsu-cho, Sakai-ku, Sakai-shi, Osaka 590-8577, Japan
* Service Instructions in further languages are available at :
Please note: specifications are subject to change for improvement without notice. (English)
© Oct. 2009 by Shimano Inc. XBC IZM Printed in Malaysia.
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