Chainring is over rotating the chain.

[Myles_mtb]

I have a specialised terbo levo sl. I have just changed the cassette [12 speed] and derailleur to [GX axs] and chain [KMC]. I have now just changed the chainring as it was warn as well. It’s now a renthal 94bcd sram narrow wide chainring.

Since changing the chainring, it seems to over rotate the chain when been peddled in any gear, as if the chain is getting stuck in the teeth of the ring.

Any suggestion are appropriate

 

[onehundredthidiot]

Chain suck is usually a sign of a worn chainring.
Have you got a narrow wide chainring and an incompatible chain? Personally I'd used a SRAM chain on that set up.

 

[Zimmerframe]

Sounds like you have the chain one tooth out of sync for the narrow wide ?

 

[onehundredthidiot]

There is that. Is the chain sitting snug in the chainring or does it sit proud of the lowest points? If it's not really snug then lift it off and turn the chainring slightly. The chain should easily drop onto the chainring.

 

[RustyIron]

Sounds like you have the chain one tooth out of sync for the narrow wide ?

Unsync'ed teeth? It's that for real?

 

[Zimmerframe]

Unsync'ed teeth? It's that for real?

On the chainring, if it's a narrow wide, then yes.

The chain has alternating narrow and wide gaps in the links.

If it's a narrow wide ring, then the teeth will alternate narrow wide.

If you have the narrow links on the wide teeth, the chain will sit high.

 

[onehundredthidiot]

If it's off usually the chain will sit high on the teeth. (By off I mean the narrow wide doesn't fit with the chain narrow wide). There will be a visible gap between the trough between teeth and the chain. If it all sits snug change for a SRAM chain.

 

[Spangoolies]

Also is it definitely a 12spd chainring? If it’s not then it will be too wide for any 12spd chain and the chain will hang up on it

 

[Paulquattro]

Also is it definitely a 12spd chainring? If it’s not then it will be too wide for any 12spd chain and the chain will hang up on it

Chains from 9 to 12 speeds have the same inner width its only plate thickness that differs 12spd being the thinnest so there shouldnt be no issue there
Its more likely as already said out of sync or he has a faulty component chain or sprocket .

 

[Spangoolies]

Chains from 9 to 12 speeds have the same inner width its only plate thickness that differs 12spd being the thinnest so there shouldnt be no issue there
It’s more likely as already said out of sync or he has a faulty component chain or sprocket .

That’s todays new thing learned!

 

[Paulquattro]

That’s todays new thing learned!

A day is wasted if we don't learn something

 

[kombos]

Examples….

 

[Rod B.]

I have a specialised terbo levo sl. I have just changed the cassette [12 speed] and derailleur to [GX axs] and chain [KMC]. I have now just changed the chainring as it was warn as well. It’s now a renthal 94bcd sram narrow wide chainring.

Since changing the chainring, it seems to over rotate the chain when been peddled in any gear, as if the chain is getting stuck in the teeth of the ring.

Any suggestion are appropriate

Myles,

Some modern 12 speed chains are directional. This is due to one edge of the chain plate having Asymmetrical chamfering which facilitate easier and quicker shifting. SRAM 12 speed chains are not directional, whereas Shimano 12 speed chains are directional. Some chain quick connect links are directional, while others are not. Some chain manufacturers, i.e. KMC, make chains which are compatible with most drivetrains and are non-directional. However, KMC states that it's X2 series of 12 speed chain has Asymmetrical chamfering on the chain plates.

It's important to know If a chain or quick link is directional. If a directional chain or quick link is installed backwards, i.e. upside down, you may encounter issues with poor or noisy shifting at the rear derailleur, or the chain not releasing from the chain ring as it rotates, known as "Chain Suck."

Your issue may possibly be a conflict between the Renthal chain ring and the KMC chain. The Renthal chain ring that you purchased has a SRAM tooth pattern. It may not work with KMC. For shits and giggles, I would try flipping the KMC chain and quick link to see if it's possibly a directional thing. If that doesn't help, I would replace the KMC chain with a SRAM chain.

All bicycles have an optimal centering of the chain ring with the cassette. This allows the chain to move freely up or down the cassette without binding at an extreme angle when the chain is shifted to a high or low cassette cog. If the chain line is incorrect, you may encounter a "Cross chaining" situation in which the binding is also affecting the release of the chain off the front chain ring.

I mention the above because my Levo comes stock with a 104 BCD pattern chain ring and chain ring spider. You purchased a 94 BCD Renthal chain ring for your Levo. Did you also purchase a 94 BCD chain ring spider? If you did purchase a spider, does it have the correct offset? If an incorrect offset is installed, it will position the chain ring too far to the right of left and your chain line will be off. This can cause a chain binding issue which can affect the release of the chain off of the front chain ring. I think this idea is a long shot, but maybe it's something to check out.

Let us know what you come up with.

Be safe,
Rod