I have a weird issue with my Ultegra 11s setup, which until now has been faultless

Shifting into the easiest gear, the mech engages the biggest sprocket, but it makes a ticking noise for 6 or 7 seconds, after which it drops back onto the next sprocket down.

I have set the limit screws, and am sure the mech hanger is fine. The ticking noise makes me think it’s something else, as even with the chain off and wheel removed the mech automatically shifts once the 6 or 7 seconds of ticking are over.

Anyone had experience of this and resolved it?

might need a small tweak in the adjustment. You need to enter the adjustment mode to set in, I think 0.25 mm jumps. A bit like tuning the cable tension when you change wheels as the sprokets may not perfectly align.

Nope, tried that

Something else going on… hence the ticking

Sounds like your limit screw as Di2 over moves the derailleur to ensure it changes & then drops back a little. It sounds like your limit screw is stopping it over reaching & so when it drops back it’s in the next gear. I would try tweaking the limit screw a bit.

and am sure the mech hanger is fine.

But have you put an alignment tool on it? That would be my first job then work from there. If it’s been faultless up until now and you haven’t fiddled with the limit screws then it could well have had a slight knock on the rear mech. I have to check mine every once in a while where it gets knocked in the bike shed at work. A quick tweak with a hanger tool always sorts it.

I don’t have a hanger tool….

if I can’t resolve, I’ll have to find an LBS, just don’t have a go to one here in Somerset since a Ralph Colman shut down

Thanks for the news that it over shifts and then comes back… that explained the ticking and encouraged me to keep trying… a bit of perseverance and we got there

Well done Shek – that certainly sounded like what was happening to me. I do suspect, however, that you have had a very little knock on your derailleur to knock it out OR the rear wheel has not gone back in exactly as it was before……