SRAM® HydroR™ Brake Service Tips and Tricks
Cyclists are always looking for a way to improve their ride: a way to dial in their bike to gain the highest performance possible. Getting the most out of your SRAM® HydroR™ brakes is easy if you follow a few basic rules. From installation to bleeding, adjustment, and maintenance − we’ve got all the bases covered in this list of tips and tricks to help you stay safe and get your brakes set up right.
1. Installation: Always use a torque wrench
This is important not just for the caliper mounting bolts (5-7 N∙m torque spec for post mount and 4.8-5.2 N∙m for flat mount), but also for the compression nuts (5-6 N∙m torque spec) where the hose attaches to the caliper banjo. It is especially important to use a torque wrench where the hose attaches to the lever assembly, as this attachment can be easily stripped if torqued beyond 3.9 to 4.4 N∙m.
As you work, keep in mind that it requires several turns at a torque close to the final torque (5-6 N∙m) to properly seat compression nuts. When fully compressed there should be 2-3 threads showing between the fitting the nut threads into and the head of the nut.
2. Maintenance: Follow the bleed procedure
Not following the bleed procedure can damage primary seals in the lever, which can lead to leaks or brake failure. Another common problem caused by not following the bleed procedure is an overfilled master cylinder reservoir. This removes any negative space in the reservoir leaving no room for the brake fluid to expand when it gets hot. Then when the brake gets hot, the expanding fluid will cause the caliper pistons to clamp down on the rotor thereby creating brake drag or even lockup. Overfilled master cylinder reservoirs can also leak brake fluid, causing damage to primary seals in the lever assembly and damage to the finish of the lever where the brake fluid leaks out.
3. Service your caliper pistons
Over time caliper pistons can get sticky and no longer advance properly. This can lead to low braking power, a spongy lever feel, uneven pad wear, and noise.
Fixing the problem is often as easy as performing a piston advance. This can be accomplished by first removing the wheel and taking the brake pads out of the caliper; then using a plastic tire lever, push one piston in while you squeeze the brake lever. This will force the other piston to advance. After the piston advances, use the tire lever to press the piston back into the caliper to its original position. Repeat the process on the other side. Do this to both pistons three to four times and the pistons will free up and advance properly. When performing a piston advance be careful not to advance the piston so far that it falls out of the caliper. If you do accidentally eject a piston, you can carefully reinstall it by pressing it back into the piston bore. When doing this, be careful to install the piston in the correct orientation.
Even if your brakes don’t have a piston advance problem, performing this procedure every time you replace your brake pads is a good preventative maintenance practice.
If a piston advance doesn’t free up the caliper pistons to advance and retract properly, a caliper overhaul is required. This service procedure includes replacing caliper piston seals.
4. Only use SRAM parts
Like many other high-end parts on modern bikes, SRAM HRD brakes are made to perform using only original equipment replacement parts.
Rotors: Non-SRAM rotors typically create excessive noise, brake pulse, and overheating.
Brake pads: SRAM brake pads will keep your brakes quiet while offering the best balance of power and control.
Hose compression olives and fittings: Non-SRAM compression olives and fittings create leaks that can be hard to diagnose because they are often small. However, the problem can still lead to brake failure, so be sure never to make this mistake.
Brake fluid: Always use DOT 5.1 brake fluid. Don’t ever use mineral oil or DOT 5 brake fluid in a SRAM brake. They will destroy the brake’s seals, eventually causing brake failure and requiring replacement of the entire brake. Although DOT 3 and DOT 4 brake fluid are compatible with SRAM brakes, the brakes are designed around the highest performing DOT brake fluid available, DOT 5.1. This brake fluid has a higher boiling point than DOT 3 or DOT 4 for top performance on the most demanding descents.
5. Dial in your fit with reach adjust
Get more power and control from your SRAM brakes by adjusting them to fit your hands. The adjustment is located between the shift lever blade and the brake lever blade on the underside of the brake lever. Pull back the shift lever to access the 2.5mm hex adjustment screw. When viewed from the bottom, turn the wrench clockwise to move the lever away from the bar and turn the wrench counter-clockwise to move the lever closer to the bar. Once you have your adjustment made, check to make sure that when the brake lever is pulled firmly, it doesn’t bottom out on the handlebar, limiting your braking power.
6. Bed in your brakes properly before riding
When pads and rotors are new, they have to be “bed in” before they reach their full braking potential. This is achieved by first accelerating the bike to a moderate speed and then firmly applying the brakes until you are at walking speed. Repeat this process 20 times. Then accelerate the bike to a faster speed and apply the brakes until you are at walking speed. Repeat this process ten times. It’s important that during this process you never come to a complete stop or lock up the wheels at any point. The idea behind bedding in a brake is to evenly distribute pad material across the rotor to improve the coefficient of friction between the two components. Coming to a complete stop causes a build up of pad material in one spot that can lead to pulsing and noisy brakes.
7. Know when to replace your brake pads and rotors
Waiting too long to replace brake pads causes rotor damage, noise, and reduced braking power. Inspect your brake pads regularly to ensure that the overall thickness of the individual brake pads measures at least 2.5mm thick including the pad’s backing plate. When a rotor measures less than 1.55mm thick it needs to be replaced.
8. Select the right brake pad for your riding conditions
SRAM HRD brakes come stock with steel-backed organic brake pads. These are the best option for most road riding conditions and offer the best balance of power and control. SRAM also makes steel-backed sintered metallic brake pads for extremely muddy conditions, typically encountered in cyclocross racing. These sintered metallic pads are longer wearing and are ideal for use when abrasive mud causes excessive pad wear. Keep in mind that while sintered pads offer better wear resistance, they do a poor job of dissipating heat. So for general road riding, organic brake pads are required to avoid brake fade.
When selecting brake pads, be sure to use a dedicated set of brake rotors for each type of brake pad compound. So if you make the switch from one type of pad material to another, your brake rotors need to be swapped as well.
For all SRAM Road tech manuals visit the SRAM Road Service Page.
For more videos on how to set up SRAM HydroR disc brakes, visit the SRAM Tech YouTube channel.