Chain dropping off big ring

[ColinJ]

Must be depressing when your derailleur is cleverer than you

It could be worse... You could be a right thicko with an even dumber derailleur!

 

[derrick]

Must be depressing when your derailleur is cleverer than you

Its not a Di2 issue.

 

[derrick]

IT IS NOT A Di2 Issue.

 

[Slioch]

Di2 related question deleted. No need to shout.

 

[Ajax Bay]

Confirm which way the chain drops off the large front ring, please. My suggestion is only relevant if the chain is dropping off to the inside.

I have an idea what it is, just want comfirmation (sic)

Go on; share your idea and then people can shoot at it.

 

[Ajax Bay]

April 2019 thread (which the OP commented on) resuscitated by @BianchiVirgin:

Worn chain and chainring.

anti-cross chaining is the default setting

It will only do that if you proggrame (sic) it.

i (sic) look after a lot of Di2 bikes,

5. When a chainring is worn out, it will produce intermittent chain suck when shifting to the inner chainring, and I suppose it could also cause occasional inward chain drop from the big ring.

 

[ColinJ]

You put a new bottom bracket in and it is too long!

(Is it possible to put BBs of that type the wrong length in? I have certainly had that problem with old-fashioned BBs.)

PS If you call me an idiot for daring to make that suggestion, then I will consider you a bounder and a cad, sir!

 

[Ming the Merciless]

Your chainline is wrong. Get a narrower spindle BB to bring the chain rings in.

 

[HLaB]

I think you can tell Di2 to trim so it adjusts properly. My guess at the moment its just shifting into the big front ring and no more so a shift up the block pulls it back (to the left) slightly which drops the chain onto the small front ring. Trimming might sort that

 

[derrick]

I think you can tell Di2 to trim so it adjusts properly. My guess at the moment its just shifting into the big front ring and no more so a shift up the block pulls it back (to the left) slightly which drops the chain onto the small front ring. Trimming might sort that

You got the smiley right.