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

Components Pro Reviews


I pulled the XTR cassette off the rear hub and tossed out the 17 cog and its accompanying spacer. I then slid on the 1mm OneUp spacer and their 42T cog, and then the rest of the XTR stack (minus the 17T), and cranked it down to specs. I liked that the OneUp 42T cog had a small arrow pointing at the notch, so it made it easy to line everything up on the free hub body. Swapping everything out increased the cassettes weight by 50 grams.

Update – I located an old 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

I wasn’t sure how long of a chain I might need for the 42-tooth rear and 34-tooth front combination, so I bought a new 120 link SRAM PC 1071 chain, and ended using 111 links plus the PowerLock connector (112 total). As shown above, that chain length worked fine for both the highest and lowest gearing options on my medium X0 derailleur.

I knew that I would need to crank out the B-tension screw on the rear derailleur since the derailleur was optimized for a maximum of 36 teeth, and I ended up getting it close to its limit to keep the pulley the proper distance from the cog. While in the stand, the derailleur shifted up and down without any problems, and it all seemed fine until I actually pedaled it under power while riding, and it wouldn’t downshift from the 42-tooth cog. So I cranked the B-tension screw to its limit and tried again, and it still seemed to have an issue with rolling down from the large cog while under power. I followed OneUP’s suggested trick of removing the small lock washer on the screw to gain additional length, and it then shifted properly under power. They even state that you can reverse the screw to gain more length, though I think just getting a longer one at the hardware store (4x22mm) is a better choice, and it gives you a spare backup in case you break one, which I did during my initial tweaking.

First Impressions

So how does it ride and shift? It works surprisingly well, and in direct comparison to the 32T to 36T up shift, there is a slight loss of smoothness, and a bit more of a thunk during the 19T to 15T drop due to the missing 17T; otherwise, I didn’t notice any outstanding issues. I have taken it out for several days of riding, and it shifted flawlessly, in fact; I would be hard-pressed to realize that I had this gearing installed on the bike. Although they suggest using a narrow-wide chainring, I never suffered any dropped chains during my test period with my set up. I cranked things under heavy loads on some pretty steep terrain, in both loose and smooth conditions, and the shifting and power transfer worked fine. I certainly liked not having to roll up and down through the front derailleur to get my desired gearing options, and I felt as though I could spin better with the larger chainring compared to a granny sizing.

Once I had the derailleur tuned properly and chain at the correct length, the OneUp 42T system has worked exceptional well, and I really didn’t notice any difference in usage compared to original 2×10 normal setup (11-36T rear and 24×34 front). I think this simple system, with its low-cost and fewer part swap outs will appeal to a lot of people. The $100 price, and maybe a new chain, clutch derailleur and a narrow-wide chainring will get you a pseudo alternative to the XX1/X01 wide range of gearing.

  • Wide range 1×10 gearing – XX1/X01 range
  • 1x and 2x usage
  • Low-cost and fewer part swap outs
  • Great shifting characteristics
  • Simplicity – no front derailleur
  • Weight saving for 1×10 –  depending on components used,.6 to .75 lbs
  • Missing 10T cog of XX1/X01 cassette
  • Clunky 19T to 15T shifting (due to missing 17T)
  • Might need clutch derailleur and a narrow-wide chainring (didn’t have an issue with the latter)
  • Only works with Shimano XT and XTR, SRAM X5, X7 and X9 11-36T cassettes

For more information visit https://www.oneupcomponents.com/.

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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  • 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:

    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.

  • Steve L says:

    I’ve got a couple of rides on the following setup:

    – I’m a cross country rider, ex-racer, who now doesn’t rage rocky down hills , just rides moderately challenging cross-country trails.
    – bike is an aluminum Tallboy, 100mm fork, stans wheels
    – I purchased new 10 speed x9 shifter
    – Purchased new x9 non-clutch RD at 205 grams. I first ordered a GX clutch RD and was disappointed at the weight, so returned it for the non-clutch x9 on the hunch that I really wouldn’t care.
    – I purchased a OneUp 42t rear cog and 32t oval chainring.
    – I mounted the 32t Oval chainring on my old Noir carbon cranks.
    – purchased an XTR 11×36 10 speed cassette at 250 grams.
    – And set this all up with a SRAM 10 speed hollow pin chain.

    My Experience:

    – My hunch that I would be happy with the x9 RD without a clutch was a good one. It shifts great, has a strong spring and so has very little chain slap, if any, and is about 50 grams lighter than the clutch RD’s. It’s B-screw is long enough to setup well, and it shifts great. No issues. Very happy.
    – The OneUp 42t works perfectly with the 11-36 cassette. I also installed the 16t cog to replaced the 15 and 17, and the gear spacing feels… just right.
    – On my local trails I feel I’ve given up my ultra low granny, but that’s it. On trail I never even get into the 11, so I’m not missing the high end. (my trails are pretty tight and twisty through the trees and relatively slow speeds).
    – The oval chain ring is interesting. It feels like the pedal stroke is “on” power nearly the entire stroke. While if feels like it puts the power down more smoothly and steady through the pedal stroke, I personally feel my spin is messed up. I’ve ordered a round 32t expect that will get me back to the spin feel I enjoy.
    – Overall, very please. This is an improvement and I don’t see the benefit really to 1×11. I could even go to a 30t front to better center my gearing for my trails.
    – My total cost was about $400 due to the XTR cassette over cheaper, but 100 grams heavier options.
    – highly recommend this conversion for this type of riding.

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