OneUp 42 Tooth Cog: Hands On

Installing the 42 Tooth Pie Plate

Words by Jonathan Harris. Photos by Jonathan Harris. Video by . Posted by
January 22nd, 2014

My knees just breathed a sigh of relief. My OneUp Components 42 tooth cog arrived and is now mounted up on my bike. Having jumped on the 1x trend back in the summer I have been working with the 30 tooth Wolftooth chainring matched with my Shimano 11 to 36 tooth cassette.


42 tooth gearing on the back of my 10-speed drivetrain? Sign me up!

In most scenarios the ratios on offer work very well for me, however there are those few climbs where having a slightly lower gear would be nice. It would allow me to finesse up a climb rather than grunt. So without ripping out my Shimano drive train and dropping some serious coin on XX1 when I heard about the OneUp Components 42 tooth option my hand shot up first, especially when you consider that the OneUp option is $100 and not $1400+.

The cog is machined out of aluminum, with shift ramps machined into the tooth profile. The cog has a wide interface with the freehub which makes me hopeful that it won’t chew up the carrier like some individual steel cogs can. It also has some raised nubs, which initially look arbitrary but once installed actually butt up to the 36 tooth cog to provide some stiffness.

The OneUp Cog in all its green anodized glory (also available in black). The cog has shift ramps machined into the profile to help make the jump from the 36 tooth cog, along with some platforms to butt up against the rest of the cassette.

Fitting the cog is really very quick. It actually took my longer to find my chain whip than it did to get this fitted and set up. Firstly my current set up is a Shimano 11-36 tooth cassette, XT rear derailleur and a Wolf Tooth 30 tooth front chainring all mounted up to my Santa Cruz Tallboy LTC.


The before shot. This set up has been on the bike since June.


The XT cassette removed and dismantled with the 17t cog about to be relegated to the parts bin.


Depending on your cassette there is a spacer that needs to be placed either behind or in front of the OneUp sprocket. I have a Shimano cassette so it is fitted behind the cog and hidden in this photo.


Then put the rest of your cassette on, remembering to leave out the 17 tooth sprocket and spacer.

Tighten up the lock ring and that is it, the sprocket is installed. With the larger range of gears I needed to add a couple of links to the chain. Luckily I had some still after I had recently installed my new chain.
Before you reinstall the wheel make sure to adjust the B-tension screw. This is important to ensure that the cage of the derailleur will clear the larger sprocket. On some frames with Shimano rear derailleur’s the B-tension screw may not be long enough to get the cage to clear the cog, which was the case on my bike. After consulting the instructions on the OneUp website I followed the suggested remedy of removing the B-screw, removing the plastic washer that remains attached to the screw and reinstalling the screw without this washer.  There are good instructions on the OneUp Website to help you get it working well with your specific setup.

Now reinstall the wheel and away you go. Check the shifting, particularly between the 36 and 42 tooth cogs and check the high limit screw. Mine was just fine and the bike shifted fine in the stand. The whole installation is quite straight forward and takes maybe 20 minutes to complete (after finding your chain whip).


The after shot with the OneUp installed and derailleur set up to clear the new larger cog.

To give the new setup a good workout I took the bike for a loop on Seymour, one that has lots of shifting. First impressions are good. The shift up to the 42 tooth cog is surprisingly crisp, especially considering that the derailleur was never designed to shift to such a large cog. Given that the shift up is usually one that is done under pressure, none of my shifts up to the OneUp cog were met with any more noise or hesitation than any other shift around the cassette. The jump lower down the cassette from the 15 to 19 tooth cog is noticeable. To be honest I didn’t use those gears once I was into the trail system, so in normal riding it isn’t an issue. For a lot of the riding around here you are typically stuck in the top 2/3rds of your ratios. If you are someone that rides in an area where you use every ratio on your cassette this may be an issue. There is a lot of discussion on the forums that there is a way to bridge this gap with some cogs from other cassettes if it bothers you enough.

So far the OneUp seems like a good solution for those of us that want to run a single ring up front but still want a gear to climb in without blowing our knees out. There are some things that I want to keep an eye on over the next few months. I’m intrigued to see how the cog wears in the wintery conditions and if the single cog in such a high torque situation causes any damage to the freehub body. I’m also interested to see how my Shimano XT rear derailleur stands up to being stretched over such a big range.

OneUp Components has been nice enough to extend the $15 discount for NSMB readers mentioned in the initial article. Simply use the discount “nsmboneup” and it is good until midnight Saturday, January 25th. Pretty sweet!

  • shoreboy

    Discount code is no longer valid, you might want to remove that from the article. I used in the subject line and got an autoreply message:

    “Unfortunately due to such high demand for our 42T Sprocket we are no longer offering this discount code.”

    • morgman

      Updated the article with a new discount code – see below.

  • GladePlayboy

    Still a good deal even without the discount code. The one installed on my fat bike has been flawless. Such a seemingly small upgrade for a big improvement in performance. Have another one on the way for my Carbine…

  • Bradical

    Good article, now if only it was March…thats when mine should arrive, they are 2 months out on orders….Big demand

  • boot

    I find it really hard to believe that Shimano hasn’t offered up at least an 11-40 ten speed cassette??

  • morgman

    Hey guys, we’ve just heard back from OneUp and they are indeed honouring the discount. Good until this Saturday, January 25th, use discount code “nsmboneup” on checkout.

  • semaj

    Shouldn’t the spacer be on the front side of the OneUP ring if using a Shimano cassette? That’s what is printed on the ring itself, but the picture caption says he has it hidden behind the ring?

    • OneUp

      Hi Semaj, the sprocket shown in this article was a pre-production sample that had incorrect laser on the front side. Production rings have corrected laser instructions.

      • semaj

        Awesome, thanks for clarifying! I ordered one today in black 🙂

  • bogey

    @semaj, I saw that too. Jonathan, what’s the deal with your incorrect installation?

    • morgman

      OneUp printed the SHIMANO word on both sides on these samples. It is installed correctly. Spacer behind for Shimano, spacer in front on SRAM, as per OneUp’s instruction sheet.

      • Jon-boy

        Thanks for having my back Morgan! 😉 I did indeed follow the correct instructions, sorry for the confusion.

  • shoreboy

    Ive sent an e-mail to OneUp asking if they can correct their checkout and not charge us BC folks the PST. I will let you know what I hear!

    • shoreboy

      OneUp got back to me and say they have corrected the PST problem on their website. The two rings I ordered confirmed this.
      Order away!

  • GladePlayboy

    I asked them about the PST back in November when I placed my order and they never got back to me with an explanation.

  • slynx

    Anyone else think it might be a good idea for Oneup to also sell a 16 tooth cog? Hell, make it green.
    I would buy it with my 42 tooth order.

    • Be Prime

      I know this comment is old, but one up took your advice, they supply you with a free 16 tooth cog now when you order the gear.

  • megrim

    When I first saw the article for the OneUp, I ordered one right away, but not really knowing which bike I would put it on (Carbine or Podium). Both bikes are built to pedal (sort of) and descend. When it showed up, I ended up putting it on the Podium. Wow, this was really easy to install. I had a Zee short cage derailleur already on the Podium, so I decided to give it a go (not recommended by OneUp). I dialled the B-tension screw all the way in and added 2 pairs of links to the chain. The shifting was perfect for gears 1 through 7, but the chain seemed to get caught on the derailleur on the odd shift between 7 and 8. Also, probably due to the B-tension addition, shifting from 7 to 8 would end up going 7 to 9, then back to 8. Because of this issue (and I rarely get to 8th or 9th on the shore), I pulled the cassette apart. I put the 17t ring back and removed the 15t. It ends up being a very big jump, but I’ve got a great gear range 1 through 8.

    I’ve taking the bike for a couple rides now and I am blown away how seamlessly it shifts. This 42t cog was definitely welcome on those long grinds (the Old Buck) and a few techy uphill sections.

    Overall, I would really recommend this 42t cog.


    • boot

      Hey Mike thanks for that info, I was also going to try a short cage. So do you forfeit the smallest ring/rings, or does it actually take up teh slack(with poor shifting you mentioned)?

      I’ve tried med and long XT rear mechs but they just don’t last. That extra bit of length seems to put them in a high risk danger zone.

      • megrim

        @boot – I can still shift into the smallest cogs, but it’s not the best shifting. Although, the shifting into those cogs before wasn’t the best, so take this with a grain of salt. I’ve only been able to use 10th when I have a brand new setup (frame, wheel, derailleur, etc.), otherwise all my bikes never see 10th. So for me, this really isn’t an issue.

        At first, I put on a long cage derailleur as per the instructions. But since the Podium doesn’t seem to have a bunch of chain growth, I didn’t think I needed it. But with either derailleur, I could still get down to the smallest cogs (actually a little better with the short cage).

        If you have a bike design with a lot of chain growth (VPP, etc), then I would go for the medium cage derailleur. There’s no way a short cage with the 42t cog would have worked on my Carbine.

        Hope this helps.


  • Da Peach

    Any word if one of our local outfits might be making a version of this? (NSB, RaceRace, etc…)

  • Jonathan Harris

    So I was asked to give an update on how my cog is running 6 months in… Well I think it speaks for itself that the cog is still on the bike. I don’t see it going anywhere especially since bringing the shift quality back to how it should be with the Rad cage. I rode a lot this winter and I can’t estimate the mileage I have covered, but let’s say I have averaged 2 to 3 rides a week including taking my bike to NZ and Australia to ride. Wear on the teeth of the cog seems normal. I am about to give the bike a bit of TLC and will remove the cassette to see how things are fairing, especially since the free hub needs to see some grease. More to come.