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AbsoluteBlack launches wild-looking HollowCage oversized derailleur cage

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AbsoluteBlack HollowCage

AbsolteBlack's all-new HollowCage (Image credit: AbsoluteBlack)
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AbsoluteBlack HollowCage

Its mono-plate design adds flexibility whilst improving performance (Image credit: AbsoluteBlack)
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AbsoluteBlack HollowCage

The plate is dimpled for aerodynamics (Image credit: AbsoluteBlack)
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AbsoluteBlack HollowCage

The large hollow design is the standout design feature, but it's the stiffness of the upper pulley that provides the shifting performance (Image credit: AbsoluteBlack)
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AbsoluteBlack HollowCage

The patent-pending Silent XRing Pulley provides 'almost silent' operation (Image credit: AbsoluteBlack)

AbsoluteBlack has today unveiled the HollowCage, its entry into the market of oversized pulley wheel systems.

A wild-looking concept, the 71-gram HollowCage stands out from conventional designs by virtue of its large hollow centre to the lower pulley wheel, with bold claims surrounding its performance. 

It will go up against products such as Kogel's Kollossos, Muc-Off's L.O.P.S, and Token's Shuriken, as well as the market-leading OSPW from CeramicSpeed. While the hollow design has been done before - by Joshua Ogle of oglecomponentdesign - AbsoluteBlack's HollowCage is the first of the major brands to use this concept. 

It is constructed using a variety of patent-pending designs. The first is a mono-plate carbon cage that eschews the traditional two-sided design in favour of a single plate carbon-polymer that snakes from the left hand side of the upper pulley, downward and outward to finish on the righthand-side of the lower pulley. 

The second comes in the form of a 'Silent XRing Pulley', which AbsoluteBlack claims enables a reduction in noise of 12-14dB when compared to stock Dura-Ace pulleys, thanks to what it calls 'xring rubber suspended bands', that damp the impact between the chain and the teeth of the pulley wheel. 

According to the brand, the HollowCage will now be almost silent in operation, while still maintaining shifting performance on par with Shimano's OEM Dura-Ace. 

To achieve this, AbsoluteBlack claims that it has moved stiffness from the cage to the top pulley wheel, adding tall teeth to the upper pulley to improve shifting accuracy. 

"It’s the upper pulley that moves the chain left and right enabling gear change, so making the upper pulley really stiff allows for greater shifting precision," AbsoluteBlack states. "HollowCage, unlike other pulley cage systems, uses abnormally large, bespoke, full ceramic bearings that make the pulleys incredibly stiff."

To add to this, AbsoluteBlack claims that the mono-plate cage allows flexibility in the cage itself, which allows it to better adapt to chain lines, further enhancing the efficiency of the system. In fact, AbsoluteBlack believes the HollowCage will save more watts overall than any other cage on the market. The monoplate design itself is constructed from a carbon-polymer material, and is covered in dimples to aid with aerodynamics. 

However, it's not the aerodynamics, chain line optimisation or even the ceramic bearing quality where the majority of the HollowCage's performance gains were found. According to AbsoluteBlack, that comes from spring tension. 

"There is a linear correlation between spring tension and the power losses generated by the cage," the company claims. "HollowCage is using lower spring tension than any other cage on the market, while still providing excellent shifting thanks to the unique combination of pulley stiffness and tall teeth profiles."

Unsurprisingly, it's not cheap, launching today with a retail price of £519.00, available at

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Josh Croxton

Josh has been with us as Senior Tech Writer since the summer of 2019 and throughout that time he's covered everything from buyer's guides and deals to the latest tech news and reviews. On the bike, Josh has been riding and racing for over 15 years. He started out racing cross country in his teens back when 26-inch wheels and triple chainsets were still mainstream, but he found favour in road racing in his early 20s, racing at a local and national level for Team Tor 2000. He's always keen to get his hands on the newest tech, and while he enjoys a good long road race, he's much more at home in a local criterium.