Hydraulic Road Disc (HRD) Brake Hose Shortening and Bleed Manual
Bleed Manuals

Hydraulic Road Disc (HRD) Brake Hose Shortening and Bleed Manual

Bleed Manuals

models: sb-red-hrd-b1

Table of Contents

Legend

Remove
Remove
Remove the component as indicated, either by hand or with a specified tool.
Apply Grease
Apply grease to lubricate and protect components from friction and/or moisture.
Torque
Tighten a fastener to a specified value, or apply a tightening force.
Install
Install the component in the indicated position by pressing, attaching, or placing.
Measure
Measure a length or distance to a specified value.

Tools and Supplies

Safety and Protection Supplies
Safety Requirements symbol
Safety Glasses
Nitrile Gloves
Apron
Shop Towels
Lubricants and Fluids
Hydraulic Brake Grease
DOT 5.1 / 4 Fluid
Bicycle Tools
Brake Hose Cutter
Bleed Block
Pad Spacer
DOT Fluid Syringes
Bicycle Repair Stand
Bicycle Repair Stand
Common Tools
Socket Wrench Icon
Socket Wrench
Open End Wrench
8, 10 mm
Crowfoot
8 mm
Hex tool icon
Hex Wrenches
2.5, 4, 5 mm
Hex Bit Socket
2.5, 4 mm
TORX icon
TORX Wrenches
T8, T25
TORX Bit Sockets
T10
Torque Wrench

General Safety

Safety Requirements symbol
Safety Instructions

You must read and understand the Safety Instructions document included with your product before proceeding with the installation. Improperly installed components are extremely dangerous and could result in severe and/or fatal injuries. If you have any questions about the installation of these components, consult a qualified bicycle mechanic. This document is also available on www.sram.com.

1. Follow the safety instructions listed here. Any failure to follow these safety instructions could cause you to crash while riding your bicycle, which could result in serious and/or fatal injuries.

2. SRAM hydraulic disc brakes are intended for single-rider use; they are not intended for multi-rider cycling equipment.

3. Have your brakes installed, secured, and maintained by a qualified bicycle mechanic.

4. Brakes are a safety-critical component of a bicycle. Improper installation or use of brakes can result in loss of control of the bicycle which can lead to a crash that can cause severe injury and/or death. Follow the instructions in the user manual for proper installation.

5. Disc brakes offer increased stopping power over rim brakes and take less effort to lock-up a wheel when braking. Wheel lockup may cause you to lose control and lead to injury. Practice braking techniques on a flat level surface prior to aggressive riding.

6. Braking effectiveness is dependent on many conditions over which SRAM has no control including: bicycle speed, braking force, condition of the bike, weight of the rider, weather, terrain, and a variety of other factors. Always ride under control. It takes longer to stop in wet conditions. To reduce the possibility of a crash avoid locking-up your wheels.

7. If using SRAM Mineral Oil brakes in temperatures below -20°C (-4°F), you may experience reduced braking performance. SRAM recommends using a SRAM DOT fluid hydraulic brake system if you ride at or below these temperatures.

8. SRAM disc brakes are designed as a system. Do not use brake components from a manufacturer other than SRAM.

9. Use only DOT 4 or DOT 5.1 brake fluids with SRAM DOT fluid hydraulic brakes. Use only Maxima Mineral Brake oil in SRAM mineral oil brakes. Use of any other fluid or oil may damage the system and make the brakes unsafe to use.

10. Do not allow any brake fluid or oil to contact the brake pads. If this occurs, the pads are contaminated and must be replaced.

11. Do not allow any brake fluid or oil to contact the rotors. If this occurs, clean the rotors with isopropyl alcohol.

12. Do not touch the braking surface of the rotor with your bare hands. The oils from your fingers will degrade braking performance. Always wear gloves or handle the rotor by the spokes.

13. Do not touch disc brake rotors or calipers immediately after use; they become very hot during use and could cause burns. Allow them to cool prior to making any adjustments.

14. Do not use SRAM hydraulic disc brakes with radially spoked wheels.

Warning

Do not use mineral oil. Use only DOT 4 or DOT 5.1 brake fluids with SRAM hydraulic brakes. Do not use any other fluid; it will damage the system and make the brakes unsafe to use, which could lead to serious injury and/or death.

DOT brake fluids will damage painted surfaces. If any fluid comes in contact with a painted surface, wipe it off immediately and clean with water. Used DOT brake fluid must be recycled or disposed of in accordance to local and federal regulations.

Never pour used DOT brake fluid down a sewage or drainage system or into the ground or body of water.

Use only DOT brake fluid compatible grease.

Notice

SRAM components are designed for use only on pedal-powered or pedal-assisted bicycles (e-Bike/Pedelec).

Warranty and Trademark

Consult sram.com/service whenever a separate manual is referenced in this document.

Read the full warranty policy for your components at sram.com/en/service/warranty.

For information about trademarks used in this manual, visit sram.com/website-terms-of-use.

Tool List

Highly specialized tools and supplies are required for the replacement and maintenance of your SRAM components. We recommend that you have a qualified SRAM dealer work on your SRAM components.

Tools and Supplies

Safety and Protection Supplies
Safety Requirements symbol
Safety Glasses
Nitrile Gloves
Apron
Shop Towels
Lubricants and Fluids
Hydraulic Brake Grease
DOT 5.1 / 4 Fluid
Bicycle Tools
Brake Hose Cutter
Bleed Block
Pad Spacer
DOT Fluid Syringes
Bicycle Repair Stand
Bicycle Repair Stand
Common Tools
Socket Wrench Icon
Socket Wrench
Open End Wrench
8, 10 mm
Crowfoot
8 mm
Hex tool icon
Hex Wrenches
2.5, 4, 5 mm
Hex Bit Socket
2.5, 4 mm
TORX icon
TORX Wrenches
T8, T25
TORX Bit Sockets
T10
Torque Wrench

Bleed Blocks and Pad Spacers

Force AXS (2025) / Rival AXS (2025) / RED AXS (2024+) / RED eTap AXS (2020-2024) / Force eTap AXS (2020+) / Rival eTap AXS (2021+) / Apex AXS and Apex (2023+) / S-900 Aero HRD (2021+)

Bleed Block
Pad Spacer

Red eTap AXS (2020-2021) / Red eTap (2018-2019) / S-900 Aero HRD (2019-2021)

Bleed Blocks
Pad Spacer

RED (2014-2019) / Force (2015-2023) / Rival (2015-2023) / Apex (2017-2023) / S-700 (2014-2021)

Bleed Block
Pad Spacer

Universal Bleed Block

Remove the wheel from the bicycle according to the wheel manufacturer’s instructions.

1. Remove the brake pads as shown in the Prepare the Caliper section.

2. Fully extend the Universal Bleed Block.

2.5 mm

3. Install the bleed block into the caliper. Align the bleed block with the pad retaining bolt hole and install the pad retainer bolt.

4. Install the Pad Retainer Bolt.

5. Press down on the handle of the bleed block expanding the wedge until it cannot expand further.

Proceed with the bleed procedure.

2.5 mm

6. Remove the pad retainer bolt.

7. Remove the Universal Bleed Block.

8. Clean the pistons and caliper before installing the brake pads.

9. Install the brake pads as shown in the Install the Brake Pads section.

Rotor Wear

1. Fully extend the universal bleed block.

1.7 mm Min.
1.55 mm Min.

Use the appropriate slot to measure your rotors (1.55 & 1.7 Min.)

2. Use the slot to determine if the rotor is at the minimum recommended width it must be replaced.

Rotor wear will vary by product model. This is normal. Change the rotor when changing the pad material, or when the thickness is less than the minimum stated on the rotor: 1.55 mm for 1.85 mm rotors and 1.7 mm for 2 mm thick rotors.

Shorten the Brake Hose

Remove the wheel from the bicycle according to the wheel manufacturer's instructions.

Secure a shop towel under the hose at the hose connection point to absorb any DOT brake fluid that may drip when the hose is disconnected.

Notice

Do not allow DOT brake fluid to come into contact with brake pads or rotors. Contaminated brake pads or rotors can diminish brake performance.

Hose Connection Identification

Identify the hose connection location for your brake system by locating the compression nut at the lever (A) or at the caliper (B).

Notice

Make sure to cut the hose near the compression nut. Cutting the hose at the end with a crimped banjo will require replacement of the complete hose.

Notice

Do not engage the lever while the hose is removed. Engaging the brake lever will result in a loss of fluid.

Disconnect Hose - Compression Nut at the Lever

8, 10 mm
8, 10 mm

1-2. Place a 10 mm open end wrench onto the valve body, and an 8 mm flare nut wrench onto the compression nut to loosen and remove the compression nut and hose.

8 mm

1-2. Use a 3 mm hex wrench to loosen and remove the brake lever from the aerobar.

3. Use an 8 mm open end wrench to loosen and remove the compression nut and hose.

4. Remove the hose from the lever.

Disconnect Hose - Compression Nut at the Caliper

8 mm

1. Slide the hose boot up.

2. Use an 8 mm flare nut wrench to loosen and remove the compression nut.

3. Remove the hose.

Route the Hose

The brakes should be installed with the hose properly routed and secured to the bicycle. To determine where to cut the hose, hold the hose up to the connection point with a length that creates a gentle bend in the hose and allows the handlebar to freely turn from side to side.

For internally-routed frames, remove the compression fitting, insert the hose through the frame, determine the proper length, then cut the hose.

Cut the Hose

Notice

Cutting the hose introduces air into the brake system. You must bleed the brakes to ensure optimal braking performance.

A small amount of DOT brake fluid may drip from the hose when it is cut, this is normal. Immediately clean any DOT brake fluid that comes in contact with painted surfaces with water.

Shift-brake Lever

1. Use a hydraulic hose cutter to cut the excess hose at the shift-brake lever.

Do not cut the hose at the caliper.

S900 Aerobar

1. To determine where to cut the hose, measure 20 mm from the end of the aerobar.

2. Use a hydraulic hose cutter to cut the excess hose.

Do not cut the hose at the caliper.

Compression Nut at Caliper

1. Use a hydraulic hose cutter to cut the excess hose at the brake caliper.

Stealth-a-majig Hose Barb and Fitting Installation

Notice

Stealth-a-majig brake levers, identified by "Stealth-a-majig Only" printed on the brake lever, are only compatible with the Stealth-a-majig compression fitting.

Brakes without "Stealth-a-majig Only" printed on the brake lever, are compatible with traditional or Stealth-a-majig compression fittings.

A: Stealth-a-majig Hose Barb
B: Stealth-a-majig Compression Fitting
Warning

All SRAM brakes that use a compression fitting and hose barb must use a new SJ (Stealth-a-majig) hose barb and a new, red SJ compression fitting upon reassembly.

The factory may have installed a non-red SJ compression fitting, which functioned properly prior to disconnection. Upon reconnection, you must install a new SJ hose barb and a new, red SJ compression fitting.

Brake hoses assembled with non-Stealth-a-majig hose barbs and compression fittings will not function.

T8

1. Apply SRAM hydraulic disc brake grease to the hose barb threads.

2. Use a T8 TORX wrench to thread the Stealth-a-majig hose barb into the hose until it is flush with the end of the hose.

Notice

Do not overtighten the hose barb. Overtightening may cause damage to the hose liner.

3. Thread the compression fitting over the hose barb, counter-clockwise, until it is flush or slightly lower than the hose barb.

The compression fitting is reverse threaded.

4. Apply SRAM hydraulic disc brake grease to the compression fitting and compression nut threads.

Install Hose - Compression Nut at Lever

8, 10 mm
8 N·m 10 (71 in-lb)
8, 10 mm
8 N·m (71 in-lb)

1. Install the hose into the valve body while threading the compression nut by hand.

2. Use a 10 mm open end wrench to hold the valve body, and use an 8 mm flare nut wrench to tighten the compression nut to 8 N·m (71 in-lb).

8 mm
8 N·m 1 (71 in-lb)

1. Install the hose into the brake lever while threading the compression nut by hand.

2. Use an 8 mm flare nut wrench to tighten the compression nut to 8 N·m (71 in-lb).

Install Hose - Compression Nut at Caliper

8 mm
5 N·m (44 in-lb)

1. Install the hose firmly into the brake caliper while threading the compression nut by hand.

2. Use a 10 mm open end wrench on the banjo wrench flats, and use an 8 mm flare nut wrench to tighten the compression nut to 5 N·m (44 in-lb).

Proceed to the Bleed Instructions section for your brake caliper type.

Notice

Cutting the hose introduces air into the brake system. You must bleed the brakes to ensure optimal braking performance.

A small amount of DOT brake fluid may drip from the hose when it is cut, this is normal. Immediately clean any DOT brake fluid that comes in contact with painted surfaces with water.

Bleed Instructions

SRAM recommends to bleed your brakes at least once a year to ensure optimal braking performance. Bleed your brakes more often if you ride frequently or ride on aggressive terrain that requires heavy braking. SRAM brake bleed videos can be found on sram.com/service

Caliper Identification

Bleeding Edge Bleed Procedure
Non-Bleeding Edge Bleed Procedure

Identify the bleed procedure for your brake by locating the bleed port on your caliper.

Calipers with a bleed port (A) located outside of the caliper body bolts and farthest from the hose connection utilize the Bleeding Edge Bleed Procedure.

Calipers with a bleed port (B) located either near the hose connection or between the caliper body bolts (C) utilize the Non-Bleeding Edge Bleed Procedure.

Proceed to the Bleed Procedure section for your brake caliper type.

Syringe Storage

Notice

Store used bleed syringes with DOT brake fluid in the syringe hose and the clamp open to extend the life of the syringe hose. Used syringe hoses can become cloudy and brittle if left empty.

Empty the syringe and use fresh DOT brake fluid before you begin a new bleed procedure.

Use only DOT 4 or DOT 5.1 brake fluids in the syringes. Do not use syringes that have come in contact with any other fluid.

Disc Brake Troubleshooting

Disc Brake Piston Massage

Notice

Do not apply DOT brake fluid or grease to caliper pistons when performing troubleshooting procedures. Use of DOT brake fluid or grease can diminish braking performance and cause rotor rubbing.

If your brakes exhibit excessive lever throw or spongy feel, perform the following steps before bleeding the system:

1. Clamp the bicycle into a bicycle work stand.

2. Remove the wheel from the affected caliper.

3. Remove the brake pads. Measure the brake pads for wear. If the pads measure less than the minimum thickness, replace the pads.

4. Re-install the pad retainer bolt.

5a. For road brakes: Install the Piston Massage Spacer or the thicker side of the appropriate pad spacer through the caliper between all pistons.

5b. For MTB brakes: Install the Piston Massage Spacer or two 1.85 mm thick rotors through the caliper between all pistons.

6. Squeeze the brake lever several times until the pistons have advanced and contact the spacing device being used. One piston may move faster than the other; that is okay. Continue to squeeze the lever until the pistons touch the spacer.

7. Remove the Piston Massage Spacer, pad spacer, or two 1.85 mm thick rotors.

8. Use a plastic tire lever to push the pistons back into the caliper bores.

9. Repeat steps 5-8 until the pistons move freely.

10. Remove the spacer and pad retainer bolt from the caliper and reinstall the brake pads.

11. Install the thinner side of a pad spacer between the brake pads.

12. Squeeze the brake lever lightly 5 times (approximately 4 lbs.) until the pads contact the spacer. Remove the spacer.

13. Install the wheel.

14. Loosen the caliper mounting bolts.

15. Lightly squeeze (approximately 4 lbs.) the brake lever several times to position the brake pads to the proper distance from the rotor.

16. Center the caliper on the rotor, and tighten the caliper mounting bolts to the torque specified in the appropriate user manual.

17. Spin the wheel and check the brake function. The pistons should move freely and there should not be excessive brake lever throw.

Notice

If there is no improvement in brake function or reduction of excessive lever throw, you must bleed the system. If a system bleed does not resolve the brake function, then a caliper service may be necessary. Consult your Disc Brake Service Manual for instructions.

Disc Brake Pad Gap Reset

Notice

Do not apply DOT brake fluid or grease to caliper pistons when performing troubleshooting procedures. Use of DOT brake fluid or grease can diminish braking performance and cause rotor rubbing.

If the brake lever was squeezed without a pad spacer or rotor installed in the caliper, the pad gap may have been reduced. If this happens the rotor might not have enough clearance in the caliper to rotate without rubbing. Perform this procedure to reset the pad gap:

  1. Remove the wheel from the affected caliper.

  2. Install the thicker side of a pad spacer between the brake pads.

  3. Squeeze the brake lever hard 5 times (approximately 22 lbs/10 kg).

  4. Remove the spacer from the caliper, and install the thinner side of a pad spacer between the brake pads.

  5. Squeeze the brake lever lightly 5 times (approximately 4 lbs or less).

  6. Remove the pad spacer.

  7. Re-install the wheel, and re-center the caliper.

Disc Brake Pad Retraction Reset (Monoblock Caliper Only)

Notice

Do not apply DOT brake fluid or grease to caliper pistons when performing troubleshooting procedures. Use of DOT brake fluid or grease can diminish braking performance and cause rotor rubbing.

If there is still insufficient clearance between the brake pads and rotor after performing the pad gap reset procedure, perform this overnight procedure to reset the retraction distance between the caliper pistons:

1. Remove the wheel from the affected caliper.

2. Install the 3.8 mm side of a pad spacer between the brake pads and remove it without squeezing the brake lever.

3. Install the 2.4 mm side of a pad spacer between the brake pads.

4. Squeeze the brake lever lightly 5 times (approximately 4 lbs or less).

5. Allow the system to sit, untouched, for 12-24 hours.

6. Remove the pad spacer.

7. Re-install the wheel, and re-center the caliper.

Bed-in Procedure

All new brake pads and rotors should be put through a wear-in process called 'bed-in'. The bed-in procedure, which should be performed prior to your first ride, ensures the most consistent and powerful braking feel along with the quietest braking in most riding conditions. The bed-in process heats up the brake pads and rotors, which deposits an even layer of brake pad material (transfer layer) to the braking surface of the rotor. This transfer layer optimizes braking performance. To watch a video of the bed-in procedure, visit: SRAM: Disc Brake Bed-In Procedure.

  1. Accelerate the bike to a moderate speed, then firmly apply the brakes until you are at walking speed. Repeat approximately twenty times.

  2. Accelerate the bike to a faster speed, then very firmly apply the brakes until you are at walking speed. Repeat approximately ten times.

  3. Allow the brakes to cool prior to any additional riding.

  4. After the bed-in procedure has been performed, the caliper may need to be re-centered.

Warning

CRASH HAZARD

The bed-in process requires you to perform heavy braking. You must be familiar with the power and operation of disc brakes. Braking heavily when not familiar with the power and operation of disc brakes could cause you to crash, which could lead to serious injury and/or death. If you are unfamiliar with the power and operation of disc brakes, you should have the bed-in process performed by a qualified bicycle mechanic.

To safely achieve optimal results, remain seated on the bike during the entire bed-in procedure. Do not lock up the wheels at any point during the bed-in procedure.