Bike Repair – How to Bleed SRAM Guide Brakes

Follow these 16 simple steps to get your SRAM Guide R, RS, RSC or DB5 disc brakes working at their best.

1. Remove the pads

Clamp your bike in a workstand and remove the wheel and brake pads. Use the ring end of a 12mm spanner to carefully push the pistons back into their bores, then wedge a plastic bleed spacer between them. Thread the brass adapters onto the syringes. Put on safety glasses and gloves, then use fresh DOT 5.1 brake fluid to half fill one syringe and quarter fill the other.

2. Set up the syringes

Turn one of the syringes upside-down. Hold a rag around the end in case of spillage and press the plunger. Once any trapped air has been expelled close the red plastic clip to lock the syringe. Now pull the plunger to create a vacuum. Hold it for 30 seconds while flicking the syringe to draw out any air bubbles. Unlock the red clip, then squeeze out any air again.

3. Remove bleed port screw

Repeat step 2 on the second syringe. Now you’re ready to attach both syringes to the brake. Use a T10 Torx key to loosen and then remove the bleed port screw on the side of the calliper, turning it anticlockwise. Put it somewhere safe. Double check the half-full syringe to make sure there’s no air still inside before attaching in step 4…

4. Attach the syringe

Take the half-full syringe, making sure that the fluid has been pushed right to the tip and is free of air bubbles, and that the red plastic clip is closed. Screw the brass fitting on the end of the syringe into the open calliper bleed screw port, turning it clockwise. It only needs to be finger tight because the O-ring on the threaded adapter will create a seal.

5. Position the lever

Rotate the lever on the bar so the blade points down at 45 degrees from horizontal – you’ll need a T25 Torx key to loosen and then retighten the clamp bolt. Turn the lever reach adjuster clockwise until it stops, then turn it anticlockwise two full turns. On Guide RSC brakes, also wind the contact point adjuster in the opposite direction to the arrow until it stops.

6. Attach the syringe

Make sure all the air is removed from the second syringe and that the red plastic clip is closed. Use a T10 Torx key to remove the bleed port screw from the lever, turning it anticlockwise. Put it somewhere safe. Attach the syringe, turning the brass fitting clockwise until it’s finger tight. Check you’ve completed steps 3 to 6 correctly.

7. Purge the system

Release the red plastic locks on both syringes. With the calliper syringe held vertically, press the plunger, pushing until you’ve emptied around half of the fluid into the system. This should leave the calliper syringe a quarter full and the lever syringe half full. It’s important not to empty the caliper syringe or overfill the lever syringe.

8. Lock out the lever

Now the lever and calliper can be vacuum bled to remove any remaining air. Close the red clips on the lever syringe. Wrap a toe strap or rubber band around the bar and the brake lever, ensuring that it clamps the lever tightly and securely against the bar. This will lock out the lever, isolating it so that you can bleed air from the calliper.

9. Bleed the calliper

Holding the calliper syringe vertically, pull on the plunger to create a vacuum and then tap the caliper with a blunt plastic object. Bubbles should emerge from the calliper and rise into the syringe. When they stop, push the plunger back in. This will reintroduce fluid into the system where the air has been removed. Repeat until there’s no more air leaving the calliper.

10. Repressurise the system

It’s now time to remove the toe strap or rubber band, making sure that you keep the lever blade pressed to the bar with your other hand while you do so. Once the strap/band is off, apply pressure to the calliper syringe plunger and slowly release the brake lever. Continue to apply pressure as the lever returns gradually to its original position, pressurising the system.

11. Refit bleed port screw

Close the red plastic clips on both syringes. Making sure that the calliper bleed screw you removed earlier is close to hand, remove the calliper syringe by unscrewing the brass bleed fitting, turning it anticlockwise. With the T10 Torx tool, replace the bleed screw quickly, being careful not to introduce any air into the system.

12. Clean the calliper

DOT brake fluid is harmful to your skin and to your bike’s paintwork, so make sure to clean up any spillages as you go, using brake cleaner (or water) and a rag. The chances are that some fluid will have dripped from the calliper while the syringe was being removed, so make sure to give it a thorough clean now.

13. Bleed the lever

Unlock the red plastic clip on the lever syringe hose. Holding the syringe vertically (with the brass adapter downwards), pull on the plunger to create a vacuum and then push it back in to pressurize the system. Flick the brake lever a few times. Repeat this step until there’s no more air or only the tiniest amount escaping into the syringe.

14. Refit bleed screw

Sit the lever bleed screw atop the T10 Torx tool ready for reinstallation. Push the plunger down one last time before unscrewing the brass fitting from the brake lever. Refit the bleed screw, losing as little fluid as possible and making sure not to introduce any air into the system. Fluid will be lost, so don’t fret – concentrate more on keeping air out.

15. Clean up the lever

Now the brake is air free and successfully bled, it’s time to clean up. Use brake cleaner (or water) and a rag to wipe any areas that have been in contact with brake fluid. Remove the bleed spacer from the calliper and give the calliper a good clean too. It’s also a good idea to clean any tools that have come into contact with the fluid. Take off your gloves.

16. Refit the brake pads

Refit the brake pads, using a plastic pad separator tool to space them correctly. Reinstall the wheel. Return the lever to its original angle, reach and contact point settings. Squeeze it repeatedly to check for a solid, crisp feel. Realign the calliper by loosening the 5mm Allen bolts that hold it to the fork or stay, squeezing the lever and then retightening the bolts.

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