On a few laps of Lee Quarry this morning, just about went over the bars coming up out if the 'black' quarry, found what I think is the dreaded chainsuck; as though the chain wouldn't release off the granny ring & carried up to get jammed 'twixt ring & frame. Wouldn't stop hap'nin after that.
Had the bike for 20 months & it's not happened before. Presume either the chain's twisted (doesn't look it) or the ring-teeth have worn / bent to catch / hold the chain on. Probable replacement of g ring to fix.
Does that sound anywhere near plausible? Ta 🙂

read all about it best explanation around.

Probably worn ring, though middles tend to go sooner IME.
Might be time to change the cassette and chain?

This is the perfect time of year for chainsuck. Filth, worn components after the summer and poor shifting due to the unpredictable conditions.
File your granny's teeth to remove any burrs. (She'll thank you for it 🙂 )

Wow, the 1st part of that article sums up my experience this morning pretty much exactly! Thanks Bassspine.

Worn ring.

I too developed it today having dropped my chain landing a jump of the outside of the big ring and putting in half a pedal stroke. At the time didnt spot the one set of inner link plates twisted badly until |I started climbing in granny ring. Just make doubly sure that its not a twisted inner link on the chain. (Carefully straightened with a pair of pliers and a big thumb!)

new rings solved it for me. ( Superstar cause they were cheapest ).

It cheeses me off how expensive chainrings are.

Cheap steel Deore inners and grannies are a good choice, they're cheap and seem to have better wear resistance than, albeit lighter, aluminium rings.