Have you checked the limit screws?

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the world's still turning? >>>>>>> the world's still turning

Maybe a dumb question. But if i adjust the limit screw won’t the chain still move inwards under load but instead of falling off it would rub the derailer instead?

I guess I should try that first, but trying to figure out how why it’s happening

How worn/old is the front small ring?

Classic mistake is that chainring is on backwards. May not matter for some chainrings though.

I’m using SRAM force 22. Pretty sure my rings don’t come off

Groupset is 4 years old, approx 35k miles

Chainrings don’t look bad

I have had similar issues recently but with my big ring. My chain was stretched so I replaced it which made the issue better but not completely fixed. I was still getting slippage any time I got out of saddle and sprinted. My big chain ring did not look worn but I had a spare crank laying around so I swapped it real fast (easier to swap cranks than chain rings) while doing a trainer workout and the problem went away.

A few weeks later and day before a race, I put on a new race chain. New chain caused some slippage when sprinting out of the saddle. Noticed the chain was quite stiff. So I went back to my previous chain (still relatively new) and had no issues on race day.

I would just replace the chain ring. More than anything just to rule it out.

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blog

How did you measure the chain wear?
Have you pulled a new chain around both your cluster and the ring to see how well it engages?
With the new test chain draped over the rear cluster in your most used gear and pulled hard does it want to ride up the teeth or stay seated deep in the teeth?
With the new chain draped over the front ring and pulled hard does it try to ride up the teeth? (remember to pull the other direction to the cluster test)
When in the easiest gear does the front derailleur just clear the chain by .5mm?
Are your chainrings round or elliptical.
Chains falling off the front like you say is usually the first sign the chain is cactus.

I have round rings.

No on clearance - that should be more of a big ring thing, right?

I simply measured the chain using the park tools chain checker. It’s always lubed properly and rear cassette is in good shape.

Perhaps I should just try a new chain. This one could have 8k miles on, but 95% of it is ok trainer in the garage. Figured I’d get longer life

Good idea. This will be next thing I try

I only have an old SRAM compact crank laying around so I was hoping to try and address issue on this one... since even if it works ok on compact I still need the 53/39 to work properly!

What is the reading on the Park chain checker?
11 speed needs new chain not long after reading .5.
If you let it go past half way between .5 and .75 then you are very quickly trashing your cluster.

I’m not quite to .5 yet. The tip of the tool is into the chain but not fully suppressed.

Things to looks at:
Check inner ring is good
Check chain really is good
Front mech cage bent
Front mech alignment
Front mech gap to rings
Inner limit screw.

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Developing aero, fit and other fun stuff at Red is Faster

Check front derailleur adjustment https://www.parktool.com/...erailleur-adjustment. You could also install a chain catcher for good measure.

This thread might be helpful:

https://forum.slowtwitch.com/...20your%201x#p5752620

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Oui, mais pas de femme toute de suite (yes, but I am not ready for a woman straight away) -Stephen Roche's reply when asked whether he was okay after collapsing at the finish in the La Plagne stage of the 1987 Tour

It's too hilly in austin to ride 1x.

I've never been to Austin, so I am not able to comment as to the difficulty of the terrain. But, I have done IM Canada and IM CDA with a 1x setup and never felt I needed more gears. Not sure if Austin is hillier than the Canadian Rockies. Maybe your comment was supposed to be in pink.

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Oui, mais pas de femme toute de suite (yes, but I am not ready for a woman straight away) -Stephen Roche's reply when asked whether he was okay after collapsing at the finish in the La Plagne stage of the 1987 Tour

Lots of 8-10% hills, but short. Most rides I get 1000 feet of climbing per hour

For those hills I’m often in 34/28 wishing for another gear or two

Don’t always need top end gears but they are helpful on the decents

Don’t believe 1x in this terrain is optimal. But suppose I could look at an 11-32 to open things up more...

Still not what I’m after at the moment

This is helpful checklist.

Though, Wouldn’t most of those not apply (outside of chainring/chain) since the bike shifts perfect and chain just slips when under load?

What kind of crankset do you have? Any chance crankset flex under load could be a factor? I had a very flexy FSA Omega on my bike that would drop the chain if shifting under load. (Not exactly the same as yours, but maybe in the same family). Anyway, it got better wheth a better crankset.

Edit: never mind. I saw your post that said you are using Force 22. Those are awesome cranks.

True but this is edge condition. A correctly set up mech will still be less likely to ship the chain.

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Developing aero, fit and other fun stuff at Red is Faster

It’s a Sram force crankset. I’ve used it on other bikes with no issue

It’s hard to figure out why it’s happening because it rides okay without being near max effort. So i can’t “see” the issue

Bought a new chain so will see how it goes, then I’ll buy a new ring (looks like i can replace the force 22 rings?) Then I’ll buy a new crank

Maybe the crank isn't flexing but any chance the BB, BB shell, etc. is flexing? With it only being during max effort it sure seems like flex is coming into play.

Yes, and I also had a weird issue once, pretty much identical as the OP except my problem was a wrecked bb
Ultegra bb cups that had shredded the DS bearings so that the crank rocked when you pedalled. Never noticed it, but I would always drop the chain on the small ring trying to hammer up one particular climb.
Switched to DA bb cups and everything was fine (till I stripped out the threads on the bb shell, but thats another story of a bike manufacturer not honouring their "lifetime" warranty)