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I have a power2max NGeco 110mm spider with SRAM 50/34 chainrings mounted on it. I'm using an 11sp chain and an R8050 Di2 front derailleur.

When changing from the big ring down to the small ring, the chain often lands between the chainrings. The chain eventually catches the inner chainring, but until then it just slips as I pedal.

I am pretty sure these chainrings are mounted correctly (see photo below) but I noticed recently that the inner chainring has the text "SRAM 11-SPD CHAIN / 11-SPD FD YAW ONLY" printed on it. You can see this more clearly on this product page. The outer ring is a 10sp SRAM chainring.

Is this something to do with the chainring being designed specifically for SRAM's Yaw derailleur line?

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    Does it slip between or is it just skating on top of the small ring? If you look at the large ring, are the teeth offset to one side? Apr 2, 2022 at 14:04
  • @NathanKnutson I can't tell – I'm usually not in the a position to hop off the bike and taker a closer look! The teeth on the outer ring are maybe offset slightly to the inside (ignoring the ramps that put the entire chainring slightly further outboard from the spider), but the effect is very small. Apr 3, 2022 at 9:38

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Assuming the chainrings are exactly as you say, they are not a matched pair.

The 11 speed chain is made especially narrow by making the sides extremely flat with no pin protrusion. This presents a challenge for chainring designers to get a good shift as the chain isn't as "grippy" on the sides.

For this reason, all the chainring manufacturers (including aftermarket - Shimano, SRAM, Middleburn, TA, Praxis, Rene Herse, Rotor etc etc) produce chainrings in timed pairs that only allow the shift to happen in specific places around the ring and also allow the chain to be engaged with both chainrings simultaneously during the shift. This is why you will see chainring compatibilities listed such as 50/34, 52/36 but may not see 50/36 compatability if the manufacturer you are using hasn't allowed for that in their timing.

The jump on these road chainsets is large as well (16 teeth, usually) which also contributes to the shift being a difficult peice of engineering. A closer jump demands less of the drivetrain.

If you have a non-matched pair, you can end up with some strange shifting problems, and the chain bouncing off the rings on either upshift or downshift if you shift at an unfortunate moment. On 9sp and older systems, the ring timing is less critical and many people here will be used to getting away with using mismatched rings, maybe even from different manufacturers, for a long time with no problem.

Read this interesting article from Rene Herse about their 11 speed chainring development story, if you are interested in more detail.

https://www.renehersecycles.com/compass-11-speed-chainrings/

Either way, I would say to ensure you have a matched pair of rings before assuming anything else is wrong. Perhaps invest in the matching SRAM 11sp outer or buy a new matched set and sell off your existing ones to offset your costs.

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  • So if I replace the outer ring with, say, this one it should solve the problem? I get the impression from your answer and the René Herse article that my existing 10sp outer ring will not handle an 11sp chain as well as one designed specifically for an 11sp chain. Is the YAW ONLY text (only on the inner ring) likely to be an issue when using the chainrings with a Shimano groupset? Apr 3, 2022 at 9:33
  • r2-bike.com/… Is the compatible ring for your x-glide 34t inner. The Di2 derailleur is very good and should work well with these rings when adjusted properly. I have had occasions where Yaw Derailleur shifting would only work well with SRAM Yaw rings (not aftermarket rings). However, that doesn’t apply here.
    – Noise
    Apr 3, 2022 at 19:15
  • @WillVousden ok
    – Noise
    Apr 3, 2022 at 19:15
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Another possible fix - a chain catcher.

When you're shifting to the small chainring, the chain might not be landing in a way that it can engage the teeth. Adding a chain catcher might cause the chain to shift properly.

And it will provide significant protection against dropped chains that could damage your crankset and put serious gouges into your frame. And no, a properly adjusted drivetrain is not a guarantee that you won't drop your chain when you shift. Just ask Andy Schleck.

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There are other varieties available.

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  • A chain catcher is a great thing, I use one, but I don't think it will solve chain dropping between the chainrings. It acts against the chain being dropped to the bottom bracket. The biggest PIA is the chain falling below the chain catcher and then not wanting to get back. It means the chain catcher screw is a bit loose so the solution is to open it even more. As the leverage is big, the FD will stay in place. Apr 4, 2022 at 18:57

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