Originally Posted by
bikeinxs
It's an RD8050 long cage ultegra derailleur. It's not supposed to support the 42 but at least on my workstand it seemed to be fine. I'll be testing those wheels out in a couple of weeks so I'll confirm. Note that they just released a new gravel specific drivetrain that will definitely work.
Thank you for your response and I will watch for your response on the 42. I saw that Shimano released a gravel specific drivetrain. The problem is I got the bike last fall, I wish it would have been out last year. Enjoy your new tandem.