The oversized cassette hacks brigade just keeps on rolling, this time with a unique entry from Absolute Black.

Rather than replace just the single top cog, AB’s offering adds a 40t large cog onto a single piece of machined aluminum containing your 28, 32 and 36 cogs, too. Founder Marcin says the benefits are three-fold. First, it’s a stiffer unit as a cluster, so shifting should be very precise. Second, there’s more surface contact area on the freehub body, so less likely to dig into it and get stuck.

Third, it’ll weigh a lot less. How much so? Shift down and see…


The cluster has a solid platform sitting on the freehub body, making a wide 15mm connection rather than a typical ~4mm patch. The rest of it looks blocky and solid from the front…


…but the back tells a different story. Marcin says it’s been in the works for a year and has been much more difficult to produce than originally thought.

Like the others, it requires the removal of one cog. Normally, that’s either the 15t or 17t. Or, you can get their 13t lock ring and remove the 11t to shift the entire range to an easier spectrum without creating any huge jumps between gears.


Compared to a single cog upgrade, which they say adds about 50g to a cassette, Absolute Black’s cluster can reduce the total weight by as much as 52g, making the total apples-to-apples weight savings in the ballpark of 100g. Chart above provided by AB.

Weight savings are good. Money savings are equally enticing, and this unit retails for just $122…pretty competitive for the segment considering the extra work that goes into it. And that it’ll save wear and tear on some of the more heavily used parts of your cassette.


It’s compatible with SLX and XT 11-34 and 11-36 cassettes. In most cases, he says it should only require a few turns of the rear derailleur’s B-screw to make it all work.

These photos are of a late stage pre-production piece. Final parts will be all black, and they’ll start shipping April 26th. Preorders are open on their website here, and the first 100 orders get the 13t lock ring included free. That part should be available separately soon, too.


In other news, they’ve updated their direct-mount SRAM single chainrings to a narrow-wide tooth profile. They’ve been using it on their Shimano-XX1 and CX rings, so moving forward all will have that new tooth design.

Unfortunately, all his success with the chainrings (and, likely, this item) has put the other killer goods like those prototype pedals and beautiful disc brake rotors on hold. But, we’re excited to see a small brand grow!



  1. Ham-planet on

    Taking off the 11t to fit an ultra low-end cog(s) defeats the entire purpose: that’s less range than an 11-34 cassette. If you just need a lower gear, fit smaller chainrings.

  2. groghunter on

    not so sure about running everything down to the 28t in aluminum… A 40t or 42t may not get that much wear, but when you get down to 28t, I’m probably up in that quite a bit more.

  3. James S on

    If you use a cassette with 11-36 with a 28 tooth chainring (need to go with a one-piece chainring like the MRP Bling Ring to get one in that size) then your low ratio is 0.78 and your high ratio is 2.55. Compare that to the 0.8 and 2.46 you would get if you used this Absolute Black adaptor and 13 tooth lockring with a 32 tooth chainring. (Just like Ham-planet said – you lose range. Not much, but it still doesn’t make any sense).

    I think the price is fairly reasonable given the machining, but it was pretty silly to bother with the 13 tooth lockring.

  4. MountainBikeMike on

    Might want to run this stuff through copy editing/proof reading prior to publication. The headline is wrong. There is no 42-tooth option. There is a 40-tooth option. The body copy got it wright. The headline is wrong.

  5. Tyler Benedict on

    Keep in mind, some people don’t want to change anything up front and are just looking for the cheapest, easiest way to make it easier to get up hill before they bomb down it. For those folks, the 13t lock ring makes sense. For everyone else, they can just remove the 15t or 17t. Or both, and use the OneUp 16t we just posted.

  6. absoluteblack on

    Marcin here from Ab.

    Just to make it clear, you don’t have to take 11T out if you don’t want to. You can just take one of 15 or 17T like you would do with fitting just one 40/42T single cog.

    Reason we did the 13T special lockring is the study which showed us that most people actually do not use 11T on the trail. This was a bit surprising but true.
    All you can read here or on forums is the range and calculations. But in real world many, many riders just use 13T upwards:)
    Of course there are people who use one bike to “do all”, racers, CX riders and so on who do need 11T. We found many enduro and trail riders don’t use it, so here is just another option you can use.

    Regards lowering front ring tooth count. Sure this does a trick. But what if you are already on 32, 30 or 28T? Not much option to go more down at the front. Besides some people don’t like very small cog at the front from few reasons…

  7. MountainBikeMike on

    Next fix: The permalink. absolute-black-unveils-4-cog-42-tooth-oversized-cassette-adapter/ should read: absolute-black-unveils-4-cog-40-tooth-oversized-cassette-adapter/.
    It’s always love. — Avon Barksdale

  8. Carder on

    With the effort that went into this why no deduct the ring that has to be removed out of the low rang gears. That way the factory cassett could be ran unchanged.

  9. absoluteblack on

    Forgot to mention that it also fits to Sram 1050 cassettes!:)
    Same procedure as to XT. You have to take last cluster + one cog. But you can’t take off 11T in this case as it will result improper build.

  10. gerald t. on

    So, all you guys tooling up for kludgey half cassettes know that when x9-1 is released you’re gonna eat that investment, right?

  11. gerald t. on

    Also, second the notion about dropping the 11t being stupid. It’s really shocking how many people don’t understand that going to a smaller chainring accomplishes the same thing.

  12. goridebikes on

    It’s also worth noting while you know-it-alls are arguing about changing chainrings instead, that the 2t jump in the cassette represents substantially more change than an equal change in chainring size.

    To wit, James S: a 13x32t is nearly equal to an 11x28t, and a 32×28 is equal to a 40×32 combination. Perhaps before arguing that something is stupid, pick some numbers that prove that?

    I don’t see any reason to not just GET X01, and I generally am a hater of all these adapters, as 1×11 is amazing, and this stuff results in ghetto-rigging derailleurs into massive B-Screw hacks and crappy shifting since the derailleurs aren’t designed for these >36t cogs…

    That being said, I hate even more people on the internet arguing about gear-inches and gain ratios like no one else on the internet knows sheldonbrown.com/gears exists…

    Get a hobby!

  13. James S on

    Hery Goridebikes, I did prove it with actual numbers. Do you not understand gear ratios? You don’t need to use Sheldon Brown’s calculator at all. Simply divide the chainring by the rear cog and compare that ratio. That’s exactly what I did and it quite clearly proves my point. In fact, the manufacturer himself admits that you don’t improve your range by using the 13 tooth lockring. (See his comment above).

    So yes, you can get almost the same range and gear ratios either by using a 13-40 cassette with a stock 32 chainring or by using an 11-36 cassette with a 28 tooth chainring. What you don’t get is an increase in the range, which is what most of these cassette adaptors with 40 and 42 teeth large cogs (and this adaptor without the 13 tooth lockring) are designed to do.

    I guess my real hobby is getting frustrated that so many people can’t figure this stuff out WiTHOUT referring to Sheldon Brown’s calculator. Is it really so hard to divide two numbers and compare the result?

  14. absoluteblack on

    James S – what to say. Your gear calculations are right… but not entirely related to reality.
    what you are not aware of is that lots of people already use >32T up front. So once you have a small gear up front there is no way to get smaller.

    Such riders in most cases want to have a gear up the rear to help them climb long uphills. And this is what we offer without weight penalty other solutions have. You also have to realize that people who do use sub 32T ring up front are not into high speeds on the flat… otherwise they would have bigger ring or 2X system .

    If it does not make sense for you it is absolutely fine with us. We understand it. But there are thousands of other people in the world (not only in your particular location) where it absolutely make sense:) Sometimes you need to look at big picture. Like someone once wrote ” the eye has to travel”, otherwise you just look at stuff you know already know and don’t progress. What is not good for you it doesn’t mean it is not good for others.
    just my few cents…
    to finish this post i will just mention that you CAN take off 17T for eg and leave 11T. In such case you get 11-40 which is bigger than 11-36… we give people options. It’s up to each of you what you choose to take off from cassette. And this is a beauty of this system!

  15. absoluteblack on

    goridebikes – with our adapter all you have to do is 1 turn of B-tension screw, simple. Or sometimes even not that.

    No additional longer screws, inverted bolts, massive adjustments etc.

  16. THAT GUY on

    Amazing that the know nothing know it all crew can’t even fathom the concept of having multiple wheelsets constructed of varying components geared (nuk-nuk) for different applications.

    I mean, why just swap your wheels out and call it done, when you can add swapping your chain ring along with them?

  17. craigsj on

    It would seem to me that a better 4-cog upgrade to 40T would be a 25-29-34-40 rather than what’s being offered here. With that solution you just use the lower 6 cogs of a Shimano 11-34 or 11-36 or the lower 6 from a SRAM 11-36. You don’t have to ditch the 15, 17, or look for a 16 to replace both. Gear spacing is what you want as well. Don’t know why anyone would go through the trouble of doing a 4 cog 40T and offer spacing like this.

  18. absoluteblack on

    craigsj – XT has one of spiders with 19-21-24. So you cant use 6 original cogs the way you propose.
    SLX would require braking apart riveted cluster by hack saw. This is not many people want to do or can do.
    Only one left is sram 1050 which after conversion works heavier than XT and requires to buy new cassette if you have anything else than 1050.

    So all in all we went with gearing people are used to already and modification is simple and not expensive as this part is the only needed one for conversion.
    Jumps of 4 teeth are also much more predictable for the rider rather than 4-5-6 at the end (that’s our subjective opinion of course).
    Our proposition 13-40 has jumps of: 2-2-2-2-3-4-4-4-4 that makes a very consistent change when you climb.

  19. Ayyggss on

    Absolute gets my vote just bc they shut all of your statements down with logical answers . People always think if it isn’t good for them it isn’t good at all .

    I ran a 30t bling ring on my bike to get that lower 30-36 climbing gear . When I hit the descents I would spin out that 30t so I ended up swapping it out for a 32 . My cadence feels better now and I get a 1-2 mph bump ( not much bit it feels better ) the 40t makes more sense for a std rear mech (non xx1/xo1)

    The main thing people forget is . If you want super low hearing with great range . STICK TO A 2x or even a 3x system . All the range you need !

  20. craigsj on

    OK, but I’d rather work to get something I want than to settle for something I don’t. That won’t be your product.

    Leonardi produces a 25-29-34-40. They realize you don’t want close ratios in a wide range cassette with a giant hole in the middle. A 13-40 has the spread of an 11-34…the same mistake they made with 10speed in the first place.

    Since 10 speed was introduced the 11-36 was too narrow a range. They should have taken the 11-34 spread and added a 39 or 40T to it. Now what we see is botched conversions. We need the cogs from a 9s 11-34 with a 40T added. It’s obvious.

  21. absoluteblack on

    @ craigsj . Like i wrote before this is something you want:) and that is fine. Saying “we” does not represent all customers combined. Like i also wrote before range does not matter here much. It’s rather not a product for people who race or have one bike to ride on the road/commute and trail. This product is for people who ride trail or enduro and they realize that they don’t utilize low end of cassette much, but need that extra gear to go steep climbs. Simple.

    We have ridden Leonardi product and still decided to make 28-32-36-40. It’s more universal, one piece fits both Sram and shimano cassettes, it’s lighter, it’s cheaper and gears are more predictable as you are used to them already if you had 11-36 before. If everyone would want same thing from each segment of life there would not have been that many companies… right?

    We want to thank all for such a great response to the product and decided to extend giving free lockring to the first 400!! orders. Not much left so hurry up:)
    At least you can check yourself how much fun is to ride with 13-40 for free. Remember, you can always put 11T back and take off 17T if you want to.

    Have a nice Sunday all and go ride your bike.

  22. Jesse Edwards on

    Kinda surprised at all the hate up in here. The simplest way for me to get an easier gear on my bike without buying a new crank and new chainring was to buy a 100$ 42T ring for my 10speed cassette. After a few rides, I didn’t love the shifting in the middle, and decided to ditch my 11t cog for a 13 one, as I rarely if ever use it on the trail. So for 120 bones I now have a 1x set up that works well and allows me to ride better up steeper/longer hills on my 29er bike. 1×11 may be cool and all, but would have been 10 times the money for essentially the same upgrade. End of story. Any haters up in here actually buy one of these things, or are they just sitting around spouting off?

  23. XcSgCyclist on

    Hi I recently upgraded my cassette with ab adapter…well I’m always having problems with my 28t of the adapter…when I put in power to climb, the chain keep skipping as if the chain won’t bite in to the cassette teeth..what could be the problem? Anyone can help me with this?
    Much thanks! 🙂

  24. Terence Ang on

    I am having the same problem of the chain skipping at the 28T cog while climbing. I am a pretty light (and weak) rider…

  25. ASBrooks on

    Since the spacing on an 11 speed cassette is almost the same as a 10 speed cassette, could I not use the ab adapter with the remaining 11 to 24 cogs and make an 11 speed cassette?


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