I installed the XTR display on the bike this weekend.

I looked at the situation with the front derailleur cage. It does appear that the guide is rubbing on the chain with small front x any of the three smallest rear cogs. I tried to adjust this out without success.

I took it to my LBS (not the builder of the bike). They are not really familiar with Di2 on a tandem. They noticed that the rear hub is set up for a disc (but no disc installed). They wondered if this might be the cause of the problem. They thought that a disc hub might shift the cassette further outboard.

Is this true? I spec'd the bike to be "disc ready" but went with rim brakes. If having a disc hub in the rear compromises the chainline & makes cross-chaining worse, I want to get rid of the disc hub.

I would take the bike back to the builder but they are on the other side of the country so this is not practical.

Experts please?