I am trying to figure out the right part to replace this bolt that broke. It went through the rear frame of bike into derailleur to a shimano dyna sys II unit. I believe it is a hanger bolt but the ones I find online don't look exactly like it as it has a smooth portion (where the break is) that I don't see on the online. Please see attached photoS and help. So lost.
This looks like the Syntace 142 mm X-12 axis bolt that also serves as the derailleur hanger.
Syntace catalogue (there are several lengths):
In shops (be sure to buy the right length):