AbsoluteBlack’s new Hollowcage is a one-sided oversized pulley system

Unique looks, big claims and a price tag larger than the lower pulley wheel.

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AbsoluteBlack, the company best known for its oval chainrings and the world’s most expensive drip chain lube, is back with another high-priced product that claims to best its competition. It’s an oversized pulley wheel system with a number of rather neat features that contribute to its US$699 / AU$1,000 asking price. And no, that doesn’t include the derailleur. 

Oversized pulley wheel systems are nothing new and before CeramicSpeed started marketing its OSPW there was Berner with much the same concept. Designed as an aftermarket upgrade for the rear derailleur, the general idea of oversized pulley wheel systems is to reduce the amount of chain articulation through the tight bends of the rear derailleur. Combine that with the low-friction bearings and reduced chain tension and it’s a product that can help retain a marginal amount of power typically lost between the crank and rear wheel. 

However, while the intent is much the same as competing products, AbsoluteBlack’s HollowCage executes on the idea in notably different ways. Do note that we’re yet to try this product ourselves and everything reported below is what AbsoluteBlack has claimed. 

Firstly, the company’s carbon fibre cage design is one-sided, with the pulley wheels contained by lockrings rather than sandwiched between two plates. It no doubt provides a unique aesthetic, and AbsoluteBlack claims that its tests show it to be more aerodynamic than both the stock or competing aftermarket derailleur cages. 

AbsoluteBlack’s design offers a unique aesthetic. The company claims such a design offers functional benefit, too.

Then there’s the hollow lower 18T pulley wheel. We first saw the idea of a hollow pulley wheel from American machining specialists Ogle, and AbsoluteBlack has taken it a step further with its single plate construction that wholly exposes the design. 

While the cage structure and the top 12T pulley wheel are only available in black, the 18T hollow pulley offers a choice of different lockring colours. Both pulley wheels turn on full ceramic bearings that are running a light grease (not oil) which should allow for a little more care-free ownership. 

One of the big pitches from AbsoluteBlack is the HollowCage’s ability to reduce drivetrain noise. The British company claims its cage is as much as 60% quieter than a stock Shimano Dura-Ace pulley system. The trick to this is supposedly suspending the guide pulley (top pulley) on a patented rubber band system that dampens noise. 

Designed for hush are the patent-pending “xring rubber suspended bands.” These can be found around the upper pulley wheel.

Another factor may be the single-side cage design that AbsoluteBlack claims is intentionally more flexible to adapt to varying chain angles. This approach is almost opposite to the common belief that a stiffer derailleur cage shifts better, with the Oval-ring specialists claiming that it’s a stiffer guide pulley wheel with proper-height teeth that provides crisper shifting. 

AbsoluteBlack claims that combining its stiff guide pulley wheel with tall teeth profiling produces the best-shifting oversized pulley wheel system on the market. The company goes as far as to claim that shift quality is matched to the stock Shimano cage. Of course, this is all coming from the company that produces Oval chainrings that almost all mechanics around the world will agree offer a significant downgrade in shift quality. 

Interestingly, AbsoluteBlack doesn’t make much of a deal about the oversized pulley wheels or ceramic bearings (probably because all of its direct competitors already do this). Rather the brand states that much of the frictional savings come from the derailleur cage tension on the lower span of the chain, and the ability of the cage to adapt to the chainline (something that single-sided cage is claimed to do). 

Full ceramic bearings are used within the pulley wheels, not that the company makes a big deal of it.

The original FrictionFacts (now owned by CeramicSpeed) white paper on oversized pulley wheels was first to note such frictional benefits of lower spring tension. However, that white paper also mentions that tall and square tooth profiles can increase friction at the lower pulley wheel when cross-chaining. AbsoluteBlack’s concept seems to claim that its intended cage flex overcomes this potential issue. Unfortunately, there aren’t any independent labs currently set up to dispel or prove such a claim. 

The company also claims its competitors require higher spring tension to maintain reasonable shift quality, while it is able to reduce this tension without such an impact. What the company fails to discuss is that often spring tension assists chain retention on poorly surfaced roads – too little tension could result in your chain having a floppy fight with your carbon chainstay (something I mentioned in my review of CeramicSpeed’s OSPW). Thankfully like CeramicSpeed’s OSPW, AbsoluteBlack’s design does offer three spring tension settings so you won’t likely be forced to hear your chain bounce around for the sake of saving an unmeasurable watt. 

Currently, AbsoluteBlack only offers the Hollowcage to suit Shimano R9100-series and R8000-series rear derailleurs in either mechanical or electronic configurations. This offers up to an 11-32T cassette capacity. There are other cage fitments in the works but we don’t have concrete information on what they’ll be or when we’ll see them. The cage assembly is claimed to weigh 71 grams, pretty similar to a CeramicSpeed OSPW and approximately 20 g heavier than a stock Shimano Dura-Ace cage.

Overall the new Hollowcage offers a unique take on an existing idea that has been proven to offer marginal gains when all the right elements align. Of course, such an intricate design comes with an absolutely eye-watering price that makes some other expensive oversized pulley wheels systems look like low-cost bargains. I guess the saying ‘it pays to be different’ applies here. 

More information can be found at absoluteblack.cc.

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