Same problem here. I have tried to fix it, two shops have tried, but it still drops 5 out of 10 times. As soon as Shimano come out with wireless Di2 I'm ditching etap.

My issue isn't that simple.

Update, I'm working on it, Sram is involved, lbs is involved. Situation is improving but I'm not 100% comfortable yet. Remedy so far is to "misalign" the cage. At least according to markings.

And the setup was confirmed to be setup properly when it did throw tthe chain consistently.

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24 Hour World TT Champs-American record holder
Fat Bike Worlds - Race Director
Insta: chris.s.apex

The markings got me close, but it took some trial and error. I had to start from scratch again last night since I switched from an FSA crank to a Red crank, and the spacing/chainline is slightly different on each. It was overshifting a bit, so i turned the upper adjustment screw 1/8 of a turn, and it was still overshifting occasionally. Another 1/8 turn and it's good to go. Shifts like a dream.

What bottom bracket and crank are you running? How many spacers (if any) do you have on each side? Short chainstays and weird spacing could complicate the setup quite a bit.

Trek Madone 56 H2. BB90 and no odd spacers used.

All checked / measured and verified with SRAM. Chainline is dead on as is the measurement of center of spindle to braze on bolt.

At this point I'm about 95% sure it's as simple as NOT lining up the cage to the marks.

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24 Hour World TT Champs-American record holder
Fat Bike Worlds - Race Director
Insta: chris.s.apex

Let me know where the 3 marks end up being when you get it all setup. I'm curious to know what it ends up looking like.

I'd love to be able to move the rear part of the cage outboard a bit. The etap battery is so close to my rear tire (a 40c gravel tire) and moving the rear part of the cage outboard would give me some more space. But, now that it is shifting so smooth as is, i don't really want to mess with it. I may just re-dish by wheel a bit instead so that I can fit a 43.