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I recently switched my SRAM 1x12 Eagle SX drivetrain from a 30 to 34 direct mount Chainring. I also bought a new chain to accompany with it. Chain length was measured as the sram service manual advices. Put the chain around the largest rings and have 4 links overlapping.

The cassette has around 700km.The previous chain had around 0.5% procent wear.

When going into the highest gear and one cog beneath it by chain slips when applying pressure. The other gears work fine.

I degreased the new chain upon arrival since it was very sticky and applied dry lube after washing off the degreaser and drying using a towel.

I read online and some advice the cassette need to be replaced but after 700km to me that would be really strange. Could the chain slippen have something to do with the derailleur height? Which might be different since my chainring has chained or is this not correct?

I assume a larger chainring does not have impact on the left/right adjustments of the derailleur?

Another option I was thinking about was wiping as much dry lube of the chain applying wet lube. enter image description here enter image description here enter image description here enter image description here

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    A picture of the whole drivetrain and of the cassette teeth might help.
    – Vladimir F Героям слава
    Commented Sep 25, 2020 at 9:33
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    Nothing you've described sounds like a cause for chain slip. A picture might show if the chain seems too long, and therefore not enough tension though larger cogs should be fine and that would cause issues with smaller ones.
    – Criggie ♦
    Commented Sep 25, 2020 at 9:40
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    Probably the chain it too long.
    – Daniel R Hicks
    Commented Sep 25, 2020 at 11:33
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    Shift into your lowest gear and see if there is enough slack to take out a full link.
    – Noah Sutherland
    Commented Sep 25, 2020 at 17:04
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    @Christoph See how the part of the teeth contacting the chain (the left hand side of each tooth) look like they’ve been smushed over? It’s most noticeable on cogs 10 and 11. To be blunt, the quality of the SX groupset is pretty bad across the board, and I could rant about it much like how a certain user rants about non-Shimano hubs. The fact that SRAM gives a hefty discount if a manufacturer specs RockShox suspension AND a SRAM drivetrain means that SX gets specced quite often.
    – MaplePanda
    Commented Sep 26, 2020 at 2:39

3 Answers 3

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You can play around with chain-wrap and cable adjustment all you want but this problem is 99.999% of the time caused by wear on the cog's teeth. Ask your LBS if they can sell you only the cogs you need. It may seem like the cassette isn't old enough to justify being worn out, but that's a 10 tooth cog you're talking about, a tiny piece of thin metal responsible for handling all those watts we put down! ;) Plus, considering you made the switch to a larger chainring, I get the impression that you were doing a considerable amount of riding in your highest gear, accelerating the wear it experienced.

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  • I also hate that tacky factory protective coating on chains! I wouldn't consider it entirely necessary to remove, though, fwiw. You risk stripping off the good lubricant that is deep inside the rollers and bushings, which can be hard to replace.
    – Nathaniel Hoyt
    Commented Sep 25, 2020 at 23:50
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    Minor nitpick - SX only goes down to an 11 tooth cog. GX and higher use the XD driver, allowing them to have a 10 or even 9 tooth.
    – MaplePanda
    Commented Sep 26, 2020 at 2:34
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    thanks @MaplePanda i've always been bad about groupset specifics
    – Nathaniel Hoyt
    Commented Sep 27, 2020 at 19:57
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    I placed a new NX cassette and the skipping stopped. This proves the cassette was definitely worn. Hopefully the switch from pg-1210 to pg-1230 is a bit more durable this in combination with my chain running a bit straighter with the 34 tooth chainring.
    – Christoph
    Commented Sep 28, 2020 at 12:54
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Maybe not relevant or too late for you but this may help someone else....

I had the same issue with chain slipping on smallest two cogs of the Eagle cassette when applying pressure .

Tried mostly everything everyone has suggested on this forum to tune the gears....

And then I realised all it was is that I installed the sram powerlink on the chain the wrong way around. The directional arrow on the link must point the same way as chain direction when pedalling.

Flipped it around and issue resolved.

Felt stupid but it reminded me that sometimes I consider complicated possibilities before eliminating the basics.

Amo weekend mechanic.

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    +1 on installing the powerink the wrong way round. Took me ages to figure it out. one edge of the powerink plates is straight - that straight edge needs to go on the outside.
    – rickybails
    Commented Mar 7, 2021 at 18:00
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I have also had this problem several times. Both methods were needed for my road bike after I took a tumble. I have found that it could be caused by a few different things:

  1. Could be a very slightly bent derailleur hanger

How to fix it:

You can try to fix this by bending it back but be warned! Most derailleur hangers are aluminum and break/snap very easily!

  1. It also could be a minor limit screw adjustment

How to fix it:

Try undoing the limit screw one quarter of a turn at a time till it shifts smoothly. Make sure there’s not too much tension in the cable as to prevent the derailleur from reaching its limit screw

Hope this helps!

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