pbass

My 2019 Kona Rove ST has a SRAM Rival 1, 1x11 setup that typically performs flawlessly. Yesterday on a ride I was shifting up fast and hard approaching a descent and didn't realize I had gotten to my smallest cog and tried to shift one more--hit it kinda hard, standing up, lotsa weight on the pedal, jamming that shift lever in, bad timing I could tell, and the chain came off on the outside of the smallest cog and got stuck. Bike kept going but pedals stopped. I put the chain back on the rear and rode home with no issues, shifting as smoothly as ever.
Everything seems set up properly as I examine it. The RD hasn't taken any hits or anything like that. In fact it was just at my LBS recently and they went over it all after doing some other stuff for me. Shifts like a champ on my stand, and as i say the ride home was totally normal.
As I say it was a crappy, very un-smooth shift on my part, but should one expect the high limit setting to totally prevent such a phenomenon? Or can you hit it just wrong on a properly dialed in bike and pop that sucker off like that, even with things set up to spec?

Retro Grouch 

I'd try about 1/4 turn on the high limit screw.

hokiefyd 

The way I read your post, your shifter allowed another shift down off the smallest sprocket. If you were already in the smallest sprocket, you shouldn't have had "another click" on the shifter, no matter how hard you tried to get it to shift, right? A flat bar shifter would have felt "dead"...as in no more ratchet clicks. Do drop bar shifters work differently?

If that IS the case, and the shifter really did click again or allow another shift, allowing some more cable slack, then I'd probably start with getting the shifter adjusted and indexed correctly to the cassette, if it's not already.

In either case, it would still seem that tightening the high limit screw just a bit would help keep the chain up on the smallest sprocket. If you look at the derailleur from the rear, it should be exactly centered under the smallest sprocket when in the most outboard position. Much in the way of a right shift from center could allow the behavior you describe. Because it's a steel frame, and possibly a little more flexible than average, maybe the frame just twisted a slight bit during the stand-up pedal...a more aggressive high limit screw adjustment (to where the chain will just barely fall down onto the smallest sprocket) may be needed in your case.

pbass

Thanks folks! I can't say I actually recall a "click" in the shifter when it happened, but now I'm not sure. As I say, it was a awkward, clunky move on my part--I was really jamming down on that sucker, shifting at a bad place on the pedal stroke, etc.
I got on it again this morning and tried to recreate the event and couldn't do it. But I don't think I was totally reenacting the sloppiness of my performance this time I will try the adjustment of the high limit screw and see how things go.

CliffordK

I'm surprised there is space for the chain to fall off to the right.

I don't think any of my current bikes have enough space for the chain to fall between the sprocket and the stays.

Any way to remove a spacer on the right side of the axle, and move it to the left end? (dish as needed)

pbass

The space there is a bit narrower than the width of the chain, so when it came off if just jammed partially in there. Here' a pic.
I don't see any spacers (but I'm a mechanical noob with these things).
This photo is a little wonky---it makes it look like the pulley is noticeably outboard from the smallest cog, but in reality looking at it they appear lined up vertically.

fietsbob

Bent hanger checked and OK? screw in the H stroke limit screw a bit more...

pbass

Yep, hanger looks good. Has not sustained any hits, etc, ever. It's one of these types: https://wheelsmfg.com/derailleur-hanger-322.html
Looks chunky, like it would take a good hit to bend!

I just now tightened the high limit a hair and rode it down the street. Seems fine. If I'm in the smallest cog and attempt to shift higher, it does nothing.

JoeTBM 

Slabach

I have popped my chain off many a time just like what you said, but every time it was due to the shifter being out of alignment or the stop screw needing adjusted.