Just In: Wolf Tooth Components GC 42T


SRAM’s 1×11 system (XX1/X01) has many exceptional characteristics, including simplicity, functionality and smoothness, but the price tag and the requirement of mostly using a full set of SRAM parts for the drivetrain has kept many people away from enjoying the benefits of the product. It didn’t take long for third party companies to jump into the fray to give consumers workarounds for the 1×11 system, so we now have cassette adapters from Wolf Tooth Components and OneUp Components that use portions of a 10-speed 11-36T along with an additional large cog to give a wider gearing range to more closely emulate the SRAM 11-speed 10-42T cassettes.

The Wolf Components GC 42T cog comes in either a Shimano and SRAM specific model, and fits Shimano XT and XTR, and SRAM X5, X7 and X9 11-36T cassettes, and you remove the inner 17-tooth to keep it as a 10-speed system. Another interesting aspect of this system is that you can run it as a 2×10 if desired, though I am not sure what front gearing you might use. The GC 42T cog is made from aluminum, weighs 85 grams, retails for $89.95, and comes with a longer (25mm) steel “B-screw” with a hex head. The cog has six special ramp section around the circumference to aid in shifting, and to keep the cog from digging into the soft material of most freehub bodies it has wide tabs by the spline for better load distribution.

My initial test setup on my Ibis Ripley 29er is an XTR 11-36 cassette, a medium caged X0 Type 2 rear derailleur and an E*thirteen TRS+ crankset with a 32T chainring (original 2×10 was 24-34T).


I pulled the XTR cassette off the rear hub and tossed out the 17 cog and its accompanying spacer. I added the GC 42T cog to the hub, and then the rest of the XTR stack (minus the 17t), and cranked it down to specs. I liked that the GC cog had a small dot pointing at the notch, so it made it easy to line everything up on the free hub body. Swapping everything out increased the XTR cassettes weight by 65 grams (85g for the 42T cog – 20g for the 17t/spacer), which should be about the same weight difference (give or take) for any of the appropriate models since the 17t is usually made from stamped steel.

Note: I located an old Shimano 16t cog in my parts bin, so I swapped out the 15t with the 16t to create a more even range in gearing: 11-13-16-19-21-24-28-32-36-42. The difference in shifting using the 16t vs 15t isn’t really that significant, but does make for slightly smoother transitions.

I wasn’t sure how long of a chain I might need for the 42-tooth rear and 32-tooth front combination, so I bought a new 120 link SRAM PC 1071 chain, and ended using 112 links plus the PowerLock connector. As shown above, that chain length worked fine for both the highest and lowest gearing options.

I replaced the standard B-tension screw with the kit’s steel 4x25mm hex bolt, since it gave me additional length if required, and the toughness of a non-alloy bolt and the functionality of a hex head. I had to play with the B-tension until it shifted smoothly between the 36T and 42T cogs, else it would shudder, and I ended up getting it close to its limit to keep the pulley the proper distance from the cog. I also found it was best to alter the B-tension screw when it wasn’t under pressure, so downshift to the middle of the cog when making major changes. According to Wolf, if you’re using a Shimano derailleur, you might need to reverse the B-tension screw to gain additional length.

Continue reading for more on the Wolf Tooth Components GC 42T and full photo gallery.

About the author: Brian Mullin

Brian likes to push the limits in all the sports he obsesses in, whether it's mountain biking, whitewater kayaking, skiing, or sport climbing. He takes those same strengths and a good dose of insanity to his reviewing and writing on mountain biking products, creating technical, in-depth articles. Whenever he's not on the bike, he might be found watching MotoGP racing, otherwise look for him out on the trail.

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  • Davide says:

    The missing 10 is kind of a non issue. Compare the following gear ratios with 28 vs 30 chain ring and you realize that the 10 gains in respect to 11 are irrelevant:

    1142 x 30 => 2.73 to .71
    1042 x 28 => 2.80 to .67

  • Mountain Cycle Shawn says:

    Rad Dad!!

  • Joel says:

    This is an attractive setup, but A) they are out of stock currently (need to tell suppliers to build up stock before positive reviews on MTBR) and B) I don’t have a sense from the review whether the gear range is enough. Did you miss the 2×10? Need lower or higher? Maybe test 30, 32, 34 front?

    • Brian Mullin says:

      A) The Wolf and OneUp 42T cogs are extremely popular and they can’t make them fast enough, as soon as they make a new batch, they almost sell out instantaneously. If we waited until the supplies were strong, it would be this summer! We feel it’s best to get a review out asap,
      B) I have used a 32 and 34 front, and personally prefer the 32, as I like the granny bailout gearing better. The low gear isn’t as quite as good as my old 2×10 of 24f x 36r, but you do need to compromise to get a better higher range through the middle and smaller cogs. The slightly larger chainring up front lets you spin better IMHO than using a granny (22/24/26), so it doesn’t seem like I need the old 24×36 gearing on my 2×10.

      24f x 36r => .67 and 34f x 11r => 3.09

      30f x 42r => .71 and 30f x 11r => 2.73
      32f x 42r => .76 and 32f x 11r => 2.91
      34f x 42r => .81 and 34f x 11r => 3.09

  • Nibo says:

    Well. It is amazing, however I assume I can keep my derailleur and shifters with this set up?


  • Fluxone says:

    I am using a oneup 42 rear cog with 28 wolf tooth gxp ring up front – these things are an awesome combination – i never want a front shifter again!

    the shifting is in my opinion absolutely fine, truthfully i dont even notice a difference once it is set up properly

    The only real drawback is in the high gear range – for my set up it is only about 62 gear inches which is a bit to low once I get off the trails and onto the double track or access roads. For trail riding this is fine but some people may miss the tall gear – not me though.

    Props to both oneup and wolftooth for great products!

  • simon says:

    i used the 42t rear cog on my bike. setup is a bit of a challenge and shifting performance was not what I expected. After testing it for a while i will go back to 2 x 10 as the shifting performance was my main point of dislike.

  • Nucks says:

    I got the 40t and it works great with no adjustment at all. I Love it!

  • Gee2 says:

    Hi, I have wolf 42T installe on 2014 stumpjumper and it has problems when shifting down. It’s not smooth and there’s a delay when the chain moving up or down on the cassette. We did all the adjustments and still showing the same shifting issue. Has anyone had this experience? Please advice. Thank you.

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