Wolf Tooth Components GC 42t tooth cassette adapter805

Since it looks like Shimano might be more focused on competing with GoPro on cameras than with SRAM on XX1 competition, 42t cassette adapters may be here for a while. Even if Shimano were to come out with a viable answer to XX1, there would still be plenty of market for adapters like Wolf Tooth Component’s GC thanks to the ability to expand your 1x or 2x options on the cheap.

Why not just go with a smaller front chainring? The benefit to a cassette adapter is the wider spread of gears that the 11-42 provides over say an 11-36. In testing the spread offers high enough gearing for riding the road to the trails, but low enough that in most loose situations the rear wheel will struggle for traction before you run out of gears. After riding a few 42t cassette adapters for 2 months, I won’t be giving up the cassette adapters any time soon.

How does the new Wolf Tooth Components GC compare? Find out next.

Wolf Tooth Components GC 42t tooth cassette adapter806

Thanks to the huge profile of the 42t cog, and the aftermarket nature of the big ring, the shifting up to the bail out gear is called into question. Fortunately the Wolf Tooth Components GC offers lighting fast shifting which is a direct result of the amount of detail put into the machining of each tooth and shift ramp. This is where the GC is set apart from the competition, with smooth, silent shifts up to the 42t GC – so much so that you’ll probably look down to make sure that it is actually in gear. The shifting on the rest of the cassette is admittedly softer than stock thanks to the increased b-tension, but in my experience it hasn’t been a deal breaker. Honestly, it sort of makes the 10 speed drive train feel like you’re running 9 speed – shifts are just a bit more clunky and not as laser fast as we’ve come to love from Shimano Dyna-sys. Would XX1 shift better? Yes. But when you start adding up the price for an XX1 conversion, the $89 Wolf Tooth GC looks pretty appealing.

Wolf Tooth Components GC 42t tooth cassette adapter803 Wolf Tooth Components GC 42t tooth cassette adapter802

Wolf Tooth Components GC 42t tooth cassette adapter798

Anyone who was initially concerned with the OneUp or GC cassette adapters damaging the splines on your freehub body need not worry. After quite a few miles, my freehub body is looking as good as new. As an added benefit, the fit of the WTC GC is very precise around the splines which should only help to prevent any wear and tear. Keep in mind that unlike the OneUp, the GC is Shimano or SRAM specific. While not quite as convenient, Wolf Tooth mentions that trying to make a cog that shifted to their liking that would fit both cassettes proved impossible. By keeping it to one or the other they were able to fine tune the shifting teeth and ramps to each cassette for precise shifting which really shows in the final product. An added benefit of this design is the lack of any spacers needed for the GC – just remove the 17t cog and spacer from the cassette and you’re good to go.

Because the GC is Shimano or SRAM specific, the Shimano version is only compatible with 10 speed 11-36 XT or XTR cassettes, while the SRAM version (also $89) is compatible with  X5, X7, and X9 10 speed 11-36 cassettes.

Wolf Tooth Components GC 42t tooth cassette adapter799

Wolf Tooth Components GC 42t tooth cassette adapter804

The GC also has a leg up on the competition when it comes to the b-tension screw since a longer, 25mm screw is included with the cog. More than just a longer screw, it is also an allen bolt which makes dialing in the b-tension easier than the stock flat head screw. A word of caution though, make sure to thread the bolt in by hand to start, it would be easy to cross thread which would result in a very unhappy rear derailleur. With the new bolt in place on my XT Shadow + rear derailleur, there was plenty of adjustment to fine tune the chain wrap so that the cage would clear the GC. For more installation advice, head over the GC tech page.

Wolf Tooth Components GC 42t tooth cassette adapter800

At 86 grams for the cog (minus 20g for the 17t and spacer) you end up with a cassette that is 66g heavier than stock. The GC is a bit heavier than say the OneUp (73g) which they claim is due to wanting to ensure the cog is plenty stiff and durable.

Overall, the WTC GC seems like a winner with excellent shifting, a replacement b-tension bolt, and the made in the US quality we have come to expect from Wolf Tooth. The only problem you’ll run into is getting your hands on one – all of their current shipments are sold out. WTC will be running a new pre-sale around Feb. 14 and you can sign up for an in-stock reminder on their site.




Wondering what the GC will do for your gearing? Check out the handy gear range charts WTC made up with 29″ wheels up top, followed by 27.5″ and 26″.


  1. Or you could use a cassette that’s designed to work with your rear derailleur. These things are d-u-m-b dumb.

    It’s not just about chain wrap capacity, it’s also about max cog size.

    A legitimate website wouldn’t perpetuate bad ideas, but instead educate and encourage people to use things that are compatible with one another.

  2. Shawnshank, Shimano won’t release a cassette adapter, it would be a new cassette. Which will probably be 11 speed, which won’t be compatible with 10 speed, which will need new shifters, chain, probably a crank, etc. No, I’m thinking there will be plenty of people still using these even then.

  3. C’mon folks, if you don’t have anything nice to say, don’t say anything at all… Bikerumor is a legitimate website that offers up outstanding advice and information. If you don’t like something, just shrug and move on, sheesh. I’ve been running the Oneup now for about a month without any issues on my XT set up. A good customer of mine has a wolftooth on order and I can’t wait to install it for him. Great products that offer affordable solutions!

  4. Sounds like some people are not aware that this enables you go 1×10 with no chain guide when paired with a Wolftooth narrow wide chain ring which saves over $1,000 over getting the complete XX1 group

  5. shim fans just wait until May.. it’s coming
    i run 1×10 xtr and before that, years of 1×9… but im not happy with the chain stress

  6. Glad to see these- for a couple hundred bucks and a very small negative change in shifting performance, you keep most of your gear range and lose a big chunk of weight.
    @Shreddie- they obviously do work, which means they’re compatible. The surface area, not to mention the volume, of the real world where people ride bikes and choose what works, is much bigger than that of the compatibility tables you’re into.
    @Shawnshank- obsoleteness is an idea the bike industry pushes on you to get you to buy more stuff. I am still riding 3×8. It’s obsolete- and still works the same as it did before. The gap in performance between, say old suspension or old brakes and new ones is so big that a person on an older bike can’t keep up with a person on a new one. The gap in performance between a person riding 3×8 and a person riding 2×10 or 1×11 is nil.
    And besides, once Shimano comes out with its own stuff to compete, plenty of people will still own “obsolete” but free (they already bought them) and fully functional older drivetrains.
    @MGK- the lowest gear on a 1×11 is a little higher than the lowest gear on a 2×10, so your complaint has no basis. Buy a calculator.

  7. Wouldn’t it make more sense to replace a rear cluster of 3 cogs to space them more evenly up to 42 (like with a 33 and 37 or 38 cog before the 42) ?

  8. @Tim – Great comments!
    I would add that there is a performance gain by going to 1×11 compared to 2x and 3x, and that is the weight lost. (But this weight will likely be added back on the bike by a dropper post)

  9. I’m happy with my 2×10. I was happy with 3×9. I was happy with 3×8 and 3×7! All these revolutionary changes in gearing are just marketing to sell more components. Modern stuff definitely shifts better than older stuff, but ultimately, I have just as much fun no matter what gearing my bike has.
    I’m no longer a racer, so I don’t mind having to walk up a hill every now and then. It’s also pretty rare I drop the chain off the front. It happens occasionally, but so what?
    Don’t get me wrong, I’m not a luddite (maybe a little), I just think people get way too hung up on having the latest and greatest stuff.
    Is suddenly having a 42t cog in the back really going to make your ride more fun?

  10. One thing that people are clearly missing here is the freedom dumping a FD gives to frame designers. We are already seeing 29er frames with the FD as with a bonkers set up (Specialized Enduro 29) or simply not present and they seem pretty popular and well reviewed. With larger wheels, 29ers and, to a certain extent, 27.5, shortening the length of the chain stay makes a big impact on handling. Large ratio 1x drivetrains make these kinds of frame designs work well while maintianing gearing spread. So basically your 2x or 3x drivetrain is NOT superior or even equal. These large cogs enable someone to run advanced large wheel frame designs without the expense of a whole new drivetrain. Expect to see more frames in the future that cannot equip a FD.

  11. @Pete- another plus is that the difference between the angle the chain makes in smallest gear and the one it makes in the biggest gear is much smaller on 1x setups, which means the rear suspension designer doesn’t have to jump through as many hoops to figure out how to decouple the rear suspension’s compression and extension from the angle of the chain.
    Two big benefits- less weight, better for rear suspension bikes.
    @Will- sure, it’s about selling things, and no, the improvement is not as big as the jump from V-Brakes to discs, or from late 90’s suspension to mid 10’s suspension. But it is an improvement, and the prices will come down. Heck, these bolt on 1x setups make the price pretty darned affordable. I am all for.

  12. Wolftooth, Please post a video That shows how flawless is the jump btw 36 and 42.
    Btw Sram king of marketing. I would be very impressed if for once they would put out something That actually works well when you use it. Not when you read about it.

  13. Advanced frame designs cost at least as much as a new XX1 set up. Front derailleurs on EXISTING frames become a huge mud shelf running way close to the rear tire.
    Too bad you couldn’t just add a 42 to a 9 speed 12 -36. possibly by swapping the individual spacers between cogs?
    I don’t personally think I would like to jump from a 15 to a 19. That 21% differential kinda kills momentum in the middle of the cassette.

  14. “Graves – 02/11/14 – 10:35pm
    Shimano has an answer to XX1, and it’s called XTR.”

    Nice try. You obviously work in Marketing, not Engineering.

  15. @Pete – A valid point. Sure, 1x drivetrains will allow suspension designers some freedom, but this (and the OneUp) are retrofit kits, which would typically mean you’ve already got the frame and everything but a giant cog.
    @Tim – I actually think the jump from cantilevers to v-brakes was more of an improvement than from v-brakes to discs, but they’re all pretty incremental. Gears help you go forward, brakes help slow you down, suspension helps you go faster or be more comfortable. Don’t get me wrong, I’d totally love a tricked out, modern full suspension bike with XX1, but I still have a hell of a time on my 2×10 hardtail. Would I have MORE fun on the latest and greatest bike? Maybe, but I can’t afford to find out!
    Don’t even get me started on all these 10k carbon road bikes…

  16. @ patrik
    funny you mention marketing, since is what SRAM is all about.
    I still haven’t found anythingSRAM that works are as well as hyped.
    Wondering why all pros run small hidden chainkeeper with XX1…

    Besides all considerations regarding frame design without front derailer (which are minimal)
    what about chainline? SRAM and Shimano, both road and off road do not seem to care about it, but if you ever rode Campagnolo you may know the difference. Chainline is more important than all “innovations” I have seem in a while.

    Wolftooth, could you post a video with derailer set up and shifting quality?
    My only complain is the black adapter, it make it look like a cheap shimano cassette.

  17. So I’ve been debating going to one of these systems for a while (not sure I really need more than 11-36 with how long-legged my bike is, past a certain point, it’s geometry keeping you from getting up that hill, not lack of gearing) but I think I’ve convinced myself that if I decide I do need the extra gears, I’ll go with a Canfield hub and a 9-36 x 28: you get to keep normal b-tension, short cage derailleurs, and get increased clearance up front with a smaller chainring. I dunno, food for thought, and keep in mind, I’m doing this on a 26″, so you’d have to go smaller up front to get the equivalent gearing with bigger wheels.

  18. @Shreddie: it sounds like you have a lot of experience with these setups. Please share the issues you’ve had- all of the reviews have been very positive, so it would be good to hear from someone else with a different experience. Have you ridden more than one of these big cogs? What brands caused you trouble?

  19. i think better idea is to just MAN UP!!! lol i rode 1×10 with a 32×11-36 and had no problems with climbing or descending. Spin Spin!!

  20. Pfft, with 1×10 I need a higher gear. Sucks when frames can’t take more than a 32t ring. Spinning out at a little over 25 MPH is a bummer, when I’ve reached 35+ MPH before on the same section, and spinning a higher cadence can throw off your balance/footing when you hit bumps. I’m beginning to think that 1x conversions are for the kewl mid-life crisis guys who splurge on trendy stuff and want to satisfy their ego with things that provide instant gratification. I’ll stick to full gears until XX1 becomes affordable.

  21. For those here critical of the Wolf Tooth and OneUp 42t offering: WTF?
    Myself and obviously LOADS of other people have made the switch to 1×10 and will never ever go back to a front FD.
    Now for less than $100 these two companies have given us the option of getting nearly the full benefits of the hugely more costly 1×11 system. How can you be critical of that??!
    Of course it’s not perfect but from all accounts pretty damn good.
    Oh wait, there is a problem with them — try getting your hands on one. They sell out as soon as they’re back in stock.

  22. So the SLX rear derailleur has max capacity of like, 44t. Excluding factors such as weight, shiny, etc; would using an slx rear der eliminate the need for such sever b tension adjustment and keep the shifting nice throughout?

  23. @Tim,

    You need to study more suspension kinematics.
    A singlering up front if bad for the antisquat. Having a small ring (more anti squat) while you are climbing (more sag so less anti squat) cancel each other. Not so on a single ring setup.

    Moreover pedal kickback with small ring and a small cog in the rear is not so good.

  24. Losima -Pro’s run small keeper with XX1 because they can’t take a chance on something causing the chain to come off. My XX1 chain has never come off while racing or riding, but if you jam a stick or paper in the front ring it is possible pop off. I think WT has done their homework, 1x what ever is the way to go for so many reason’s !! 1X11 Sram XX1 is the only Sram product I would ever buy. Shimano holds up much longer, does all their own design and testing.

  25. For those interested, it’s now official: Shimano will release 3 different 11-speed XTR groups in 2015. I think I’ll wait until then…

    Although I find the 1×10 switch very tempting, it’s not THAT cheap if you’re not already using a 10-speed group. For me, it means changing the crankset (to be able to use a 30-tooth chainring if needed), cassette + Wolftooth GC, rear derailleur, chain and shifter… about $600.00 total if I buy some used parts.

  26. Wolftooth should try to get hold of a pile of 18T cogs (Shimano makes them for their 12-23 10-speed cassettes) and include them with the 42T GC. Shifting wouldn’t be ideal but would still work well.
    @Dave, SRAM designs and builds their products. They have two factories in Taiwan and one on the mainland. I see a lot of SRAM bashing here, but these days XX1 is selling better in the aftemarket than any other group, road or mountain (I don’t know about OE sales). Must be working well for a lot of riders.

  27. I’ve been running the OneUp with a RF narrow/wide in front (SRAM X9 clutched rear der). I thought I’d few things I’d share are:
    1. The X9 b-tension didn’t have to be dialed out very far to achieve the right spacing. The rear der is definitely not being stressed, or adversely effected by this setup. I can’t speak to a Shimano setup, but I’m guessing that it’s fine.
    2. Shifting is flawless with my OneUp, and it sounds like the WT 42T is even better. We live in a cool age where aftermarket engineering is going in some really good directions including direct mount narrow/wide chainrings, etc…
    In summary, I dropped a bunch of weight, got about the same gearing range, and I have a lot less stuff that can break. $130 well spent.
    @Ziotijer – It’s a 1x setup same as 2×10 range…it’s not exactly “Rat Dick” for weenies.

  28. I just swapped the 3×9 drivetrain on my Cannondale CX-1 for a 1×10 WolfTooth setup. I used a Shimano XT medium-cage derailleur, Shimano ZEE shifter, and an Osymetric 38T front chainring (it’s a city/gravel bike.) The shifting from the 36 to 42T cog is absolutely amazing. I find myself using the 11T and 12T cogs a lot more, but never find myself needing anything higher. The 42T is plenty low enough.

    A couple notes that may be helpful to others: cranking the derailleur back with the B-screw has a surprisingly negligible negative effect on shifting, but only if your chainline is perfect and your cable routing is clean. I had to adjust my bottom bracket 1-2mm to avoid having the chain rub on the second cog when it was on the first (that’s 10sp cog spacing issue rather than an effect of the WolfTooth cog.) My Cannondale also had internal cable routing that caused the cable to rub on the downtube (which wasn’t a problem with 9 speed, and probably wouldn’t have been with the 10sp if the derailleur wasn’t cranked back) but caused some random alignment issues/noise with the 10-speed rear derailleur. I ran cable housing from the shifter right to the derailleur, and now it shifts fine.

  29. I’m building an el mariachi with a NW 32 up front and a wolf tooth 42 on the back, but it am not sure which rear derailleur to use. I do not care between shimano and SRAM. I need to know what cage length

  30. Guys…..it works really well…42 GC on both a Shimano and SRAM cassette now. Easy to setup. 1×10 on both bikes now, 34 for the hardtail and 32 for the dualy up front.
    You seriously would not know you shifted to 42, is really that good. Great product that gives you a larger spread (15%) on your current cassette.
    Why the resistance?
    1×10/11 will be standard soon?

  31. Love my oneup 40T with 34T up front on my epic so much that on my new Stump Jumper i’m going Wolf 32T up front 42T in back on XTR when I do leadville this year. Been riding the oneup 40T for about 3 months and I use to look down to see if it made it up there because it was so smooth I wasn’t sure it went up.

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