Direct mount RD hanger. Various models available here. I'm not sponsored/affiliated.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Thx for the data. Didn’t think the split would be so even.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Not buying the Cervelo one, if it can't open a beer bottle

So... I need to update my review after my second ride. Whether this second review is similarly worthless or not - you can decide.

TLDR: On second ride (first one at more than recovery/coffee pace), chain derailed from the bottom pulley wheel while in large group at high speed. I'm skeptical of the Hollowcage design, and have already pulled if from my bike and put the Ceramicspeed OSPW back in its place.

First Ride OK: My first ride with the Hollowcage was on August 26. A very easy (145W NP) 22.61 mile ride (Strava link here). No issues.

Second Ride not OK: Next ride with the Hollowcage was on September 4 (Strava link here) and was intended to be a fast group ride. While riding in a large group on PCH in Los Angeles, my drivetain seized up. I looked down and the chain was hanging like a chain drop. But my chain remained on the big ring. Once I was able to come to a stop, I could see that the chain had derailed off the lower pulley wheel:



In case you are asking yourself, wait a second, you didn't ride the Hollowcage between Aug 26 and Sep 4, that's correct - between the 2 rides on the SystemSix/Hollowcage, I did 4 rides on my EVO Disc and 2 Zwift rides on the KICKR Bike. If any ST investigators would like the .FIT files for these rides, I am happy to provide them.

As you can see from the photo above, the small "retaining tab" was intact. In order to limp home, I sat on the side of the road until I was finally able to shove the chain past the retaining tab and back onto the lower jockey wheel. In the process, I broke the tab:



Absolute Black Response: I emailed AB with my experience, contrasting my tens of thousands of miles on Ceramicspeed OSPWs over multiple bikes and never having this issue with the 36 miles it took for the Hollowcage to fail. I requested a refund, noting that I was not comfortable riding or selling the Hollowcage to a fellow rider. Absolute Black responded that no refund would be issued, as the Hollowcage was used, and instead sent me a replacement cage just a couple days later. Whether that's unacceptable or fantastic customer service - I'll let you decide. From my perspective, I have a $699 product that is not suitable for riding, at least not until I'm confident my experience was not a freak incident and not indicative of a design flaw.

Design Flaw?: The Hollowcage certainly looks cool, but does it do so at the expense of functionality? I don't know the answer, but given my experience, I think it's a fair question. Compare a stock Dura-Ace derailleur cage with the Hollowcage and a Ceramicspeed OSPW:



When pedaling, the chain contacts the lower pulley wheel where indicated with the blue arrow, before it makes its way through the pulleys to the cassette. The DA and Ceramicspeed cages (and every other RD cage) have extended "guides" that surround the chain to keep it on the lower pulley. Critically (IMO) with a "typical" RD cage, the guide extends to where the chain first meets the lower pulley. The Hollowcage, on the other hand, has no such "guide" (well other than the small tab but even that is not positioned where the chain meets the lower pulley) and so if for whatever reason tension is lost and the chain hops off the lower part of the lower pulley, it's going to derail. That's my theory anyways, based on my admittedly n=1 experience.

I'll be curious to see if others have a similar experience. I hope not, but I can't help but think it's likely that Absolute Black will need to redesign the cage to include a more traditional lower pulley "guide" for the chain.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

i really appreciate this review.

at the pricepoint for this sort of item, this thing should be flawless. there should be no possibility of a consumer having this sort of problem.

the thing looks like it belongs on a tron bike, ill give it that though.

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80/20 Endurance Ambassador

I know you’re just a hobbiest cyclist - but this feels like a super damning review

I was debating buying one, just because it looks different, but this review makes me simply not want to buy.

I'm just relaying my admittedly brief but unsuccessful history with the Hollowcage. I hope my experience is an outlier, but given the design of the cage, I suspect it may not be.

I run 1x on my TT bike. I first ran just a narrow/wide chainring, then later added the Aerocoach chain guide (both helped), but it wasn't until I switched to a clutched rear derailleur (first the Ultegra RX-805 and now Red AXS) that I was able to eliminate chain drops (and the chain guide was no longer needed).

The Hollowcage is relying on the narrow/wide teeth of the lower pulley wheel (and I would think, cage tension) for chain retention, but critically (IMO) not a clutched RD. My sense is that the current design might work just fine with a clutched RD, and might well eliminate the chain derailment I experienced, just as a clutched RD eliminated chain drops on my 1x TT bike. But the Hollowcage is currently available only for Dura-Ace 9100/8000 RDs, which are non-clutch RDs.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

That extra large diameter bearing design is not what an engineer who is concerned at all about friction would use....

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

If oversized pulleys actually worked then Shimano, SRAM and Campagnolo would have them as standard. They don't.

That's not at all how it works. There are lots of ways manufacturers could make their products but don’t, and there are dozens of valid reasons for that. There is no need for Shimano to increase their mfg cost if it won't mean extra sales. And I bet no one is choosing groupsets based on pulley wheels.

Go with an SLF Motion system. It’s definitely cheaper than that Absolute Black system, there’s two different SLF systems available right now, and I’m sure if you “traded in” that AB system you would get some sort of discount or credit.. I’m willing to bet it’s much more durable than Ceramic Speed, too!

https://slfmotion.com/...ons/evo-speed-system

I recently went with a Nova Ride OSPW, which is French made and has sealed full ceramic bearings (so both races and balls) for a fairly reasonable price, a bit under 250 Euro.

that depends on your definition of "work" - they do work to reduce frictional losses, to some debatable amount.
the reason why they're not standard is that they do not work as well to provide smooth reliable shifting which is what the mainstream manufacturers (especially shimano) prioritise, since that is what most consumers prioritise.

'Reasonable price'..when compared to the 'are you on drugs, drunk, been hit on the head, totally crazy, pulling my leg, have to be kidding me, no offing way' price of the Ceramic speed OSPW....

Hi @refthimos it's absoluteBLACK here.
We just wanted to clarify a few things for the rest of the forum members. As per our response to your email, the pictures of your bike which you sent us (before the damage to our cage) make it immediately obvious that the chain length and the B gap adjustment to the cassette sprocket on your bike were completely incorrect. Those are main factors that caused the chain drop from lower pulley and then subsequent damage to the part of the cage while you were trying to insert the chain back on the lower pulley without opening the chain. Too long chain in any ospw will cause trouble as the cage is not at the proper tension.
Moreover, you are using an aftermarket DM hanger which further increases the risk of issues with the rear derailleur

We have also came across an Instagram profile of @refthimos which we assume belongs to you (the actual name and location checks out also ) The post from 25th of July 2020 is showing a snapped Ceramic Speed OSPW cage in half, which you told us, you never had any problems with. Judging by the way it snapped and the chain position, it was pulled into the back wheel which, in most cases, is a result of incorrect RD adjustment and too long chain.



Regardless of all the above, and the fact that this was installation/user error, we have immediately sent you a replacement MonoCage, FREE of charge so you can continue using our HOLLOWcage.

I hope this clarifies a bit better the situation. We have extensively tested our product for over two years including riding on the cobble stones. Yes, the design is nothing you have seen before but we made sure it works providing the correct setup which we detailed on our website. We understand you may be upset that this happened on the second ride but no matter how we look at it, it was incorrectly mounted and this was the result of it.

I certainly hope this clears things up. It was generous that you provide a new one.

This must be the 'Comeback of the Year' :)

Uh oh...Need to continue checking this thread.

Hahahah I love this place

TLDR: If you provide an installation video that does not tell the consumer that "incorrect" chain length is critical/can cause a problem, while at the same time telling the consumer that their chain length should be fine if swapping from another OSPW, then it's hard to blame the consumer for an "incorrect" chain length that works just fine with their existing rear derailleur/cage.

Absolute Black's Installation Video: Here is the video that you provide to customers entitled "How to Mount absoluteBLACK HOLLOWcage"

https://www.youtube.com/...zIRvvcvNr4s&t=4s

Here is what you say about chain length in the installation video:

"Keep in mind if you're swapping from a short cage of Shimano Dura-Ace or Shimano Ultegra cage, in those cases you will most likely have to extend the chain for two to three links for the optimal performance. If you're swapping from a long cage or from any other brands that are using oversized pulley wheels, in those cases the chain length normally remains the same."

That's everything on chain length. Based on your own video, it seems reasonable that a consumer would conclude that the same chain length that works well with the Ceramicspeed OSPW will work with the Hollowcage.

I now see that there is a separate video on your website re: chain length. I don't recall seeing that before - was that added or was it always there? In any case, I was not aware of that video, and if chain length is so critical (apparently, rather unique to the Hollowcage, since we'll contrast my experience with Ceramicspeed in just a bit), why doesn't the installation video make any mention of this? If you're going to provide an installation video, at a minimum you need to tell consumers that they need to also find and watch your second video regarding chain length. Though as a friendly suggestion (again, if chain length is so critical), I think combining the two videos (so that consumers need only watch one installation video) would be best.

From a consumer perspective, I don't think it's unreasonable that, after watching the official Absolute Black installation video, the consumer can conclude they've been told everything they need to know to install the product correctly.

Hollowcage More Sensitive to Chain Length: Let's go ahead and stipulate that my chain length was longer than what you demonstrate in your second video (BTW your main installation video shows up on YouTube but for whatever reason the second chain length video does not). [EDIT: See post below, and this video; as it turns out, the chain length was fine (at least according to AB's own video on the subject) /EDIT]. That tells me that the Hollowcage is much more "sensitive" to chain length than a stock RD cage or a Ceramicspeed OSPW. I ordered my first two Ceramicspeed OSPWs in Dec 2015 and have had them on all my bikes (road and TT) since then. As of today, I have a little over 50,000 miles on the Ceramicspeed OSPW, without encountering the chain derailing from the lower pulley wheel. But it took 36 miles for this to happen with the Hollowcage. This to me underscores that if chain length is really that critical with the Hollowcage, you should ensure consumers are aware of that fact.

Instagram Post: As far as the Instagram post you dug up, while I applaud the ST Sleuthing involved, that was a 9000 series DA RD, which as I'm sure you know features a completely different design from the 9100 series DA RD. I worked with Ceramicspeed to diagnose the cause of that failure, and it had nothing to do with chain length - in fact at no time did Ceramicspeed even inquire about my chain length. Everything was resolved without any drama or issues, as evidenced by the fact that I continue to use their product.

Yes, I Broke the Retaining Tab: I try to be pretty upfront about product failures, including my role in them. I noted that the retaining tab only broke after I had to force the chain back into the cage to limp home (I don't carry a chain tool with me, as I don't think I've broken a chain while riding in at least the last 10 years). I blew up an Enve wheel and posted about it here on Slowtwitch, volunteering that I did not use Enve tubeless tape but instead Silca tape. Since that incident, Enve modified its website to require the use of its tape and even introduced a new product - their Pressure Relief Valve Stem Nut - to protect against similar failures. When I cracked a Knot 64 rim on the same SystemSix used with the Hollowcage, I didn't submit a warranty claim or anything like that, instead I provided my LBS and Cannondale a slowmo video showing the big piece of metal that caused the failure. In other words, I'm not a "JRA" type unless, well, I really was JRA.

An Honest Question Re: the Retaining Tab: While I'm not an engineer or component designer, why is the retaining tab placed where it is (i.e. more or less in the middle of the contact area between the lower pulley and the chain?) Wouldn't placing it closer to where the chain contacts the lower pulley be better for retaining contact between the chain and the lower pulley wheel? Since the retaining tab is so small (compared to the retaining "sub cage" found on every other RD cage) presumably you believe the the narrow/wide lower pulley wheels and RD cage tension are sufficient to keep the chain from derailing, but in that case, why even include the retaining tab? It seems that you either need a retaining tab/sub-cage or you don't, and so I would expect to either see that piece moved closer to the initial contact point or removed entirely.

Another Honest Question re: Direct Mount Hanger: What is it about a direct mount hanger that will cause issues with the Hollowcage? I see nothing on your website or videos mentioning direct mount hangers. If the Hollowcage is incompatible with direct mount hangers or if there is something the consumer should do differently with a direct mount hanger, you should make this known.

Avoiding Future Failures: I hope you consider my suggestion to modify your installation video to include whatever instructions are needed regarding chain length, so that the consumer is aware of this requirement. If everyone purchasing the Hollowcage is made aware of that requirement and if chain length does indeed resolve chain retention, I will be more than happy, as that will allow me to pass along my Hollowcage to another rider - and in the end, as a cycling enthusiast, I want bike companies and their products to succeed rather than fail. For now though, I think for me it's best to wait and see while the Hollowcage remains in a parts box.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Sure that is assuming you had the chain length and b-screw correct the first time, which based on insta wasn’t the case.

Furthermore, they didn’t say should be fine, they said normally stays the same. Not the same thing. That doesn’t mean you say f it and keep it the same length cause it’s normally the same. You go in with the assumption that it probably won’t need to change it you measure the same way you’re supposed to validate.

No where does it say yeah you’ll be good just move it over with the same chain length.

He did say he had his mechanic install it. So, the question is did he make sure the mechanic would take care to properly understand how to install this part for likely the first time. But that also means the mechanic is the one who left it with an improperly setup B screw. So, maybe he should be looking for a new mechanic?

Grantbot21 wrote:

Sure that is assuming you had the chain length and b-screw correct the first time, which based on insta wasn’t the case.

Just to be clear, you can tell from the Instagram photo that the chain length and b-screw weren't correct? As I noted, Ceramicspeed did not raise this as a concern.



The video says "the chain length normally remains the same" with no further commentary. What is the consumer supposed to do, guess all the scenarios in which normally doesn't apply? Is it really radical to suggest that if chain length is so critical, the installation video would instruct the consumer as to what chain length is required?

Since you've assumed you know my chain length was incorrect, I went ahead and pulled up the Absolute Black chain length video (I can't link directly to the video, but it's all the way at the bottom of the product webpage). It says to put the chain in the little chainring and the 3rd smallest cog (basically, as far down as Di2 will let you shift while in the small ring). On my bike, that's the 36/13 combo. It then says to set the chain length to where the chain "just becomes under tension." Well, here is my bike, same chain that derailed with the Hollowcage, in the 36/13 combo. As you can see, the chain is under tension. So it complies with the Absolute Black chain tension video. Which, I'll note again, is not even mentioned in the installation video.

https://vimeo.com/612890966

One other note: While Absolute Black recommends the lowest spring tension setting for my 52/36 11-28 drivetrain to minimize drivetrain loss, my mechanic is relatively conservative and since I use one of the two middle tension settings with the Ceramispeed OSPW, he used the middle tension setting on the Hollowcage. So it was installed with more spring tension than needed.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Basically they took a ceramic bearing, made some teeth, and attached the teeth to the bearing itself. So what your buying is really just a ceramic bearing for a lot of extra money.

Back at you................

https://www.youtube.com/watch?v=E7VxFaLqC_g