OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

When SRAM first introduced their 11-speed Red22 group, they made a big deal about it having a 16t cog in the mix. Sure, it was tongue in cheek, but indeed, 16 seems to be the magic number now that oversized large cog cassette adapters are all the rage. Fortunately, you don’t need to pull apart a perfectly good road cassette to get your 16-tooth fix.

OneUp Components has just introduced a 16-tooth cog to slot in between the 13 and 19, smoothing out the jump to just three teeth on either side. It replaces both the 15 and 17 when adding their (or any other) oversized 40t or 42t large cog. The result is an even transition at the smaller end of the cassette, eliminating any 4-tooth gap.

We mated it and their new 40t cog to an XTR 10-speed cassette. Tech details, weights and first impressions below…

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

OneUp’s 16T sprocket is machined from chrome plated hardened steel, in contrast to the 7075-T6 alloy of their large cogs. But, it shares the SRAM-or-Shimano compatibility of the big ones, using different clocking positions depending on the brand. If you were to get the whole kit and caboodle, you’d receive the above items. The spacer is for placing the 40/42t cog behind a SRAM cassette. It’s unused on a Shimano set up.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Claimed weight for the 16t cog is 18g, exactly what ours came in at. Spacer is 2g and 40t cog is 69g. Zach’s also been testing their 42t cog, and you can check out his first impressions here. Most of what follows is about the 16t cog.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Engraved on the cog are clocking sync points for SRAM and Shimano. Shown above, the “SH” is for Shimano and indicates the position of the cog that should be slid over the wide gap on the freehub body. Place the “SR” there for SRAM cassettes. This lines up the ramps and teeth for optimum shifting. As it turned out, I didn’t have these instructions when first installing and just slipped the non-notched space on the cog over the thinner freehub spline and went riding. Shifting was decent but not stellar…until I lined up the dots as they should be. From then on, shifting to and from OneUp’s cog in either direction was as smooth as the rest of the cassette. Impressive.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Definitely a visible difference in spacing, but not as obnoxious as a 4-tooth gap.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Here’s what the cassette looked like in standard trim on the left, and with their two replacement cogs on the right.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Just for fun, here’s what it looks like ramped all the way up on the 36t (left) and 40t (right). My b-screw was buried to get it to shift off the 40t, definitely need to add a longer screw just to be safe. In the large chainring (not that I’d ever cross chain like that) it wouldn’t shift off the 40t cog until I downshifted the front. A longer b-screw should remedy that.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

On the trail, I spent the first 20 minutes paying careful attention to which cog I was in so I knew when I was shifting in and out of the 16t. After that, I all but forgot about it, only glancing down once in a while just to see where things were. That’s good news. It shifts so well and keeps the transitions so close to normal that it’s eventually forgotten about. And that’s what any good component should do – work so well you forget it’s there.

OneUp Components 16t replacement cog for cassette upgrades to oversized large cogs

Yes, I could tell when I was going on or off the 16t if I was really thinking about it, but under normal riding, the 3-tooth jumps aren’t that big a deal. Anyone who’s already added an oversized upper cog should give this a good look.

I spent minimal time in the large cog simply because our local trails aren’t that steep. But, I can already tell I’m gonna love it when I head to the mountains. Shifting in and out of it was also pretty smooth, with only a little hesitation coming off it until I slammed the b-screw into the derailleur.

The 40t cog retails for $90 and should be back in stock April 11 (preorders being taken now), with free shipping worldwide. The 16t goes for just $15 plus shipping and should be available to ship Monday, April 7th in early May. But, order a new 42t or 40t cog and you get the 16t free. Effin’ sweet.


  1. “they made a big deal about it having a 16t cog in the mix. Sure, it was tongue in cheek”
    Really? I think it is a big deal and why I won’t use the Shimano 11-28 cassette.

  2. With x01 cassette you also need a new freehub, new derailleur, new shifter. Personally, I prefer Shimano shifters and derailleurs – by a lot.

  3. If buying a full high-end drivetrain and you’re looking for a wide range 1x setup, going SRAM 1×11 makes sense. But this is a much cheaper way to upgrade your existing 10 speed drivetrain. What is there not to get?

  4. I have X01 and frankly would PREFER a good Shimano extended range setup like this. To me, SRAM shifting is like remote control – in a bad way – click a button and something moves at the back. With Shimano you really feel the connection between the shifter and derailleur – I think that feedback is noted in this review.

  5. I’m sure it’ll work better than a 15 or 17 tooth cog. But would someone PLEASE make a 10-speed cassette with a 40/42 tooth cog you dont have to sell a kidney for. These modpacks are getting ridicilous.

  6. It makes no sense to compare the number of teeth in gear changes at different points of the cassette. What matters is the RELATIVE change, in percent, because that’s the difference you feel. A 13-15 (2t) change is 13%, and feels about the same as 28-32 (4t) which is also 13%.

    This 16t cog is the best compromise for this cassette hack, but still gives a strange shifting sequence. The first 4 shifts from the smallest cog are 15% – 19% – 16% – 10%, where the original has 15% – 13% – 12% – 11%. (The jumbo jump from 36 to 42t is merely 14%, as is the 24-28t shift, so that’s quite normal.)

    Still, I have use for this on one bike and I’d buy it right now if they sold it in 9-speed. (Buying a 10-speed gripshift is at the moment a bit overkill for that ride.)

  7. Just did a 42T conversion on an XT 11/36 cassette for a customer and it shifts like crap going up without the 17, hope the 16 fixes that jump.

  8. @Gunnstein – Not sure how you got those numbers. It’s pretty simple math. 36t to 42t is a 12.5% jump. For the rest at the low end:
    11-13-15-17-19 (original)= 18%-13%-15%-12%
    11-13-15-19-21 (w/o 17t)= 18%-15%-27%-11%
    11-13-16-19-21 (w/16t)= 18%-23%-19%-11%

    I’d take he 16t setup if it shifts well as the big jumps in the 11-16 range when you’re really cruising that fast are easier to handle. The 15-19 jump is just plain silly.

  9. @MB: Yes, it’s pretty simple. Don’t know how you got your numbers 🙂 But it looks like one of us is counting the upshifts and the other the downshifts. Same thing, different value.

  10. @MB Looks like there is a glitch in your 11-13-15-17-19 (original) sequence, the percentages should decrease steadily since all gaps are 2t while the count increases.

  11. I have a 1X10 setup with a Wolftooth 42T in the back and a RF 30T N/W in the front. I took out the 17T and have the 15T to 19T gap. Mine shifts fine and I love the setup.

    I thought about getting a 16T but I don’t think it will help like everyone is thinking.
    Yes the 16T will make an even 3 tooth jump from 13T-16T-19T and it lowers the percentage from the 15T-19T from 27% to 19%.
    The problem I see is it also increases the 13T-15T to 13T to 16T and the gap from 15% to 23%. I think the 23% jump on the 13T-16T would be more noticeable than the 27% on the 15T-19T since the 13T is so much smaller.
    11-13-15-17-19 (original)= 18%-15%-13%-12%
    11-13-15-19-21 (w/o 17t)= 18%-15%-27%-11%
    11-13-16-19-21 (w/16t)= 18%-23%-19%-11%

  12. I did the 42T upgrade. Love it. The only time I notice the jump is pedaling on the road to the trailhead. Otherwise not noticed. Great upgrade. Im running it as a 2×10 24/34 up front.

  13. I just upgraded two of my bikes this week with the OneUp 40T. I upgraded my XT and SLX cassettes. I love that extra little grunt that I have now. Helped me climb a couple of tech sections that I hadn’t cleared in awhile. Of course, when you’re climbing you don’t miss the 17T but when you’re rippin down the fire road you feel the jump from 15t to 19T. I’ve got a couple of old road and mtb cassettes laying around. Im going to check if they have 16T cogs before I go buy another fancy Al cog.
    About the only negative I had was having to purchase new chains for my 1×10 setup. The chain was too short to work with the 40T on both bikes. I didn’t have any leftover chain links so had to buy two new chains.

  14. Just installed a One-Up 42T on my 11-36 XTR cassette. I’m kinda surprised everyone is focused on 16T issue and nobody is even mentioning the possible degraded shifting experience from maxing out (or replacing with a longer) the b-tension screw. I’m currently running a XTR long cage rear derailleur. I did not have to use a longer b-tension screw. I simply max’d out the stock screw. Shifting in the bigger cogs is fine, but when I’m in the smallest cogs, where the derailleur is now furthest away from the cassette (due to excessive b-tension), the chain has a slight tendency to jump. Not sure if others are facing this issue, but it makes sense that shifting will be a little more sloppy towards the bottom of the cassette since the derailleur is now farther away from the cogs. Looking forward to what Shimano might debut SeaOtter!

  15. @Jason
    This was one my motivations for considering going to a capreo hub instead of a conversion cog, as well as the increased clearance from going to a 28t front. Logistically, between the new hub and cassette, and cranks that will support a 28t, it’s far more expensive. In the end, I haven’t done anything yet, because I’m not convinced that I need more than 32×36 on my bike, due to geometry not being real climb friendly.

  16. Looking at the picture, I do not understand how the shifting from 16t to 19t can be considered proper even though it may be working. Even when putting the “SH” logo into the bigger slot, the ramp is not aligned properly against the other cassette cogs’ ramps. There is a relief tooth and a catch-on tooth on the 19t cog to “catch” the chain when up-shifting from 16t.
    From the picture, it will look correct if the ramp of the oneup 16t is rotated clockwise another 45~50degree.

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