Absolute Black claims it has uncovered the reason why cutting material away from disc brake rotors can dramatically alter how well a bike stops.
The brand introduced its first Center Lock rotor, known as the Raven, back in 2012. According to Absolute Black, that 95g rotor drew plenty of interest thanks to its remarkably low weight, and the company kept probing the question of how much material could be stripped from a rotor before braking suffered.
Now, over ten years later, Absolute Black says it has finally cracked the puzzle, and the answer emerged during work on its Graphen brake pads. What first appeared to be routine uneven wear ended up exposing a far deeper principle about how holes should be arranged across a rotor’s friction surface.
Localised hot spots
Absolute Black explains that removing material from the wrong areas of a rotor allows braking performance to fall apart quickly, particularly as temperatures climb. The reasoning is straightforward: less material translates into reduced surface area for soaking up and releasing heat.
When testing the Graphen pads, the company discovered that concentrated overheating stemmed from an uneven spread of material along the height of a rotor’s brake track.
As Absolute Black puts it, a brake pad presses against the whole track. However, when a single narrow circumferential band holds noticeably less steel than the bands right next to it, that zone has less material to absorb and shed the heat produced by friction. The result is that it becomes thermally overwhelmed compared with its neighbours.
This situation can spiral into a damaging cycle. The extreme heat may cause glazing to form on sections of the brake pad, prompting the rider to pull harder on the lever, which only makes matters worse.
Finding the fix
Absolute Black’s answer to this issue is to ensure that every circumferential band running across a braking track contains as close to the same overall length of steel as possible.
That principle guided the design of its newest Raven SL and GT disc brake rotors, which were released on 7 September.
If you chart the quantity of braking material across the rotor’s diameter, Absolute Black argues that the perfect braking surface should stay as flat and horizontal as possible, aside from what it calls unavoidable structural limits.
The company notes that more continuous material is needed around the outer edge of the rotor to maintain structural strength and where the friction track meets the load-bearing arms. Consequently, a graph of braking material would climb at both the narrowest and widest circumferences.
To pull this off, Absolute Black created purpose-built software capable of spotting areas with excessive or insufficient material.
The upshot is that its latest rotors feature numerous small perforations, which create less disruption to that ideal horizontal profile than larger holes would.
The Raven GT reportedly pushes this concept furthest with 500 perforations. Thanks to that design, the GT rotor is positioned for more punishing and extended braking, while the SL opts for fewer, bigger perforations to trim weight. A Raven SL 160mm Center Lock rotor tips the scales at 94g, which is 14g lighter than the equivalent GT.
Absolute Black Raven versus Shimano Dura-Ace
So how does this design philosophy translate into real-world braking? Absolute Black says the German testing facility EFBE Prüftechnik GmbH carried out independent tests on the new Raven rotor alongside a Shimano Dura-Ace rotor for comparison.
In a heat-resistance test, the Absolute Black rotor dissipated 92.7Wh of braking energy, while the Shimano rotor managed 92.9Wh. Absolute Black describes the nearly identical figures as intriguing, given how differently the two brands handle heat.
The company points out that Shimano relies on its Ice Technology concept, whereas the Raven depends on a stainless-steel friction track, a full-floating build, and meticulously tuned perforation geometry.
After bedding in, the Raven paired with Graphen pads produced 241Nm of brake torque at 140N of lever force. The Shimano Dura-Ace setup delivered 211Nm at the same 140N.
That gap suggests the new Absolute Black rotors could bring you to a halt more quickly. However, at £129, they cost twice as much as the Dura-Ace rotors.
