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


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

Oversized pulley systems aren’t new and before CeramicSpeed ​​started marketing their OSPW there was Berner with much the same concept. Designed as an aftermarket upgrade for the rear derailleur, the general idea of ​​oversized pulley systems is to reduce the amount of chain articulation through tight turns of the rear derailleur. Combine that with the low friction bearings and reduced chain tension and it’s a product that can help keep a marginal amount of power typically lost between the crank and the rear wheel.

However, while the intent is roughly the same as competing products, AbsoluteBlack’s HollowCage executes the idea in different ways. Note that we have not yet tried this product ourselves and everything reported below is what AbsoluteBlack has claimed.

First, the company’s carbon fiber cage design is one-sided, with the pulley wheels contained by locking rings rather than sandwiched between two plates. It undoubtedly offers a unique aesthetic, and AbsoluteBlack says its tests show it to be more aerodynamic than stock or competitive aftermarket derailleur cages.

The design of AbsoluteBlack offers a unique aesthetic. The company claims that such a design also offers functional advantages.

Then there is the 18T hollow bottom pulley wheel. We first saw the idea for a hollow pulley from US machining specialist Ogle, and AbsoluteBlack took it one step further with its single plate construction that fully exposes the design.

While the cage structure and 12T top pulley are only available in black, the 18T hollow pulley offers a choice of different locking ring colors. Both pulley wheels run on full ceramic bearings that run on a light grease (no oil), which should allow for a bit more worry-free use.

One of AbsoluteBlack’s big selling points is the HollowCage’s ability to reduce driveline noise. The British company claims its cage is up to 60% quieter than an original Shimano Dura-Ace pulley system. The trick is to hang the guide pulley (upper pulley) on a patented elastic system that reduces noise.

Designed for silence, the patent-pending “xring rubber hanging bands”. These can be found around the top pulley wheel.

Another factor may be the one-sided cage design which AbsoluteBlack says is intentionally more flexible to accommodate different chain angles. This approach is almost opposed to the common belief that a stiffer derailleur cage shifts better, with oval bush specialists claiming that it is a stiffer guide pulley wheel with teeth at the proper height. which allows for a sharper shifting.

AbsoluteBlack claims that the combination of its rigid guide pulley wheel with a high tooth profile produces the most changeable oversized pulley system on the market. The company goes so far as to claim that the quality of the gear changes is matched to the original Shimano cage. Of course, this all comes from the company that produces oval chainrings that almost every mechanic around the world will agree to offer a significant degradation in the quality of the gear changes.

Interestingly, AbsoluteBlack doesn’t make much of oversized pulley wheels or ceramic bearings (probably because all of its direct competitors already do). Rather, the brand claims that a large portion of the friction savings come from the tension of the derailleur cage on the lower end of the chain and the cage’s ability to adapt to the chain line (which this cage to one side is supposed to do).

Full ceramic bearings are used in 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 the first to note these friction benefits of lower spring tension. However, this white paper also mentions that tall, 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 problem. Unfortunately, no independent laboratory is currently set up to dispel or prove such a claim.

The company also claims that its competitors need higher spring tension to maintain reasonable shifting quality, while still being able to reduce that tension without such an impact. What the company fails to discuss is that spring tension often helps hold the chain on poorly paved roads – too little tension could cause your chain to struggle with your carbon chainstay (something I do). mentioned in my OSPW review of CeramicSpeed). Fortunately, like CeramicSpeed’s OSPW, AbsoluteBlack’s design offers three spring tension settings, so you probably won’t have to hear your string bounce to save an unmeasurable watt.

Currently AbsoluteBlack only offers the Hollowcage to fit Shimano R9100 and R8000 series rear derailleurs in either mechanical or electronic configurations. This offers a cassette capacity of up to 11-32T. There are other cage improvements underway but we don’t have concrete information on what they will be or when we will see them. The cage assembly is said to weigh 71 grams, quite similar to an OSPW CeramicSpeed ​​and about 20g heavier than an original Shimano Dura-Ace cage.

Overall, the new Hollowcage offers a unique take on an existing idea that has proven to deliver marginal gains when all the right elements align. Of course, with such a complex design comes an absolutely mind-blowing price tag that makes other expensive oversized pulley systems look like cheap bargains. I guess the saying “it pays to be different” applies here.

More information can be found at Absoluteblack.cc.

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