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Feature by Brandon Turman // Photos by Adrian Marcoux

If 2015 bike specs are anything to go by, people want the consistency, power, and ease of use offered by Shimano brakes. Vital's own audience survey showed the same trend. This likely left SRAM wondering how they get back a bigger piece of the braking pie. Well, you guessed it, SRAM is here to answer that call with their new Guide Ultimate brakes and some rather interesting new technologies that should trickle down into other models. Following a near complete rebranding from Avid to SRAM in 2014, SRAM has continued to put lots of effort into their brake lineup.

Are they up to snuff? Let's take a look at what's new before we hit the trails of Rotorua, New Zealand for a test ride.


Guide Ultimate Highlights

  • All-new caliper design
  • Updated lever
  • Colors: Arctic Grey Ano and Black Ano
  • Weight: 360g (front brake, includes 160mm rotor, hose, clamp, adapter and all bolts)
  • Available: May 2015
  • Pricing: $288 USD per brake, plus $72-78 per CenterLine X rotor

When the Guide line of brakes was introduced in 2014 we were pleased with their performance in many scenarios. They offered a greater range of adjustability, more positive lever engagement, less noise, less vibration, and more power than the X0 Trail brakes they replaced. This was achieved by using nearly three times more fluid, improving the timing port, redesigning the expanding bladder, adding the "SwingLink" cam to the lever, simplifying various tool-free adjustments, and coming up with a new rotor design. These updates will carry over to the new Ultimates as well.


So what needed improvement on the Guide RSC brakes? While better all around, during long, demanding descents, the amount of lever pull needed to activate the brakes would sometimes change a noticeable amount. There were also ways to better the bleed process. The Guide Ultimates see lots of incremental updates and a new caliper design to address these items.

All-New Caliper


In search of the same lever feel no matter what, the aluminum S4 caliper employs a handful of clever heat management tricks, as well as a redesigned seal and aluminum piston interface. Before you get in a tizzy, know that they're compatible with current SRAM Guide/Avid Trail brake pads.


Heat is a brake's worst enemy, so reducing the amount of heat transferred from the brake pads to the caliper body and fluid was major focus. The first step was to open up the pad pocket for better convective cooling thanks to increased air access. Compared to the Guide RSC (shown on the bottom), the opening on the Ultimate is 2mm wider and quite a bit longer, exposing the full length of the brake pads to air flow.


Next, a heat shield was added. See the aluminum plate near where the back of the pads end? This patent pending addition interrupts the thermal connection between the pad and caliper body, reducing caliper fluid temperature by a whopping 20°C in the most extreme testing conditions. That's pretty substantial.


Finally, the two 14mm and two 16mm pistons per brake are made differently. Previously SRAM used a phenolic plastic for the entire piston. Now the pistons are made from aluminum with a mechanically bonded phenolic pad interface. Why the switch? While phenolic compounds reduce heat transfer well, this particular material was difficult to machine super precisely. Moving to the aluminum piston body with a phenolic insert allowed SRAM to make the piston adhere to tighter tolerances. In combination with new seals, the more consistent finish of the moly-coated aluminum pistons improves piston rollback for a more constant lever feel and contact point while also reducing seal wear.

What doe this all add up to? In the lab, SRAM's own tests determined the constant running temperature of the Guide RSC to be 220°C. Using the same test conditions, the Guide Ultimates came in at 194°C. That's an improvement of 26°C - nearly 12% - which is no small feat. For reference, Shimano brakes run at 193°C (also according to SRAM).

In another lab test SRAM used the brakes at one extreme ambient temperature before quickly heating them up. The Guide Ultimates saw just 4mm of difference at the tip of the lever blade going from -30° to 55°C. The Guide RSC brake had a greater value (less consistency), though SRAM wouldn't confirm exactly how much.

Improved Service


Also new is a revised bleed location and method dubbed "Bleeding Edge Technology." The bleed port is at the bottom of the caliper instead of the middle/top, making it easier to push fluid through the caliper and air bubbles out. The top-down bleed process is simplified thanks to a new lossless adapter tool with a lock-ring and seal. You no longer have to use a little torx key to tighten the port after hose removal, and instead just snap the tool in/out after adjusting the lock-ring. It's quite simple, much cleaner, and much faster than the previous method. The tool will initially come with Guide Ultimate brakes or can be purchased separately for $22.

Guide Lever Updates


Having just undergone a redesign in 2014, the Guide levers remain relatively unchanged, though the new Ultimate model uses a carbon lever blade and titanium hardware. They still have the Swinglink, Timing Port Closure, tool-free Contact Point and Reach Adjust, an aluminum lever body, and lever pivot bearing. And yes, you can swap them from side to side without the need for a re-bleed thanks to the flip flip lever design.

CenterLine X Rotors


Also new are CenterLine X rotors, which are designed to provide the same CenterLine experience from 2014 but with 10-15g weight savings. The two-piece design uses a riveted aluminum alloy center and steel brake track. They come in 140, 160, and 180mm diameters with both 6-bolt and CenterLock hub interfaces. Weights are 86g (140mm), 102g (160mm), and 125g (180mm).

Initial Impressions

While usable in XC to DH scenarios, SRAM says their new brakes are happiest on a Trail/Enduro bike. Ours were paired with dual 180mm rotors and mounted to a Devinci Spartan for a two hour test ride in the luscious hills surrounding Rotorua, New Zealand.


Setup was a breeze, taking just a minute or so to dial in our preferred lever position, reach, and contact point. Back in the X0 Trail days we were always on the far end of most adjustments. With the Guide line we're near the middle, which means the range is truly usable.

Squeezing the Ultimates feels just like the Guide RSC brakes you've grown accustomed to. They're incredibly comfortable with a smooth pull and precise bite point. The lever perch doesn't flex much when really wrenching on the lever, adding to the crisp feel, though the Ultimates are a tad less firm at the lever than the RSC model due to the carbon lever blade. When we rocked the bike back and forth with the brakes locked there was no perceivable play in the pad interface or caliper.

The overall weight savings aren't big, coming in at just 15 grams less than the Guide RSC, but a few grams here and there can add up quickly.


On the trail the brakes had plenty of stopping power to control our 175-pounds of manliness as we wildly careened down unfamiliar terrain. A brake does you no good if it's locked up, and the Ultimates did well as they danced around the edge of traction and maximum power. A good bleed on each of the brakes meant we could really pull on them without a mushy feel. There was no drag the entire ride, no odd vibrations, no chirping, and no turkey warble nonsense. In a blind test, it'd actually be pretty hard to tell a difference between the Guide RSC and Guide Ultimate due to a familiar ride qualities and feel.


While Rotorua does have some challenging technical terrain, the majority of the descents aren't overly steep or long. This meant that we never had the chance to really heat them up. So, for now, the verdict is still out on their performance and consistency on truly demanding terrain. That said, we never once felt a perceivable change in the lever feel or throw during our ride.


As the ride went on we thought less about stopping and more about blasting. In our eyes the best brakes are the ones you don't have to think about, and knowing we could stop on a dime or slow down at the last second allowed us to ride faster and with more abandon, which is precisely what we wanted to do aboard the super capable Devinci Spartan on Rotorua's fun trails. Behind the plethora of acronyms and catch phrases are a pair of brakes that work damn well, and if proven on long steeps the new Guide Ultimates will be winners in our book. We plan to spend more time on them soon.

Visit for more details, and keep an eye out for additional braking developments from SRAM in the near future.

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