Brake Bleeding for SRAM® Bleeding Edge Hydraulic Brakes Using the BKD-1

This article will review the bleeding procedure for SRAM® hydraulic brakes with Bleeding Edge, while using the Park Tool BKD-1 Bleed Kit.

1

Preliminary Info

This bleeding procedure will work on SRAM drop bar and flat bar brakes that feature Bleeding Edge. See this article for the non-Bleeding Edge procedure.

Brake bleeding is considered an advanced service procedure, and requires a thorough technical knowledge of the braking system. If in doubt, or if this procedure is not working, contact the brake manufacturer for model-specific information.

It is important to always use the appropriate brake fluid for the brake being serviced. Never use mineral oil in brakes designed for DOT brake fluid, or vice versa. Never share bleed kits between DOT fluid and mineral oil systems. Mixing fluids can cause damage to components and lead to brake failure, which is dangerous.

DOT fluid is corrosive, and it can irritate the skin and eyes, and damage paint and other finishes - so it is important to take care. Wear gloves and eye protection during this procedure. Have plenty of rags handy for wiping up spills as quick as possible. Isopropyl alchohol is a good cleaner to help clean and neutralize the DOT fluid, if spilled. You may want to also cover your work area to avoid getting fluid on the floor.Dispose of any spent fluid in accordance with your local waste disposal authorities

2

Bicycle Prep

  1. Install the bike in a repair stand if available.
  2. Begin by prepping the lever.

Flat Bars:

    • If your flat bar lever is equipped with a contact adjuster, turn it opposite the arrow until it stops.
    • Measure the amount of reach from the centerline of the handlebar to the tip of the brake lever. To bleed it needs to be between 75mm and 80mm. if not, make note of your current adjustment and then adjust to between 75mm and 80mm. On some models, this is a tool-free adjustment, while other models require a hex wrench.
Closeup of brake lever contact adjuster being turned counterclockwise by hand

Turn contact adjuster until clicking stops

SBC-1 being held across center of handlebar and tip of brake lever to measure distance

Tip of lever should fall between 75-80mm from center of handlebar

Drop bars:

    • For drop bars with a contact adjustment, pull back the cover and use a 5mm hex to turn the adjustment counter clockwise till it stops.
Drop handlebar brake lever with hood pulled back and hex wrench dialing contact adjuster counterclockwise
  1. Tie a rag around the lever to catch any spills.
  2. Remove the wheel.
  3. Use a pad spreader such as the PP-1.2 to push the pads back to allow for the bleed blocks once the pads are removed.
Drop handlebar brake lever prepped with hood pulled back and prepped with rag

Lever prepped with rag

PP-1.2 being used to spread brake pads in hydraulic caliper in preparation for bleed blocks

spread pads to allow for bleed blocks

  1. Angle the bike in the stand so that the path of the hose from the caliper to the lever is consistently traveling upwards. It can also help to remove the caliper and let it hang, especially for rear calipers. This makes the path for air bubbles as easy as possible to follow.
Rear brake caliper unmounted from bike and hanging off of frame to position hose at angle
Position bike and caliper to minimize downward or lateral travel of brake hose
  1. The pads are removed to prevent any contamination.
    1. Remove the pad pin clip with a needlenose pliers, and unthread the pad pin with a 2.5mm hex wrench.
    2. For pads with a split cotter pin, use a needlenose pliers to straighten the pin, then pull it out.
Removing clip and unthreading pin from hydraulic brake caliper with threaded pin

threaded pad pin: remove clip and unthread pin

Bending cotter pin to remove from hydraulic brake caliper

cotter pin: bend pin straight and remove

  1. Pull the pads out. It can help to push from the bottom initially.
  2. install the bleed block and secure with either the pad pin, a rubber band or a zip tie.
    1. If the caliper has two sets of pistons, use both bleed blocks.
Removing brake pads from hydraulic brake caliper by hand

Remove pads by hand

Two bleed blocks installed into a hydraulic brake caliper on a rigid bicycle fork

Caliper with two sets of pistons

  1. Attach the syringe holder above the caliper.
3

Bleed Kit Prep

  1. Install the double ended hoses onto the syringes, with the o ring capture away from the syringe.
  2. Install the red adaptor end (part #2618) onto one syringe hose.
Hose being finger threaded into brake bleeding syringe

Thread double-ended hoses into syringes

Finger threading adaptor #2618 onto syringe hose

Thread adaptor #2618 onto first hose

  1. This will be the lever syringe. Fill it to 1/2-3/4 full.
Brake bleeding syringe using hose to draw hydraulic brake fluid out of a container
draw fluid directly from container
  1. Hold the hose end up and push the syringe. Eliminate as much air as possible. Clip the hose.
Syringe being held upside down with hose lifted up to allow bubbles to escape

Hold syringe upright

Rag being held against syringe hose end while pushing out air bubbles

push until no air remains in hose

  1. Install the Bleeding Edge adaptor end (#2612) on the other syringe.
Bleeding Edge adaptor #2612 installed on second syringe hose end
Bleeding Edge adaptor (#2612) on second hose
  1. This will be the caliper syringe. Fill it 1/4 full.
  2. Repeat the process of eliminating air from the hose and clipping the hose.
  3. Remove the bleed screw from the lever using a Torx®-compatible T10 wrench. There is an o-ring on this screw - make sure it also comes out.
  4. Install the 3/4 full syringe into the lever. Ensure the o-ring is seated fully and evenly in the capture of the bleed port as you thread in the adapter. Clean up any spilled fluid right away.
Closeup of O-ring on bleed bolt after removed from brake lever bleed port

Ensure that o-ring is removed along with bleed screw

Adaptor end of syringe hose being installed into brake lever bleed port

Fully thread syringe into bleed port

  1. At the caliper, remove the rubber cap from the bleed port. Use a 4mm hex wrench to loosen the Bleeding Edge port, then snug it back up just slightly.
  2. Insert the Bleeding Edge adaptor into the caliper. It will snap into place.
Closeup of brake caliper with Bleeding Edge port being loosened and retightened by a hex wrench

Loosen then re-snug Bleeding Edge port

Closeup of syringe hose end with Bleeding Edge adaptor being inserted and snapped into port on brake caliper

Snap Bleeding Edge adapter into caliper

  1. Install the caliper syringe into the holder.
4

Bleeding

  1. Unclip both syringes.
  2. Open the Bleeding Edge port by loosening 1 full turn.
Bleeding Edge adaptor being held and rotated counterclockwise to loosen port on brake caliper
Keep adaptor engaged while turning
  1. Push on the lever syringe. Do this until there is about 1/4 a syringe of fluid in the lever syringe and about 3/4 in the lower.
Clean brake fluid being pushed out of the upper syringe and dirty fluid entering the lower syringe
As fluid is pushed into the system, it will push excess fluid into the caliper syringe

NOTE: If the fluid coming out is dirty or discolored, push all fluid to the lever syringe, remove the syringes, refill and start the bleeding process over. This will ensure that you brake system has clean fresh fluid.

Closeup of bleed syringe with dirty fluid entering
Dirty fluid entering syringe
  1. Use the lever syringe to pull the fluid back up to the lever syringe. The vacuum created will dislodge air bubbles. Be careful not to pull too hard and pull air past the syringes.
Upper syringe pulling up plunger to draw air bubbles out of system

Draw fluid back through the system

Air bubbles leaving braking system through syringe hose end at brake lever

Bubbles escaping system via lever syringe

  1. Close the Bleeding Edge port.
Bleeding Edge adaptor being held and rotated clockwise to tighten port on brake caliper
Tighten bleeding edge port until snug
  1. Squeeze the brake lever 3 times.
  2. Pull back on the lever syringe to create a vacuum, then push on the syringe to create pressure in the system.
  3. Repeat steps 6-7. Do this procedure till you see no bubbles or very few bubbles escaping via the lever syringe hose.
Hand depressing brake lever on drop handlebars

Fully squeeze lever 3 times

Bleed syringe being held in hand and the plunger pulled, then pushed

Pull to create suction/push to create pressure

  1. Push on the syringe one last time to equalize the pressures.
5

Reset Bicycle

  1. Clip and remove the lever syringe.
  2. Install the bleed port screw. Torque to 1.5-1.7 Nm.
  3. Clean up any spilled fluid with isopropyl alcohol.
    Bleed port screw on brake lever being tightened by a Torx® compatible wrench

    Snug bleed port screw

    Brake lever being sprayed with rubbing alcohol, especially around bleed port

    Clean and wipe all surrounding areas

    1. Reset the lever reach to users preference
    2. For drop bars, pull hood back into place.
    3. At the caliper, tighten the Bleeding Edge adapter then pull the adapter off.
    4. Once the adapter is removed, torque the fitting to 1.5-1.7 Nm with a hex wrench.
    5. Remove the bleed blocks and clean out the caliper body with alcohol
    Snug bleeding edge port

    Snug bleeding edge port

    Brake caliper being sprayed with rubbing alcohol

    Clean and wipe all surrounding areas

    1. Reinstall the pads, pad pin and clip.
    2. Reinstall the wheel.
    3. Pull the brake lever 3 times to set the pads.

    NOTE: If you encounter rubbing, you may need to realign your calipers at this time.

    6

    Clean Kit

    1. After bleeding, clear the syringes and hoses of all fluid.
    2. To prolong the life of your bleed kit, it’s recommended to clean the whole system with alcohol. Start by running alcohol through the hoses.
    Bleed syringe being held with two hands with the hose end emptying used fluid into a waste container

    Empty spent fluid into appropriate container

    A bleed syringe held in one hand and hose end in the other, working alcohol back and forth

    Pour alcohol into syringe assembly and run back and forth

    1. Disassemble the kit and wipe down each piece, especially the parts that came into contact with DOT fluid.
    Threaded hose end being sprayed with rubbing alcohol

    Thoroughly clean all threaded ends

    Bleed syringe with plunger removed, with clean rag inserted into the body for cleaning

    Thoroughly wipe all surfaces

    1. Leave the kit out to dry.
    2. Dispose of fluid in accordance with local regulations (see resources for: US, UK)