1x, 2x, 3x chainring - does it matter?

Question

I need to replace one chainring in my 3x9 setup. One possible option I'm looking at says it was made for 2x setups. Another option says it was made for 1x. They have the correct tooth count, BCD, and bolt layout. How much does this matter if the manufacturer says it was made for 2x or 1x setup? Am I going to run into problems using a chainring that was "made for" a 2x system on my 3x9 system?
(this is a follow-up to an earlier question: Does "speed" of a replacement chainring matter?)

whatsisname · Accepted Answer

Chainrings designed for multispeed systems have special pins and ramps in them, to assist shifting. Key word being assist. If you have rings for a certain config, it might not have those features in the right spots.
If you don't have them, shifting won't be as good as it would be otherwise. That doesn't necessarily mean it'll be complete garbage either, people happily rode bikes with "plain" chainrings for decades, and continue to do so today. But it won't be as crisp, or you won't shift as well under power, but you'll almost surely shift well enough.

Criggie · Answer

Additionally, a 1x chainring is likely to be "narrow-wide" to help with chain retention.
If you look closely, every tooth is alternately wider and narrower, so you place the chain on such that outside plates are around a wide tooth.
If you had used a FD to change chainrings, there's a 50% chance the chain will land wrong, and your wide tooth gets wedged inbetween two inner plates.  This would stop the chain leaving the tooth at the bottom of the rotation, (chainsuck) and potentially could pop the side plates off the chain (unlikely but not impossible)
So a narrow-wide chainring will work very poorly on a multi-chainring setup.

MagnusK · Answer

More additional information for 1x setup:
Besides bolt layout matches and tooth-count, on 1x there is an additional parameter: offset.
The chain-ring offset from the crank helps the chain get a good line towards the cassette on the rear hub. The chainline will differ on a bike frame with boost rear spacing and non-boost spacing, so there are different offsets on chain rings or spacers to get a correct chainline.
Chain line is explained a bit more here:
https://www.oneupcomponents.com/pages/understanding-chainline-for-optimal-1x-conversions-boost-and-non-boost
On a 3x setup, the chain rings will probably not have different options for offset.

1x, 2x, 3x chainring - does it matter?

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