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How to Service SRAM AXS Road Disc Brakes

Aug 29, 2023

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Use these tips to keep your SRAM AXS road and gravel disc brakes running smoothly

SRAM’s AXS drivetrains and disc brakes are equipped on tons of new road and gravel bikes and are a popular upgrade for riders seeking improved shifting and braking performance. However, for many riders new to road disc brakes, servicing this tech might seem confusing or overwhelming.

Recently, I took a trip to SRAM’s Indianapolis, Indiana training facility to learn first-hand about all things SRAM. Diving into the topic helped ease my anxieties about servicing these high-performance stoppers.

First, we specifically look at the rider-oriented benefits SRAM designed into its AXS wireless groupsets. Then, we jump into a step-by-step guide for bleeding SRAM two-piece road disc brakes regarding. There’s a lot of info here so buckle up folks!

Red AXS — Highest tier groupset shedding weight using higher-end materials

Force AXS — Higher quality products and a reduced weight

Rival AXS — Budget focused exclusively on wireless

Apex AXS & (Mechanical) — SRAM’s entry-level groupset with wired and wireless options

Before getting into the details of SRAM’s disc brakes, this is a recap of the brand’s AXS groups. AXS helps make wireless shifting accessible to more types of riders. The technology is offered at four different price levels and focuses on three key features, detailed below.

This provides wider gear ranges, smooth and progressive jumps between gears, and controllable shift settings. SRAM offers cassettes and chainrings in wide ranges, compatible with 1x or 2x depending on your bike and riding preference.

Orbit rear derailleur technology was developed by SRAM to dampen feedback and vibrations that the rear derailleur and chain see when riding. It provides smoother and crisp feeling shifts.

Think of this as a “clutch” mechanism that holds the chain and rear derailleur under tension. It dampens any bumps or inconsistencies that may affect the linear connection the drivetrain has under power.

This proprietary chain was developed by SRAM. It has a unique chain shape, that results in a stronger, quieter, and more durable chain.

The FlatTop chain is used exclusively on AXS road groupsets, The redesigned chain is a unique design—optimized for 12-speed groupsets—but is not compatible with other SRAM 12-speed drivetrains like Apex Mechanical, AXS Eagle, or Transmission groupsets.

Thanks to the AXS mobile app, control and adjustment of your AXS system are just a few clicks away. The app gives users fine-tuning control over their drivetrain system to maintain shifting precision, configure buttons, change shifting speeds, and much more.

This feature is for any riders with Bluetooth-enabled cycling devices and internet access. It will collect all of your data (like power, cadence, and number of shifts) to provide a deeper dive into your ride and what gains you could make.

These are the tools needed for the job. If you don’t have them, pick them up online or from a local shop before beginning

Important Notes—Bleed Blocks: Depending on the model of your brake, each model will use a slight variation of which bleed block you will need. Consult this diagram to know which you need.

Before starting the full bleed process, run through this set of troubleshooting tips and tricks.

If your brakes exhibit excessive lever throw or a 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.

4. Install the pad spacer.

5. Squeeze the brake lever several times until both pistons have advanced and contact the pad spacer. One piston may move faster than the other; continue to squeeze the lever until the second piston touches the spacer.

6. Remove the pad spacer.

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

8. Repeat steps 4-7 until both pistons move freely.

9. Reinstall the brake pads and the wheel.

10. Loosen the caliper bolts.

11. Lightly squeeze (approx. 4 pounds of pressure) the brake lever several times to position the brake pads to the proper distance from the rotor.

12. Center the caliper on the rotor and tighten the caliper bolts.

13. Spin the wheel and check the brake function.

After these steps, the pistons should move freely and there should not be excessive brake lever throw. If there is no improvement in the brake function, proceed to the service manual for your caliper.

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 (approx. 22 pounds of force for each pull).

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 (4 lb. or less).

6. Remove the pad spacer.

7. Reinstall the wheel and re-center the caliper.

Note: If the brake fluid in the syringe at the caliper is discolored, continue to push all the fluid out of the system. Restart the bleed procedure with new fluid in both syringes. Some assembly grease might be present in the DOT brake fluid of new systems. This can look like a floating substance in the DOT brake fluid. This does not affect the performance of the brake system.

Before you head off, bed your brakes per SRAM’s instructions to help reduce noise.

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