Mini Info Bomb: SRAM and Shimano hydraulic brakes require a different bleeding process. The bleeding kits designed for each brand reflect the dissimilarities.
That said, it’s possible to use parts of a SRAM bleed kit on Shimano brakes and bleed them successfully.
Nonetheless, it’s advisable to acquire a proper Shimano bleed kit for a more convenient, safer, and faster bleeding process.
Also, do not rely on a used SRAM kit to bleed Shimano brakes because the two systems use different fluids, and there are chances of contamination.
Differences Between SRAM and Shimano Brake Bleeding
An average Shimano bleed kit includes the following parts:
- a syringe
- a hose with a compression sleeve/slip stopper
- a funnel
- a plug for the funnel
- a drain hose
- a drain bag or bottle
- bleed blocks
The bleeding process of Shimano flat bar hydraulic brakes is as follows:
1. Bring the brake lever away from the grip as much as possible via the reach adjustment screw.
2. Position the bike in a way that will ensure consistent travel of fluid between the caliper and the brake lever. If you’re bleeding the front brake, just putting the bike in a stand will be enough.
If you’re bleeding the rear brake, the movement of the fluid can be facilitated by lifting the front end of the bike and positioning the entire frame perpendicularly to the floor.
3. Remove the brake pads and put them in a place where they cannot be contaminated.
Tip: Wrap the brake pads in a clean, dry paper towel.
4. Put the pistons into the caliper body via a special tool or tire levers and then slide a bleeding block between the pistons. Thread the screw originally holding the pads through the block.
5. Remove the bleed port screw on the brake lever and the O-ring around it.
6. Thread the bleed funnel into the bleed port.
7. Rotate the brake lever until the funnel is at 45 degrees.
8. Thread the threaded part of the hose onto the syringe.
9. Install a compression sleeve on the other end of the hose.
10. Draw mineral oil into the syringe until it’s 2/3 full.
11. Push the plunger until the fluid in the syringe reaches the tip of the hose.
12. Put a 7mm box-end wrench on the bleed nipple and then slide the hose onto it. Slide the compressing sleeve on the nipple to stabilize the set-up.
13. Open the nipple with the wrench.
14. Loosen the bleed port screw on the caliper.
15. Start pressing the syringe until most of its fluid goes to the funnel attached to the lever.
16. Continue pushing until the fluid in the funnel is clean and there are no air bubbles.
18. Close the bleed nipple of the caliper by tightening it with the 7mm box end wrench.
19. Remove the syringe.
20. Remove the funnel and dispose of the fluid appropriately.
21. Re-install the funnel with a stopper onto the lever.
22. Remove the stopper and fill the funnel with mineral oil.
23. Attach one end of a hose to a disposable plastic bag or cup. Attach the other end to the bleed nipple on the caliper.
24. Open the nipple with the box end wrench and press the brake lever gently.
25. As fluid starts going from the funnel to the draining hose, you will see air bubbles. Keep filling the funnel until there are no more air bubbles.
26. Close the bleed nipple on the caliper.
27. Rotate the lever until it forms a 30-degree angle with an imaginary vertical line. The goal of this step is to eliminate air stuck into the connecting port inside the brake lever. Squeeze the lever to get rid of the air.
28. Plug the funnel and remove it.
29. Install the lever bleed screw and O-ring.
30. Adjust the lever’s position.
31. Install the pads.
A SRAM bleed kit includes:
2 x syringes
2 x fittings
1 x bleeding edge tool for S4 (Guide Ultimate)
4 x SRAM hose nipples
4 x SRAM clamp rings
1 x SRAM T10/T25 tool
1 x crow’s foot
1 x O-ring set
The bleeding process of SRAM flat bar hydraulic brakes is as follows:
- Remove the wheel and the brake pads.
- Install a bleed block.
- Fill 2/3 of the syringe that goes into the lever with the appropriate DOT fluid. Get the air out. Make sure that the hose clamp is closed and preventing oil from exiting the hose.
- Fill 1/5 of the syringe that goes into the caliper with the appropriate DOT fluid. Get the air out. Make sure that the hose clamp is closed and preventing oil from exiting the hose.
- Rotate the brake lever until it’s horizontal and the bleed nipple is pointing up.
- Adjust the reach adjustment of the lever until the lever’s end is 75-80mm away from the center of the grip.
- Remove the bleed screw.
- Thread the syringe prepared for the lever into the bleed port.
- Push the bleed edge tool into the caliper.
- Open the system by unscrewing the bleed port on the caliper.
- Start the bleeding process by slowly pressing the plunger of the brake lever syringe. Continue until there are no air bubbles coming out of the caliper end.
- Hold the caliper syringe vertical and then draw out fluid via the syringe going into the brake lever (essentially reversing the process).
- Close the caliper end.
- Push fluid through the brake lever syringe to pressurize the system and then back it out a couple of times.
- Lock the clamp on the brake lever hose.
- Remove the brake lever syringe.
- Close the bleed port on the brake lever.
- Remove the bleed edge tool and close the bleed port on the caliper.
- Install the pads.
The Difference Between Shimano and SRAM Brake Bleeding
The main difference is that Shimano brakes use a funnel rather than a syringe on the brake lever side.
To mimic that with a SRAM bleeding kit, you can remove the plunger from the brake lever syringe and leave the syringe open. At that point, it’s essentially a funnel.
You will also have to figure out a way for the brake lever syringe to stay vertical. One option is to have someone hold it for you. Otherwise, you will spill mineral oil all over the place and contaminate the bike and the room.
From that point, you can continue with the procedure using the other syringe at the caliper end of the bike.
Even though people have successfully bled their brakes this way, this method has notable inconveniences and risks, namely:
- The bleeding process is a procedure that is rarely as clean as the videos show. By improvising with improper equipment for the job, you’re making a difficult drill even less comfortable.
- By relying on non-standard tools, you’re creating an opportunity to lose the warranty of your components.
Additional warning
Shimano hydraulic brakes use mineral oil whereas SRAM brakes rely on DOT fluid.
The two fluids are not interchangeable. If you put mineral oil in a SRAM system or DOT fluid in a Shimano one, the seals of the brakes will be damaged and the components will fail.
For that reason, it’s not recommended to utilize a used SRAM bleeding kit on a Shimano system because there’s a slight chance that it will contaminate the system with small particles of DOT fluid.
Summary: What You Need To Know
1. Shimano bleed kits use a funnel at the brake lever end whereas SRAM’s kits rely on two syringes.
2. It’s technically possible to use a SRAM kit on a Shimano brake if you remove the plunger from the brake lever syringe and use the syringe as a funnel. However, the process is a lot more comfortable if you rely on an actual funnel.
3. SRAM and Shimano use different hydraulic fluids. Mixing the fluids will result in brake damage and failure.
