OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative616

Judging by the amount of traffic the release of OneUp’s 42t cassette adapter garnered, people are interested. Specifically people who want to explore the world of wide range gearing for 1x (or even 2x) drivetrains without having to shell out the cash for the upgrade to XX1 or X01. By eliminating one of the gears from a standard 11-36 10 speed cassette, OneUp made room for their 7075-T6 aluminum 42t sprocket – effectively turning the cassette in an 11-42. Costing less than other options, the OneUp sprocket looks like a promising alternative to get the lower gearing you crave, but how will it stack up?

Install notes, actual weights, and more, after the break! Updated with first impressions after the jump!

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative606

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative605 OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative604

As covered in our first post, the OneUp ring has 12 shift ramps machined into the surface to help the chain jump from the 36 to the 42t. Laser engraving on the ring tells you which side to place the OneUp spacer, so it’s pretty hard to mess it up.

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative607 OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative608

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative609 OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative610

As for the weight, the 42t sprocket itself comes in at 71g with an additional 2g for the needed spacer. Subtract 20g for the 17t cog and spacer and you get an added 53g for a total cassette weight of 390g with a Shimano XT 771 10 speed cassette.

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative612

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative613

All mounted up the cassette looks pretty normal (with the exception of the obvious green ring) – it’s only when you look closer you may notice the missing 17t. Installation was extremely straight forward, just follow the instructions for removing the 17t cog and a spacer, and make sure to position the OneUp spacer according to the directions printed right on the sprocket. Mount the rest of the cassette as normal, and you’re done.

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To prevent the sprocket from digging into freehub bodies, the OneUp is built with wide spline tabs – quite a bit wider than the steel 17t cog that came off.

OneUp Components 42t Tooth Cog Cassette Adapter XX1 XX0 Alternative614

When it came to adjusting the derailleur, I’m honestly surprised at how easy it was. Somehow I expected it to be more involved to get it to shift properly, but I was happily mistaken. After adding the necessary two chain links to accommodate the bigger gear, the only other step was to adjust the b-tension screw. Realistically, it was more like bottoming out the b-tension screw, but there was just enough adjustment to clear the big teeth without issue on my Pugsley.

I’ll be testing the ring out on a few bikes, but I’m especially excited to try this out on the Pugsley. Ditching the front derailleur on my fatbike was great at first offering no chance of the chain rubbing on the tire, fewer parts to freeze up, and lighter weight, but after I started doing more techy rock crawling type riding, a lower gear would be nice. I’m hoping this is the little bit extra I need to go along with the 30t WTC front chainring.

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Certain frames may require some of the additional steps outlined on OneUp’s Site, since it is pretty close. I would suggest lengthening the chain first before trying to shift into the biggest gear due to the fact that if your chain is too short, the derailleur cage will catch on the sprocket and not function properly.

The $100 sprockets will be shipping out at the start of 2014 if you get your orders in now. When asked about the $100 pricetag, OneUp noted that as the part size goes up, so does the cost of CNC machining. Bigger billets are needed with more machining time needed to mill them down to spec.

We’ll report back this afternoon with first ride impressions!

First Impressions:

Riding OneUp 2

Riding OneUp 3 One Up used

We have had some awesome fatbiking conditions lately, and with a few inches of fresh powder on top of the old snow it was a perfect opportunity to get out and test the OneUp cassette adapter. Riding a similar path to one ridden on Saturday, I can definitively say it was better today with the extra gearing range. The added grunt of the 42t made it possible to stay seated for traction, and power out of some hairy situations like large rocks coated in ice, covered in snow. The absence of the 17t was really only noted when you really thought about it, and the two times I noticed it during the two hour ride I was on the road. Testing it on a mountain bike is next, but for the Pugsley and fatbikes in general, I will gladly give up the 17t for the extra low end. When combined with the 30t WTC chainring up front, the 11-42 spread is just about all I need from riding on clear roads to picking my way through a river bed.

One Up Derailleur mod

The plastic tab pops out easily with a pick. Reinstall B-tension screw without it for added range.

It turns out that with the b-tension screw bottomed out the shifting is close, but not perfect. Shifting up to the 42t was uneventful 60-70% of the time, though every once in a while there was a little whirring as the chain and derailleur hesitated a moment before shifting. Taking OneUp’s advice, I removed the plastic tab inserted in the derailleur under the B-tension screw. Remove the screw completely from the derailleur and the tab pops out easy with a pick or similar tool (I would put it aside for safe keeping in case you need it in the future!). Just in case the plastic tab acts as a nylock fastener for the B screw, I dabbed a tiny bit of blue Loctite on the screw before reinserting it into the derailleur without the plastic tab. With the tab gone, there was plenty of extra room to dial in the B-tension that little bit more, and it now shifts perfectly all the time, every time. OneUp points out that if you still need more B-tension after removing the plastic piece, you can actually install the B-tension screw backwards which will push the derailleur out even farther.

All said and done, the shifting performance of the OneUp system is great – so much so that once you have it set up properly you will have a hard time noticing it while you pedal. If you’re looking for an alternative to XX1 for a wide range of gearing, the OneUp is definitely worth a try.

Drivetrain Setup:

PS – for those wondering, the full 10 speed cassette plus the OneUp adapter does NOT fit on an 11 speed road freehub body. It’s close, but you can’t get the cassette lockring to engage the threads.


  1. PBJoe on

    It feels to me that $100/each leaves a lot of space for othe companies to jump in and undercut. One gear is pretty easily commoditized. Hope this works out for them, seems like an easy solution to a developing need.

  2. 1speedlos on

    Wolf Tooth will be offering a similar product in January/February.
    I agree that this will be a great addition to my Pugsley, and second (third?) the idea of a 16t aftermarket cog!


  3. M on

    Instead of taking out the 17 you could take out the 11 and use a 12th lock ring to keep the cassette in place. Really who is ever running the 11 on the trails anyway. That way you dont get the big jump mid cassette

    just a thought

  4. Sevo on

    BBJoe-Look at what similar sized chainrings (a fair comparison from a materials/machine time stand point) cost in the market….in the 42-44 size. Also note that cutting shift ramps isn’t as easy as you think and adds to the cost. As does the cutting of splines.

    Only person that could undercut them is overseas…..but the volume you have to do is a huge investment to cater to people like us. Majority of the world doesn’t want to deal with this.

    In the end, keep the following in mind:
    -You can sell off most front ders/shifters for almost what this costs.
    -The end price of an XT cassette with this ring is still cheaper than the xx1 cassette by a bit.
    -It comes in green!

    Always remember this peeps, when you’re cheap (I’m one of these people) and can’t buy the big $$$ solution our next bet isn’t always going to be perfect. I do feel they came very close at cost/finish end. My question now is how well does it work? I could afford the xx1 group now…but I also want to get a dog, ski this winter, and I can’t put it on all my bikes. Even at my cost, it’s expensive for one kit. I could buy quite a few of these at retail even and still come out ahead and get that extra gear I want.

  5. Keith B on

    M, the point of this upgrade isn’t the super-low gear that the 42t cog provides, it is the range that the 11-42 cogs provide. You could get a similar low gear with a 26t chainring on an 11-36 casette, if you don’t need a bigger gear than a 26×11.

  6. Shawn on

    This is great if you’re running the 10speed cogs, however, I’m still stuck in the semi-stone age, and wonder if this would work with a 9speed cog set, 12-36 to ??-42, providing I use the proper spacer. Any ideas???

  7. Simon on

    Keep in mind, it is only compatible with these 10 speed cassettes:


    XT (CS-M771-10 11-36)
    XTR (M980 11-36)


    X5 (PG-1030 11-36)
    X7 (PG-1050 11-36)

    X9 (PG-1070 11-36)

  8. gexal crankshaft on

    Do me a favor. Convert a DT mountain wheel free hub to 11 speed with a DT 11 speed road free hub, then try mount that hopped up cassette to it without removing the 17. Does it fit? Could you rig up the new 11speed Di2?

  9. jason on

    Do bikerumor posters that comment on how expensive things like this are have any experience actually making things? Consider that CNC time is going to cost between 60-120 an hour depending on location and capability of machine. Cogs and splines are pretty time intensive to machine, then there’s the shift ramps, plus raw material which in that size isn’t cheap. Then there’s anodizing and laser engraving. He probably left a little fat in there for distributors as well. $100 for that cog as a niche part seems pretty reasonable honestly, especially when you consider how expensive the alternative is.

  10. OneUp on

    @ripandshread – There are 6 obvious positions where up shifts occur. What isn’t as obvious is that each of the locations has features to pickup either an inner or outer chain link. Since the inner and outer pick up features are a tooth apart what looks like 6 is actually 12. Rings with one very sharp up shift tooth can cause damage to the ring if it catches the wrong link.

  11. Oliver on

    Good call Jason – good engineering costs money so unless you can develop and manufacture these things yourself, you should probably just buy the products or shut up. THINGS COST MONEY, companies aren’t in it just for fun, they want to profit from their products.

  12. james on

    Nice but price is high.

    I emailed Works Components about getting some here in the UK (i dont want to pay import – how can they guarrantee i wont pay it?!) – they are making one now and it will be £45 in the UK so quite a bit less and a £5.00 off deal with a chainring.

  13. smilmick on

    I dont like that the b-tension screw has to be set in such an extreme manner. Setting b-tension to accommodate this one extremely large gear will sacrifice shifting in the rest of gear range because now the derailleur pulleys are set much much further away from the cassette than shimano (or sram) intended. Its a neat concept that Im sure will be successful, but I would never run it and I would hesitate to recommend it.

  14. Jesse Edwards on

    I wish someone would just make a 10 speed cassette that was 11-38T or 40T. So stupid to have to move to a whole new system for a couple of teeth, or use this makeshift setup. F you, SRAM

  15. Padrote on

    You aren’t undercutting SRAM by adding a 42t cog to a 10x setup. XX1 is actually built to accommodate a 42t cog and shifts a lot better than this will.

  16. Chris on

    Can’t wait. I ordered the sprocket when I saw your article the other week. This makes me more anxious for it. Cant wait until Mid Jan 2014!

    Will your MTB test use a Med cage?

    I’ll be applying it to a x0 med cage with a 32t front.

  17. Tandumb on

    Something’s fishy here with this company. They dangled a $15 Off coupon on the last post on BRumor (a week or so ago), and now they’re not excepting the discount…. what gives?!?

    I saw BR revised the post as well to delete the offer – but believe me, they DID promise it at one point. Now they’re just out for your cash.

  18. AdifferentMike on

    Hey Sevo: did you happen to notice this part is made overseas? I’d pay 100 bucks if this was made in North America, but it seems pretty overpriced for another part imported from Taiwan.

    Hopefully Wolftooth comes out with their own version soon and we can support some US manufacturing.

  19. ah on

    What about the torque?

    If you have a 30 up front then you can put some serious torque through this thing.

    A good test would be to try riding somewhere steep where you can get maximum grip and see if it can handle all the torque you can put out through that spline.

  20. Jack S on

    James, when they send it to you they will declare it’s value and you’ll most likely have to pay VAT before you will be able to take possession of it.

  21. charles on

    I ordered one. I already converted my hardtail to 1×10, next my all-mountain bike. It’s been a long time coming, front derailleurs have stuck around far too long. It’s road bike technology, nobody every needs 30 speeds in an MTB, let along 20. Just like they never needed quick-release axles, and rim brakes.

  22. OneUp Components on

    Thanks for all the feedback. Sorry for any confusion regarding the discount code. The response was larger than expected and we ended up giving more codes than we had parts in our first batch. Please note, we will honour the code for those who have it until Dec 18th.

    Regarding price, the MSRP includes all shipping and duties to the EU and US/Can.

  23. Jeff on

    Even with the extra width, I bet this will dig into most freehubs. As others have mentioned, $100 is steep for overseas manufacturing. I’d pay half that much but I wouldn’t really buy it because having to replace $100 freehub bodies would get expensive.

  24. Mike C on

    Possible B-limit screw workaround #2: take the screw out and insert it from the other side.

    On 11sp freeub: not even if you finesse the spacer width? (Would only work on the setup with the spacer between the new cog and the 10sp cass.)

    • Zach Overholt on

      @Mike C, no, there is probably 3-5mm of material at least that would need to be removed, and if you’re referring to the OneUp Spacer it’s only 1mm or so.

  25. DM on

    How’s the chain tension when in the 11t cog? I briefly tried a General Lee 42t cog unit with a 30t ring on a single-pivot bike with Shimano XT Shadow+ Med Cage. Because of the chain growth, I had to run a fairly long chain and didn’t like how slack it was in 11t. Perhaps this is a non-issue on a hardtail.

  26. nsxtc on

    I have an X0 cassette (PG-1080) and the 11,12,14 cog is not attached to the spider. So couldn’t I just simply remove the 12T? What other reasons it won’t work on a PG-1080? The way I look at it, 11 and 12 are very close in ratio and with the 42T, the final gearing is 11-14-16-18-21-24-28-32-36-42

  27. Mr C. on

    Zach, put some lube on that bloody chain, before Todd Williams sees it… HAHA! Oh, and I need one of those in RED for my new Moonlander puhleeze!!

  28. MattW on

    Torque is related to the gear ratio you’re using. 30/42 would actually be a higher gear (=lower torque) than 24/34, a gear which I used for years without any issues. YMMV if you’re heavier than me though…

  29. Duane on

    If you were going to remove the 11T to replace it with a 12T, you could have just installed a smaller chainring. You won’t have a bigger range, just a lower gear. The point of this product is to provide a larger gear range. If all you want to do is gear down, install a smaller chainring.

  30. vincent on

    could not find the field to use the discount code, and now it s expired. I found it now.. apparently it appears only if not using paypal.. Not too happy about this. Still very interested to buy.. but I don’t feel like paying 100$ after sending emails to ask about this before Jan 25th and never got any answer.

  31. Robert on

    To all the whiner’s, “STOP IT ALREADY!” Pay the dang money and be done with it. It’s a relatively inexpensive alternative, It’s functional, it’s solid and it looks mighty Purdy up on my ride! If you think you could pop one out on your own, get to it and shut your yap.
    If ya don’t have anything good to say, go complain to your Mother, I don’t wanna hear it!
    Long Live OneUp!


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