Just In: OneUp Components 42 Cog for 1×10 Drivetrains

Components Pro Reviews

The 11-speed drivetrain rolled like a freight train into the mountain biking world when SRAM released their 1×11 XX1 system, and its now joined by the just released X01. The system uses various front chainrings (28T-38T) combined with a 10-42T cassette for its 1×11 gearing. 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 1×11 simplicity and smooth shifting of SRAM’s excellent product. It didn’t take long for third party companies to jump into the fray to give consumers workarounds for the 1×11 system.

The first workarounds were for 1×10 gearing using the current 11-36T cassettes combined with narrow-wide chainrings from Race Face, Wolf Components and others, along with a clutch rear derailleur (SRAM Type 2 or Shimano Shadow Plus). Next came cassette adapters that use portions of a 10-speed 11-36T, and replacing certain cogs to give a wider gearing range to more closely emulate the SRAM 11-speed cassettes. One of the first offerings was the General Lee cassette adapter, which replaced the last four 24-36T cogs with a 25-40T, but it only works with SRAM 1030, 1050 and 1070 cassettes, and costs $200. There are few other options on the market, including the Recon 11-40T cassette, and a couple of smaller companies operating out of Europe with cog replacements of some sort.

The latest and most interesting alternative is OneUp Components single 42-tooth cog, which will come out in January and only costs $100. The OneUp 42T cog fits at the end of the Shimano XT and XTR, 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 cog is made from 7075-T6 aluminum, weighs in at 70 grams, and has 12 up shift points. To help prevent the cog from digging into the soft material of most freehub bodies, the cog has wide tabs for a better load distribution.

The initial 2×10 setup on my Ibis Ripley 29er was a Shimano XTR 11-36 cassette, a medium caged SRAM X0 Type 2 rear derailleur and an E*thirteen TRS+ crankset with 24-34T chainrings.

Test #1

For the first 1×10 test, I used the existing 34T front chainring and the OneUp adapted 11-42T cassette. I left the rest of the 2×10 components attached, to make initial testing easier, and I never used the front derailleur or shifter for anything.

Test #2

For the second test, I removed the front derailleur, front shifter, inner 24t chainring and replaced the E*thirteen 34t chainring with a new Pacenti 32t, which saved 355 grams. Since adapting the cassette to 10-42T adds 50 grams, I therefore saved 305 gram (.67 lbs) over the 2×10 set up that I started out with.

Continue Reading on the Next Page for our First Impressions and Installation of the Product…

About the author: Brian Mullin

Brian has been part of the Mtbr team since 2007, where he has become an integral member of the review and test staff, specializing in technical articles. He likes to push the limits in all the sports he obsesses in, whether it's mountain biking, whitewater kayaking, extreme 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 and hyperbolic articles. Whenever he's not on the bike, he might be found watching MotoGP racing, otherwise look for him out on extremely technical singletrack.


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  • Jake says:

    Would love to see a picture of small small chain slack or the gear it finally does get tension.
    Also can’t wait to see how many morons set the B tension screw while in the small chainring, then go and ride in Big/Big only to have the derailleur eaten.

    • Brian Mullin says:

      Jake – The double stacked picture in the middle of the article shows that exact set up (42×34 and 11×34). Were you asking if I tried doing a 11×24 (my current granny), as I am sure it would too slack? If I was going to try a 2×10 system, I would push the small to a 28 tooth. I’ll need to experiment on that system, but for now I was only doing a 1×10.

  • Hpzie says:

    This one looks much better than the one availble now on ebay for $50. Price still a bit high compare to a nice Hope chain ring only $45.

  • Rod says:

    Instead of removing the 17t, can the 11t be removed?

    • Brian Mullin says:

      Yes, you could remove the 11t. During my test yesterday, I came to the conclusion that I like the 11t too much to remove it, since it gives you some maximum speed when needed.

  • Kurt says:

    If you can find a 9 or 10 speed 16t cog lying around in your parts bin or that of your LBS, subbing that in for you 15 AND 17t cogs results in a much smoother shift, even if it’s not perfect.

  • Steve says:

    You’re still ending up with a narrower spread of gears with this 1x 10 set up than the original 2 x 10. For the uninitiated, what’s the big advantage in losing my front derailleur and a full spread of gears?

    • WC says:

      The advantage is you loose your front derailleur = simplicity. Plus you’ll be more manly because you’re forced to work harder, you’ll build up huge quads, tighter buns and the ladies won’t be able to resist you.

  • Jay says:

    Great write-up… I pre-ordered mine when these were announced, and this article was a great read for more information. Question – wouldn’t you have to add “need a new chain” as a ‘con’? Or can someone just install the OneUp ring with no other extra parts needed? I’m pretty sure one would recommend a new chain regardless – but I’m curious about how much of a difference in links the new chain was from your old one?

  • scott says:

    any idea how this would work with a 9sp 11-34?

  • helbert says:

    Can I use medium cage derailleur?

  • Lyle says:

    Currently have a RF narrow wide front with a Shimano Zee short cage shadow plus RD and an XT 11-36 cassette. Will this work with my setup? I read somewhere that you have to use either a long cage or medium cage RD.

  • Lyle says:

    Thanks Brian! I will give them a ping.

  • flyingsqrl says:

    @ Toshi Eto & Rod, why wouldn’t you just get a smaller chainring. Removing the 11T takes away the range. The point of adding the 42 is to expand the 11-36 to an 11-42.

  • PinkFloydLandis says:

    Re: chain length . . .

    1. Brian, there’s no way your original chain had 112 links plus the connector link. That would = 113 links total. Multi-speed chains must be even numbered by design. So maybe yours was 111, or 113, but not 112.

    2. The need for a new chain will depend on your choice of front chainring. If your front chainrings don’t change, and your chain length was correct originally, then you will need a few more links to accommodate the 42T cog. But if you’re moving from 38/26, 36/24 or 34/22 double to a 32T or 30T single ring (which is a common choice) then you may very likely be OK without a new chain, since the decrease in front chain wrap cancels the increase in rear chain wrap.

  • Max says:

    So, how did it perform? You don’t mention any of your thoughts on the product.

  • Me says:

    I love when people make things seems so impossible. Adding a low gear to your 1×10, OMG! Stupid money for what you get is what I’m thinking.

    • G says:

      Not so stupid if you live in Colorado.

      • vince says:

        I live by the Dark Peak area in Britain – plenty steeps and techy, muddy all over this time of year.
        I went 1×10 with standard 11-36 XT and a Hope IBR 34T after playing with a few options and deciding that a 36T front was a bit tall for me – though I know others that use them fine.
        If you have granny bails, you’ll use them whether you meant to or not. Surprising how often you can get up stuff in fine style if they just aren’t there – although you may find yourself out of the saddle more – which may make this cassette extension more worthwhile for full sus bikes than hardtails.

  • sham says:

    how i can buy this item and how can i be your distributor for malaysian market

  • R says:

    I am very interested in this with a 2×10 setup with a 28 x 42 crankset. Please let us know how this works. Seems to me this would be perfect for people who live in the mountains and also ride some road to get to trails.

  • nsxtc says:

    Why woudn’t it work w/ a PG-1080 (X0) cassette?

    For X0, the original gearing is: 11*,12*,14*,16,18,21,24,28,32,36 (where the cogs with “*” are not attached to spider. Can’t you simply remove say the 12 (I want to keep my 11 in case I want top gear)?

    The result will be with the 42T: 11*,14*,16,18,21,24,28,32,36,42*

    • Brian Mullin says:

      I haven’t tested it, but I would think the 11 to 14 jump would be tough, since there isn’t much ramping on those little cogs. Dropping the 11T could be tough since the next cog doesn’t have the serrations for the lock ring. I have only tested per their directions, and the most I might do is attempt to find a 16T and replace the 15T with that one for a better transition.

  • Jordan says:

    Nice explanation of the system Brian. Can you comment on how well you think this setup would stand up to high levels of torque? My main concern is how well the drivetrain will hold up with the chain in the highest gear, while you’re cranking up a prolonged steep section. Does that sound like a recipe for sheared teeth or snapped chains, or do you think it can take it?

    • Brian Mullin says:

      I am a low torque junkie and have snapped more than my fair share of chains. So far I haven’t had any issues, and I have had this system on some extremely steep terrain, where I have been pushing really hard.

  • Lee says:

    One site suggested removing the 17 and 19, replacing them with a 18T for more even spacing. Only stand alone 18T I can find is one from Miche.

    • Brian Mullin says:

      Depends on the cassette you’re using. The XTR doesn’t have that option since the 19 is a part of a spider. I found an old 16 laying around, and removed my 15 (in addition to the 17) to give me a nice even spread from 13-16-19.

  • todwil says:

    I have the stainless cog from ebay and I just left off the last gear I hardly ever use that one anyway.

  • Netta says:

    I got a “oneup ready configuration ” with front 30t narrow/wide and XT cassette.
    The RD is SRAM X7 TIPE 2 but medum cage :(
    I wonder if it can fit me?
    Could you advice?

  • I'mRight says:

    Can you tell us how often you used the 42t gear. A 6 tooth change could cause you to wheelie on climbs or spin too much on climbs.

    • Brian Mullin says:

      It would depend on the climb or where you happen to be on a particular maneuver. I use the 42T on every ride, though like any low gearing, on something extremely steep and loose you might need to downshift to the next gear. The 32tx42T offers a .71 gear ratio compared to my original 24tx36T .67.

      This is the same upper gear range as the XX1 => XX1 (10-12-14-16-18-21-24-28-32-36-42) vs the OneUp (11-13-15-19-21-24-28-32-36-42)

  • Taufik Eko Yudanto says:

    Hi Brian, great review… So how’s the result of replacing the 17T with 16T?

  • DoISmellBacon says:

    I’m curious about the options of ditching cogs other than the 17 also, since that is within the range of cogs that I use a lot in “mission critical” off-road situations. Losing the 13 would probably be the best for my situation, as my trails involve a lot of frequent and rapid transitions from descending to climbing, so having all the cogs properly spaced down to the 15, with the 11 on hand as a sort of pavement only reverse bailout gear seems to make more sense…. but even losing the 15 or 11 would probably be better for me than losing one of the cogs that’s within the gearing sweetspot like the 17 is. I don’t have my cassette in front of me, but from memory it seems like either the 13 or 15 could be removed just as readily as the 17. I imagine that the 15 to 11 drop would be pretty clunky, but I don’t think I’d care much…. Thoughts?

    • Brian Mullin says:

      The smaller the cogs get the clunkier the shifting gets when the steps become large. The OneUp 11-13-15-19 is better than 11-15-17-19 or 11-13-17-19. The best I have found is getting a 16T and making a 11-13-16-19.

  • Erik says:

    What 16t cog do you use?

    • Brian Mullin says:

      I had an 16t from an old Shimano cassette. Look for a Miche 16t 10 speed cog, as they’re one of the few companies that makes separate cogs. That should work, though I haven’t tried one.

  • brian says:

    Brian
    since you had issues at first with a med cage RD, would you suggest one to just use their long shadow plus?

  • todwil says:

    Has anyone recieved there cog yet?

  • mike says:

    Thanks for the review. I have a Ripley too and ordered one last month. My ship date is is Feb 24th. Hopefully it will work out well.

  • White Marin says:

    Any feedbacks if it’s feasible to Short cage RD’s. I’m using Shimano Saint M820.

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