AbsoluteBlack HollowCage reimagines wild, low friction rear derailleur pulleys

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Everyone and their brother has tried to make drivetrains faster with larger derailleur pulleys & ceramic bearings, but absoluteBLACK’s new HOLLOWcage may be a truly revolutionary bike upgrade. The name pretty much sums it up, your conventional cage & pulleys get replaced by a lightweight hollow carbon cage with a giant low friction carbon pulley ring that spins on smooth ceramic bearings, and is quieter than ever…

absoluteBLACK carbon-ceramic HOLLOWcage low friction upgrade

Absolute Black carbon-ceramic Hollow Cage low friction upgrade, PVD rainbow

From the birth of the modern derailleur, the two-plate cage sandwiching two spinning pulleys to maintain chain tension has remained virtually unchanged. Ceramic bearings made the derailleurs faster-spinning and plenty of oversized pulley wheel systems have reduced drivetrain friction overall.

But now, Absolute Black promise next-gen performance upgrades with their new carbon-ceramic HollowCage system. The single-sided derailleur cage upgrade is said to deliver faster shifting, silent-running, improved aerodynamics, and the smoothest-rolling low-friction ceramic bearings on the market.

Absolute Black claims “super silent” operation, shifting “as good as” stock Dura-Ace cages, improved aerodynamics, and “more watt-savings” than any other cage available!

Tech details – What’s new?

Absolute Black carbon-ceramic Hollow Cage low friction upgrade
all images c. absoluteBLACK

Obviously, everything here is new, so let’s look at the details that make it work. The “mono-plate” cage itself is made of “carbon-polymer” material, which sounds like the same high-performance carbon-reinforced composites we’ve seen from stiff shoe soles to Italian derailleur components. It also gets a dimpled surface à la Zipp for improved aerodynamics. But Absolute Black says that a bit of flexibility in the cage is the secret here allowing the upper pulley to be perfectly placed for precise shift actuation while the lower pulley can more accurately twist to align towards the chainring for reduced friction

Absolute Black carbon-ceramic Hollow Cage low friction upgrade, angled details

The custom pulleys are also made of carbon-polymer, with the more-conventional closed & stiffer 12T upper guide pulley spinning on an oversized ceramic bearing, but still only attached from one side. The wild-looking, open 18T lower pulley is carbon-polymer again, this time spinning between two custom oversized ceramic bearings, held in place by a custom, scalloped lockring.

Absolute Black carbon-ceramic Hollow Cage low friction upgrade, backside inside

Absolute Black says their patent-pending “Silent Xring Pulley” system ensures quieter engagement of the chain to the tall teeth of their pulley, improving the already quieter operation of composite pulleys vs. alloy. Compared to stock Dura-Ace pulleys, they say these “reduce the sound level by 12-14dB” for roughly 60% reduction of pulley noise. The secret they say is the rubber Xring element inside the upper pulley that damps the impact of the chain to the guide pulley’s teeth, which they say was “the single biggest contributor to overall drivetrain noise”.

Absolute Black carbon-ceramic Hollow Cage low friction upgrade, Xring silent detail

Those tall teeth are also said to allow lower spring tension than any other cage on the market, without compromising shift precision. That means lower system friction and more watts-saved, still providing excellent shifting thanks to the unique combination of pulley stiffness and tall teeth profiles. In addition, it is the only cage that can dynamically adapt to the variable chainline, minimizing friction at the lower pulley.

absoluteBLACK HOLLOWcage – Pricing, availability & options

Absolute Black carbon-ceramic Hollow Cage low friction upgrade, colors

The new absoluteBLACK carbon-ceramic HOLLOWcage derailleur upgrade is said to weigh just 71g, and sells for an eye-watering $700 / 600€ / £520. On top of the standard matte black composite of the pulleys & cage, it comes in five different anodized finishes for the lower pulley lockring – black, gold, red, titanium & PVD rainbow.

Absolute Black carbon-ceramic Hollow Cage low friction upgrade< dura-Ace upgrade

The new HollowCage is currently compatible with Shimano Dura-Ace R9100/R9150 & Ultegra R8000/R8050 series rear derailleurs, and with up to 32T cassettes.


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