OneUp Shark 11-50T Kit Review: Sharks, Eagles, and Monkeys, Oh My!

OneUp’s Shark 50T expansion kit takes the popular Shimano 11-42 cassette and adds more gear range and smoother shifting. For those interested in (but without the budget for) SRAM’s Eagle drivetrain, the Shark 50T Sprocket and Cage Kit might just fit the bill. Here are Miles’ impressions after a few months of bikepacking, day rides, and dreams of someday tracking down the elusive Sharkeagle…

A few years ago when I was still riding my beloved Surly Krampus (may she rest in peace), I quickly discovered that the stock drivetrain, although affordable, wasn’t completely ideal for the challenges of loaded bikepacking. Thinking back to it, I could have done more with the 10-speed drivetrain that came stock on the Krampus at the time. Tossing on the affordable 11-42T Sunrace cassette would have been a huge improvement from the 11-36T that came with it, and would have allowed me to continue using my shifter and rear derailleur. Another option would have been to grab a smaller front chainring, which would have helped me struggle a little less up some of the steeper hills I encountered. At the time, however, 10-speed expanders were very intriguing to me, so I opted for a Blackspire ReCOGnition Cassette Expander (42T). As you can imagine, the jump from a 36T to the 42T wasn’t the smoothest, even after installing and adjusting the B-tension with the included longer screw. I just accepted that being able to ride up hills fully loaded meant I’d need to accept a slightly clunky drivetrain. On the plus side, it was cheap, easy to install, and allowed me to continue to use all of my other drivetrain bits.

OneUp Shark 50T Kit Review

Compared to just a few years ago, cassette expanders work surprisingly well. The shifting quality is better, the materials and build quality are improved, and they play nicely with the 11-speed drivetrains that often come spec’d on stock mountain bikes. Back in early 2016, OneUP Components released the Shark 50T Sprocket Kit; a cassette expansion kit for those running 11-42T Shimano drivetrains. As it happens, this release came just after Shimano’s announcement of their widely popular 11-46T cassette. Turns out everyone struggles up hills, whether they are bikepacking or not.

  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
OneUP Shark 50T Kit Review

After getting my hands on Surly’s updated 27.5+ Karate Monkey, I knew I’d need to swap out some drivetrain components and make a few other adjustments to fill the gap that my Krampus once served. To be fair, I did ride the stock Karate Monkey (Sunrace 11-42 cassette / Sram NX parts) for five months or so through the fall, winter, and continued into this spring. However, as soon as I saw some rideable dirt clearing on my local trails, I knew it was time to digivolve my Monkey into something much more fun: a Shark-Monkey. Besides swapping the SRAM Level brakes for Shimano XT, I also took the liberty of replacing almost everything SRAM with XT, including my rear shifter, derailleur, and of course my cassette. Normally, I would have chosen Shimano’s 11-46 cassette, but with the option to test out OneUP’s 50T Shark Kit, I opted for the 11-42. Be forewarned, the expansion cog in question is ONLY compatible with Shimano 11-42 (M7000 / M8000) cassettes, not 11-46.

  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review

The kit includes a monster 50T cog and longer cage for the rear derailleur, both made of 7075-T6 Aluminum, and a 18T cog made of nickel-plated hardened steel. With all of this, the added weight is only 89g, nothing I was going to notice while riding. Installing the cassette upgrade is relatively straightforward. First, I removed my stock cassette, mounted the OneUP 50t cog on the freehub, then replaced the 17T and 19T cogs with OneUP’s 18T, ensuring proper spacing between all of the cogs in the cassette. With standard expansion kits, specifically those that aren’t as large as 50T, a longer b-tension screw is everything you need to get your derailleur properly aligned with the larger cog. However, due to the immense size of OneUp’s 50T cog, a longer derailleur cage is included to help take up the chain slack due to the wider range provided by the 50T ring. For those not familiar with the concept of a long cage derailleur, simply put, the length of a derailleur cage defines the range of gears, or capacity—the longer the cage, the more chain slack the derailleur can take up. Since the chain required for a 50T cog is several links longer than that requires fro a 42T cog, a longer cage is required to keep tension on the chain when it’s in the smallest of cogs. Installing the Shark cage isn’t as straightforward as the previous step, but swapping the old cage for the new one can be done in just a few minutes, even with only minimal understanding of what goes on inside a rear derailleur.

  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review

Below is a video from OneUP explaining the process. Note that the video is referring to installing the RAD cage, which is an almost identical process to the Shark cage, except for a few minor steps that are obvious when you come to them. Watch below:

Shark vs. Eagle

After the initial setup and some of time spent fooling around with the b-tension screw and chain length, it was just a matter of dialing in the rear derailleur cable tension. As expected, this process took a little bit more time than standard 11-42 or 11-46 cassettes do. However, a few minutes later I had a fully functioning 11-speed 11-50T drivetrain. Best of all, it can be yours for less than the price of one SRAM GX Eagle 1×12 cassette; or less than half the price of the X01 Eagle cassette, and much less than that gold model. You get the idea.

  • OneUP Shark 50T Kit Review

Besides price, there are some important differences between the SRAM Eagle, Shimano 11-42, and OneUP 50T Kit that are worth mentioning. The first is that 12-speed Eagle cassettes are only compatible with XD Driver freehub bodies, whereas the Shimano / OneUp combo works with standard Shimano freehub bodies. Secondly, SRAM’s GX Eagle cassette uses stamped steel cogs and durable stainless steel pins to hold it all together, a combination that will likely result in a longer lifespan when compared with the XT 11-42, which has an aluminum 42T that we’ve noticed is prone to early wear. And there’s also the difference in gear range offered by the two drivetrain components. Although they offer a similar progression, the 12-speed Eagle provides a tiny 10T for the flats, while both make a sizeable jump from 42T to 50T. Both options provide a monster 50T granny gear for slugging up steep, technical trails, and they also make running a larger than average front chainring (for a 1x system) more realistic, for maintaining proper cadence on the flats and downhills. Running a 34T up front kind of starts to make sense, which I would never touch with a regular 11-speed wide-range cassette. That is, of course, if you are worried about maintaining cadence on the downhills, which usually isn’t a priority on my mountain bike. I complemented the Shark 50T Kit with a tiny steel 28T Race Face ring and some new Aeffect cranks – inspired by some of the benefits of the People’s Liberation Drivetrain Skyler Des Roches wrote about last fall.

OneUP Shark 50T Kit Review

After a few months of use, besides some slight wear on the 50T cog and a bit of cable tension adjustment to keep things shifting, I’ve noticed my chain wearing out quicker than I expected. I was worried this would happen, especially considering the precarious angle my chain is at when running a 28T in the front and a 50T in the back. I plan to continue using the drivetrain into the summer, and will be sure to provide a long-term performance update down the road, but I have a good feeling I will be replacing my chain every 500km or so. Not everyone will choose to use such a small front chainring, and I’d expect that to help alleviate some of this early wear I’m seeing.

SRAM Eagle vs. OneUP Shark 10-50T

If the 455% gear range offered by OneUP Components’ 11-50T Kit isn’t enough, then they also offer a few additions to the kit that boost that range up to 500%, making it comparable to SRAM’s 12-speed Eagle. In short, they both provide the same 50T cog in the back for climbing as the Shark 11-50T Kit I’m using, but add in a tiny 10T for a better range when in the flats or descending long hills. The hiccup here is that Shimano freehub bodies aren’t small enough to accept a cog of this size, which is why SRAM’s XD-driver freehub body becomes the only real option. OneUP partnered with Hope Technology to create the DT Compatible MiniDriver Freehub to overcome this, allowing yet another option to further boost 11-speed Shimano cassettes to something pretty close to 12-speed Eagle.

OneUP Shark 10-50T Breakdown

  • Shark 50T Kit: $125
  • DT Compatible MiniDriver: $40
  • Shark 10T Cluster: $45
  • Shimano 11-42 M8000 Cassette: $96
  • Shimano XT Chain: $33
  • Shimano M8000 Shifter: $65
  • Shimano M8000 Derailleur: $93
  • TOTAL COST: $497

The MiniDriver and 10T Cluster can be used separately from the Shark 11-50 Kit for those wishing for a smaller cog in the back, or paired with the 50T expansion and extended cage for the largest 11-speed range available. OneUp also states that certain Hope and Stan’s hubs are compatible with the 10T Cluster, and users should contact them for more info on their specific hub.

  • OneUP Shark 50T Kit Review
  • OneUP Shark 50T Kit Review
OneUP Shark 50T Kit Review


  • Cheaper than converting to 12-speed, by using 11-speed shifters, derailleurs, and cassettes.
  • Greatly increased gear range, especially when using OneUp’s Shark 10T Cluster and MiniDriver.
  • Shimano freehub compatible.
  • Easy installation that requires no special tools beyond something to remove the cassette.


  • Chance for early wear if you find yourself in the 50T cog often, as it’s made from aluminum, similar to what we’ve experienced with the Shimano 11-46 cassette.
  • Chain will likely need replacing more often than you are used to, depending on how small of a front chainring you run.
  • Requires MiniDriver or other compatible freehub to match the 500% gear range of SRAM’s Eagle 12-speed.
  • Weight 50T + 18T: 80g, Shark Cage: 9g
  • Place of Manufacture Taiwan
  • Price $125
  • Manufacturer’s Details

Buy from your LBS or check prices at JensonUSA

Wrap Up

It’s pretty wild what companies like OneUp Components are coming out with, especially considering the limited range of cassettes on 1x drivetrains that existed just a few years ago. For those who can afford it, SRAM’s Eagle 12-speed will offer an ultra wide range cassette, buttery smooth shifting, and the peace of mind of knowing everything is compatible. For everyone else – perhaps the majority of us – OneUp’s Shark 50T Kit will likely be the next best thing. If you’ve got a Shimano 11-42 drivetrain already, the 50T Kit is going to offer a much larger gear range to make climbing easier or enable you to throw on a larger front chainring to offer a lower gears for the flats and bombing hills. For a steel mountain bike like the Karate Monkey, I opted to run a 28T chainring for some well-earned assistance on steep terrain. I expected clunky shifting and a worrisome chain line, but was pleasantly surprised have nearly the opposite experience. My only real concern is the long-term durability of the aluminum 50T cog, so I’ll make sure to update this post on that further into the summer.

OneUP Shark 50T Kit Review

Have you figured out your go-to bikepacking drivetrain? Let us know in the comments below. Also stay tuned for a much larger roundup on cassette expansion kits ideal for bikepacking…


Bikepacking Gear


Please keep the conversation civil, constructive, and inclusive, or your comment will be removed.

Bikepacking Collective

We're independent
and member-supported.
Join the Bikepacking Collective to make our work possible:

Join Now