If you’re machining anti-drop chainrings in house, it only makes sense that you would make your own 42t cassette adapter as well. At least, that seems to be the case for Wolf Tooth Components. To go along with their precision machined, made-in-the-US chainrings, chainring bolts, and bash rings, Wolf Tooth has been working on a cassette adapter of their own to expand the gearing options of your 1x system.

Look to Wolf Tooth to give your cassette more teeth after the jump.


The cassette adapter will be called the GC – after all, it is a Giant Cog. Unlike the OneUp adapter, the GC will not use additional spacers, due to the fact that it will be Shimano or SRAM specific. To gain the needed space on the freehub body, the 17t cog will be jettisoned much like the rest. Initially, GCs will be available in 42t only, though Wolf Tooth states that if demand for the 40t is high enough, they may follow up with a second model. Their reasoning for the 42t is that as far as a bail out gear is concerned, bigger is better, and while it is the absolute upper limit with current derailleurs, it does work. They feel strongly about the maximum range being the key benefit to a cassette adapter, and mention that the jump between the 36t and the 42t isn’t as big as you might expect.


The prototype design is machined with both shift ramps, and special tooth profiles to ensure perfect shifting up to the big ring. WTC is planning on offering the GC in at least two colors, though what colors hasn’t been decided yet – input is welcome on the color, what do you want to see? Pricing is expected to be around $90 for each GC which will be made in their Minneapolis facility next to all of their other products.

Mike is gunning for a shipping date in early February, and are holding off on taking orders until the cogs are actually ready. WTC says they had hoped to keep quiet about the GCs development until they were closer to shipping, but the recent launches by both OneUp and Absolute Black prompted them to show their hand – though they did have images up on their facebook page a week ago.

Like the other cassette adapters, the GC will be compatible with the following 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)



  1. IMO the gap caused by removing the 17t won’t be a problem. Since moving to 10 speed I find I am almost always shifting two or more gears at a time anyways.

  2. Make it red, and offer spiderless chainrings in red to match. If a spiderless ring for Specialized FACT cranksets is offered I’m in for both.

  3. Why not offer a 1x kit with the chainring, bolts, GC and a 16t cog to replace 15 & 17?
    Sram specific get the direct mount chainring.
    All in matching colors, except the steel 16t cog.
    Make it happin’, captain!

  4. @ Jeff

    That’s a great idea. I pulled both my 15 and 17t, replacing it with a 16t from an old 9 speed cassette my LBS had lying around. The initial drop from 19 to 15 felt a little bit big, but it feels pretty good to the 16.

  5. I ordered the One Up since it comes in green I couldn’t resist. Nice to see some options in this area. Sram and Shimano must hate these companies right now.

  6. This doesn’t compete with anything Shimano makes, and these companies are little more than one or two-man garage operations, so I doubt either SRAM or Shimano give two shits.

  7. Tim: Yep, that’s a rendering. But the difference between a CAD rendering and a prototype is simply running the CAD file through CAM software and then executing on a mill. Wolf Tooth probably has prototypes already.

    • @Travis, yes, you will likely need to do the same “mod” to the derailleur as the OneUp. Even the 40t cogs you will need to dial the B tension screw almost all the way in, you just won’t have to remove the plastic bit from the derailleur on a Shimano. Both SRAM and Shimano list the derailleur’s max cog size at 36, so technically neither derailleurs are designed to work with 40 or 42t, but they do.

  8. Thought: people who complain about possible poor shifting with this setup- use the SRAM X-1 rear derailleur, and one of these big tooth-count cassette rings.
    Pluses: keep your rear hub (no need to rebuild the rear wheel, either), keep your current chain and shifters.
    Minuses: it is more expensive than just the rear cog.
    Overall price: about 350 bucks- new X01 derailleur and whichever 42t cog.

  9. “the jump between the 36t and the 42t isn’t as big as you might expect.”

    I expect it would be about 6 teeth, glad to hear it’s less…

  10. Hey gravity you would be wrong to think shimano is not coming up with some type of counter move to Sram XX1. These aftermarket companies are helping people keep their current gear relevant. Think of all the early xx1 adopters that dropped big money on upgrading to get that 42t. Cassette, Derailleur, shifter, Crank, and Free Hub body. now I can have a nice 1x set up with nearly the same range and the identical range where I am truly needing it. Doubt I will miss my 17T….

  11. mike
    this after market gear isnt really helping shimano at all, it is more than anything proving how cheap people are with how they are set up a mountain bike. Besides if you are running XT or XTR you are missing out if you have it as a 1X because they have the best front shifting out there.

    I agree shimano is coming out with something, but im also pretty sure they are going to do exactly what sram has done but with their own heavy twist.

    Either way I do this all these cassette cogs are really stupid, and they look and mathematically give your bike so little gear rage ass opposed to a 2X or XX1, this is like those 24 tooth rings people put on XX1 cranks because they wanted the best but could not push race gears on heavy trail bikes.

  12. @ – i “I expect it would be about 6 teeth, glad to hear it’s less…

    I know you were being sarcastic, but its the same jump as an xx1 cassette has from 2nd to 1st so really shouldn’t be a problem.

  13. I am afraid I would be one of those squids slapping a 24T CR on my crank becasue I couldn’t push the 28T up the hills.

    2×10 with an E13 TRSdual guide and Shadow + RD is about as secure a setup I will ever need and gives me more than enough gears as long as I don’t do something dumb like buy a 29er.

  14. “the jump between the 36t and the 42t isn’t as big as you might expect.”

    When talking about gearing, you must think it terms of % change, not number of teeth.
    It’s about a 16% jump from 36 to 42. For comparison it’s about a 9% change from 11 to 10 on the high end. 40t vs 42 is only a 5% difference.

  15. I would like the 40t as well. I don’t want to monkey with my b tension like the42 calls for. Wonder if they tried it with 142plus the rediculous rear hub on my Epic?

  16. @ Jeff nailed it. A kit like that would make XX1 pointless for me. 11 speed, screw that. Also, to anyone that thinks the 15-19 gap wouldn’t be noticeable, you’re wrong. A 4 cog jump at that part of the cassette would suck.

  17. I want a 40! So I can put it on an xtr 11-34. I think it would give me closer gears where it counts for me and a good “bonked” gear. Thanks Wolf Tooth! I love my spiderless ring!

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