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AbsoluteBlack today unveiled the HollowCage, its entry into the oversized pulley systems market.
A wild-looking concept, the 71-gram HollowCage sets itself apart from conventional designs due to its large, hollow center all the way to the lower pulley wheel, with bold claims surrounding its performance.
It will take on products such as Kollossos from Kogel, LOPS from Muc-Off and Shuriken from Token, as well as the market leader OSPW from CeramicSpeed. While the hollow design has already been done – by Joshua Ogle of oglecomponentdesign – AbsoluteBlack’s HollowCage is the first of the big brands to use this concept.
It is built using a variety of patent pending designs. The first is a single-plate carbon cage that eschews the traditional two-sided design in favor of a single carbon-polymer plate that winds from the left side of the top pulley, down and out to finish on the right side of the lower pulley.
The second comes in the form of an “XRing silent pulley,” which AbsoluteBlack claims provides 12-14dB noise reduction compared to the stock Dura-Ace pulleys, thanks to what it calls “Xring rubber suspended bands”, which absorb the shock between the chain and the teeth of the pulley.
According to the brand, the HollowCage will now be nearly silent in operation, while maintaining shifting performance comparable to that of Shimano’s Dura-Ace OEM.
To achieve this, AbsoluteBlack claims to have shifted the stiffness of the cage to the upper pulley wheel, adding tall teeth to the upper pulley to improve the precision of gear changes.
“It’s the top pulley that moves the chain to the left and right, which allows the shifting, so making the top pulley really stiff allows for greater precision in shifting,” says AbsoluteBlack. “HollowCage, unlike other pulley cage systems, uses unusually large custom all-ceramic bearings which make the pulleys incredibly stiff.”
To add to this, AbsoluteBlack claims that the single-plate cage allows flexibility in the cage itself, allowing it to better adapt to chain lines, further improving the efficiency of the system. In fact, AbsoluteBlack believes the HollowCage will save more watts overall than any other cage on the market. The single-plate design itself is constructed from a carbon-polymer material and is covered with dimples to aid aerodynamics.
However, it’s not the aerodynamics, chainline optimization, or even the quality of the ceramic bearings where the majority of the HollowCage’s performance gains have been found. According to AbsoluteBlack, it comes from the spring tension.
“There is a linear correlation between spring tension and the power losses generated by the cage,” the company says. “HollowCage uses lower spring tension than any other cage on the market, while providing excellent shifting thanks to the unique combination of pulley stiffness and high tooth profiles.”
Unsurprisingly, it’s not cheap, launched today with a retail price of £ 519.00, available on AbsoluteBlack.cc.
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