Hands On: OneUp’s Cassette Changing, XX1 Challenging 42t Adapter Sprocket

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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!

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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.

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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.

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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.

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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!


PBJoe - 12/10/13 - 9:05am

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.

Brian - 12/10/13 - 9:05am

What they need to do is ALSO offer a 16t cog to replace the 15 so the jump isn’t so great!

24s - 12/10/13 - 9:16am

“What they need to do is ALSO offer a 16t cog to replace the 15 so the jump isn’t so great!”
that’s it !

vtt attitude - 12/10/13 - 9:34am

That looks great ! 10 speed from 11 to 42 is enough for most of the trails.

1speedlos - 12/10/13 - 10:28am

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!


M - 12/10/13 - 10:47am

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

Sevo - 12/10/13 - 10:57am

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.

Alex - 12/10/13 - 10:58am

Why not offer a 40t so that the jumps are the same from the 32 to the 36 to a 40?

Keith B - 12/10/13 - 11:11am

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.

Shawn - 12/10/13 - 11:16am

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???

Simon - 12/10/13 - 11:16am

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)

gexal crankshaft - 12/10/13 - 11:38am

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?

Ripnshread - 12/10/13 - 12:47pm

Maybe I’m a little cracked out, but every time you mention 12 shift ramps I only see 6. ???

Steve @ G4G - 12/10/13 - 1:01pm

When you post the first ride impressions, be sure to mention what ring(s) you’re using up front!

jason - 12/10/13 - 1:07pm

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.

OneUp - 12/10/13 - 1:30pm

@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.

Oliver - 12/10/13 - 1:40pm

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.

Jeff - 12/10/13 - 2:05pm

Most important – does the green anodizing match the RaceFace green wide/narrow ring?

RUSTYDOGG - 12/10/13 - 2:57pm

+1 Jason. But you left out the 30%+ in Fed/state taxes take.

LULZ - 12/10/13 - 3:07pm

Couldn’t they just include a serrated 12t cog and lockring, so you could keep the 17t, and lose the 11, which no one uses?

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