If you’re looking to put together an expanded range 1×10 system from your current setup, this provides a good alternative to single cog adapters that make a big jump at the top of the cassette. This one provides a smoother transition onto the larger cogs and a more subtle change between the top four cogs, too.
And, it’s a fairly reasonably priced way to do it. The SRAM 1050 cassette retails for $85 and the AbsoluteBlack adapter for $122, putting you all in at $207. Your alternatives for bumping up to a 40T or 42T cassette are either Shimano XTR or SRAM XX1/X01/X1. With Shimano, the cassette is about $300, and it’s 11-speed only, which requires new chain and chainrings, too. SRAM’s is also 11-speed only and requires a new freehub body, chain and chainrings. Either way, it’s going to cost you a lot more.
As for the range only being 40T and not 42T, you could just opt for a slightly smaller single chainring to compensate, which makes even more sense if you’re dropping the 11T cog off the bottom of the cassette as I did. I found the new range to be very good for our local trails, keeping me mostly in the middle of the cassette.
Another benefit? It can add up to a lighter system than the stock cassette…
The Absolute Black cassette cluster is CNC machined from 7075 Txx aluminum alloy and replaces the largest three cogs on your cassette with a four cog unit consisting of a 28-32-36-40 combo. Because of that, you’ll need to remove either the 17t or 11t cog to make it work.
AB only recommends using it on the SRAM PG1050 or Shimano XT/SLX cassettes. I tested it on the SRAM PG1050, which has a three-cog cluster at the top, making it an easy swap. Since I wanted to keep the smooth transition across all gears, I opted to remove the 11t cog at the bottom, made easy thanks to AbsoluteBlack’s 13t lock ring:
The oversized lock ring retails for $18 and is a beautifully machined piece of metal with a larger diameter to hold the larger 13t cog in place securely. Now, there’s a catch to setting it up this way, but first let’s take a look at the parts and weights…
ACTUAL WEIGHTS & DETAILS
The cassette cluster weighs in a 149g and the oversized lock ring at 6g.
For comparison, the 3-cog cluster of a stock SRAM PG 1050 cassette is 177g, so you’re saving 28g even with the larger cogs. Most likely you’ll want to use the 13t in place of the 11t, so there are a couple grams gained back…but it’s still a lighter system overall. They have a complete weight savings comparison chart on the product page showing a lot of different stock and competing 3rd party options.
The adapter basically just adds a 40t cog to the end of your normal 36t cassette, but presents it as a solid unit for crisper shifting and lower overall weight.
The front makes it look pretty chunky…
…but the rear reveals the beautiful CNC work AbsoluteBlack is known for.
The teeth are ramped and shaped to facilitate chain movement, but they do warn that shifting won’t be quite as quick as with the stock steel cassettes, and that they shouldn’t be shifted under extreme loads. The rider-plus-bike weight limit is 200lbs (90kg).
So much detail on such a small piece.
INSTALL NOTES & OPTIONS, OPTIONS, OPTIONS
If you’re wanting to ditch the rarely used 11t cog from your cassette, AB recommends going with the XT or SLX cassette, saying the SRAM 13t cog doesn’t have the proper spline interface to ensure adequate purchase on the freehub body under hard pedaling. Therefore, they recommend removing the 17t cog when using the SRAM PG1050 cassette. But, since all I had available to test it with was the PG1050, I took a closer look and have decided to continue running it at my own risk. To be clear, neither I, Bikerumor as a whole nor AbsoluteBlack is recommending you do this as it’s almost certainly voiding more than one warranty, but here’s why I’m fine with the risk: SRAM’s 13t cog actually has larger, wider splines than Shimano’s, providing a broader contact area. But, honestly, I’m not sure that matters…
…since the actual spline contact area on most every hub is going to cut short of hitting the end of the freehub body. So, there’s plenty of overlap and the same if not more contact area as with the XT 13t cog. Proceed with this hack at your own risk.
Why did I risk it? Because I almost never use the 11t cog, and keeping a smooth two-tooth transition across the entire bottom section of the cassette makes for smoother gear changes and better cadence consistency.
Here’s why you can’t just ditch the 13t cog – it has a lip that fits into the recess on the 13t cog and this design characteristic is the same for both SRAM and Shimano cassettes. So, you’d end up with the too-wide gap between the 15t and 11t as shown above.
Other than that restriction, you’re could (again, at your own risk) experiment to find the gearing solution that works best for you. Here’s what a few options look like. And you could always use an aftermarket 16t cog to replace both the 15t and 17t and keep a more natural transition while maintaining the 11t at the bottom. Decisions, decisions.
One final install note: It fit very, very snug sliding onto the Ringlé freehub body, but slid more easily over a few other hubs I tried it on just to make sure it wasn’t a bad fit overall. After a little persuasion, it got past the first 1/3 of the FH body and slid more freely to the edge of the hub.
On the trail, shifting was pretty good between cogs on the cluster, even with a well used chain mated to both a brand new cluster and brand new PG1050 cassette section.
There’s a definite tinging sound to let you know you’ve gone from the steel to the alloy cogs on your way up, along with minimal hesitation between the two. With a solid push of the shifter’s thumb lever, though, it’s not enough of a pause to be an issue. There doesn’t seem to be any of that hesitation going back down the cassette to harder gears.
Overall, it feels like a solid way to add gear range for the big days in the mountains while dropping a few grams compared to other oversized options. Time will tell if those weight savings come at the cost of durability, but for now it’s behaving just fine.