SRAM's recently launched Guide brakes have been well received, possessing performance and reliability that are a marked improvement from the previous Elixir line. By ditching their TaperBore master cylinder and going with a cam activated cup seal and port system, SRAM was able to create a brake that has earned praise for its excellent modulation and lever feel. Now, just over a year after the Guide brakes were first announced, SRAM has a new addition to the line, the Guide Ultimate.
The Guide Ultimate's lever body internals are the same as on the standard Guide but the blade is made of carbon fiber, and titanium hardware is used for further weight savings. The use of carbon and Ti isn't the real story though – it's the new caliper, which received a complete overhaul as part of SRAM's goal to develop a brake with an extremely high level of consistency, one that maintained the same lever feel throughout a run, no matter how long or steep the trail.
Guide Ultimate Brake Details
• Intended use: all-mountain / trail
• New S4 four piston caliper
• Heat shield in caliper for reduced fluid temperature
• Titanium lever hardware
• Increased pad pocket
• Uses same pad shape as standard Guide and Trail brakes
• Weight: 360 grams (front brake, includes rotor, hose, clamp, adapter and all bolts)
• MSRP: $288 USD per wheel
• Available May 2015
To help achieve their goal of creating a brake with even better consistency, SRAM uses four aluminum pistons in each caliper. This reduces the likelihood that a misaligned piston will apply uneven pressure to a brake pad, and helps reduce seal wear. Instead of being completely machined from aluminum, there's an insulator in the center of each piston to help dissipate heat, while the surface of each piston is also covered with tiny grooves that are meant to help improve rollback, the speed that they return to their original position after the lever is released. Improved Heat Management:
Excessive heat buildup is the enemy of disc brakes, and companies go to great lengths to try and keep temperatures in check for as long as possible. To that end, SRAM has come up with a simple yet supposedly very effective heat sink that is located just in front of the brake pads. The horseshoe shaped piece of stainless steel channels heat away from the pads, and SRAM's in-house testing found that this created a 20°C reduction in running temperature. The shape of the caliper itself has been altered as well – the pad pocket (the portion of the caliper where the pads sit) has been widened in order to increase the amount of airflow between the rotor and the pads for additional cooling. New Rotors:
The Guide Ultimates come with new Centerline X rotors that are up to 20 grams lighter than the standard Centerline rotors. The use of a two piece design is the reason for this weight reduction, with the seven arms of the rotor mounted to an internal carrier. Two piece designs can occasionally develop play over time, leading to an annoying 'kathunk' that feels like a loose headset when the brakes are applied, but SRAM say that they took special care when designing the interface between the outer and inner portion of the rotor to keep this from happening.Simplified Bleeding Procedure:
It's fair to say that nearly anyone who's ever bled a set of brakes has one time or another dropped a miniscule bleed screw and watched it immediately roll under a bench, an event that's usually followed by a good amount of cursing and maybe some hair pulling. To help prevent temper tantrums, SRAM has developed a trick new bleed adaptor that should make brake maintenance much easier. The adaptor pushes into a port on the caliper, and then the anodized knob is back off slightly, allowing fluid to be pushed from the syringe through the caliper to the lever. Bleeding the Guide Ultimates is extremely simple, and requires fewer steps than what was required for any of SRAM's previous brakes. The new adaptor will be included with every Guide Ultimate brake set.
|I was able to get out for a short ride on the new Guide Ultimates, but as fun as the rolling, berm filled trails of Rotorua were, there wasn't enough sustained braking to determine whether or not the new features make a difference in the consistency department. They did work well throughout the entire ride, with the excellent balance of power and modulation that the Guide brakes have become known for, but there wasn't a noticeable difference in lever feel or performance from the standard version. That's certainly not a bad thing, and once they're available we'll get a set in for review, at which time I'll be able to take them on steeper trails with enough vertical to give them a proper evaluation, including giving the simplified bleed procedure a try. - Mike Kazimer |