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On one manufacturer's website, I see the following image of a 1x chainring.

1x chainring example #1

The chainring has alternating thin-thick teeth. Here the chain's outer plates sit on the narrow (thin) teeth.

One another manufacturer's website, I see the following.

1x chainring with narrow-wide tooth profile

Here the chain's inner plates sit on the narrow (thin) teeth.

I'm assuming this has nothing to do with Shimano Deore vs SRAM Eagle.

It would appear that the first example is a mistake. The narrower width between inner plates should be mated with a narrow tooth.

Can you confirm that that is the case? At bike shops I've also seen both occurrences, and so it appears that some professional mechanics at bike factories as well as at bike shops are not familiar with the necessity of setting up this match correctly.

Update

When asking I thought that this question is a rather trivial one. It isn't.

Looking at a chainring from one side is not enough. It's necessary to look at the other side as well. Looking at one side of the chainring below, for example, would give you the impression that the front-facing groove that seems designed for seating the inner teeth would also appear as a groove on the back-facing (frame-facing) side of the chainring.

Asymmetric 1x chainrings

That's not the case. The "inner-teeth grooves" do indeed appear on the back-face, but they do not match the ones on the front side. They alternate!

The way to determine if in fact a tooth is thin or thick is to squeeze it between two fingers. If they are alternatively thin-then-thick, then it would be necessary to match the chain to them.

If alternating teeth are the same thickness, but one tooth is slightly to the left and the next one is slightly to the right (looking down while you're on the saddle), then the grooves do not indicate positioning the chain.

In the case of that third chainring, however, the teeth are not all equidistant from the spindle. They have the same thickness, but they alternate between long and short. I suspect, but really have no clue, that the long teeth should then go between the outer plates.

Sam7919
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    I think you might have just erroneously interpreted the first photo--if you look at the bottom where the chain is leaving the chainring, it is quite clear that the two are correctly mated. That does leave me wondering though, are there any chain + narrow-wide chainring combos that actually do let you use them together in the wrong pairing? I think the wide teeth are usually too wide to fit in the narrow gap at all. – MaplePanda Sep 27 '22 at 04:29
  • MaplePanda: I think you should write that as an answer, I support what you wrote. I've not seen any 1x chain that fits with narrow link on a wide tooth. The upper chainring has a bulge on the wide tooths, which gives them a visible "line", as the lower chainring has tooth that are machined to be narrower, which gives those tooth a similar "line"... – MagnusK Sep 27 '22 at 12:19
  • @MaplePanda These images might make you wonder, but here is another one (https://i.stack.imgur.com/cMq8K.jpg)—of just a chainring. That chainring is better crafted. It might even be made using a different process. In any case, the place where the inner plates "sit" is very carefully delineated. To be clear, in the two images in the question I am interpreting the lines underneath teeth as lines delineating the resting place for inner teeth, while you see them as a bulge in teeth, meant for the outer teeth. Is that right? – Sam7919 Sep 27 '22 at 15:24
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    @MaplePanda you can run a 1/8" track chain with the narrow section on the wide teeth of n/w chainring. I do not know if this works for all chainrings or just the couple that I have played around with. I suspected that some narrow/wide chainrings start life as a 1/8th track ring and have alternating teeth narrowed, but not much concrete to support this. – Noise Sep 27 '22 at 18:48
  • @Sam By "lines underneath teeth", do you mean the lines stretching from valley base to valley base? Those are present on every tooth, but their purpose alternates from one tooth to the next; they aren't strictly for only inner or only outer plates. For some chainring designs, they might not be present on every tooth anyways. The Praxis chainring you linked to has the valley-to-valley lines only on the narrow teeth. – MaplePanda Sep 28 '22 at 03:59
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    @sam the Praxis rings don't have narrow/wide teeth, they are offset so the chain will actually fit two ways. I wasn't sure how i felt about that when I first installed one. – Noise Sep 28 '22 at 12:36

1 Answers1

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You are correct in understanding that the narrow plate should match the narrow gap and thicker plate the wider gap.

Reasons why this might happen - photo shoots are often conducted by sending product to the photographer, maybe sending a marketing person along. To correct such and error requires that there is someone who is all of a) Technically capable, b) Notices, c) gives a sh.. and d) Has the authority to intervene. Even if all of the above can be met, time may preclude fixing it, or shoots taken before it was noticed make it to the editors desk. It's easy to see how a photo of an incorrectly installed chain will end up in the glossy. You as the potential customer are suppose to be looking at the sexy model and daredevil antics, not the actual bike, and the entire marketing chain is focused on those aspects.

Shops would normally be expected to have this right. Its possible an incorrectly installed chain could go unnoticed, maybe a customer 'played' with it. I would point it out to the shop and see the reaction. I would explain this happening in a shop as poor attention to detail rather than lack of knowledge - although either reason is cause for concern.

mattnz
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  • Concur - in my limited experience of 1x, the chain will not sit on the wrong teeth very well, and forcing it down results in chain suck and side plates bending or popping off. Its kinda obvious when seen IRL. – Criggie Sep 29 '22 at 01:07