Thought I might chuck a comment in here, having read robdob’s question about him being a retard. I have a prototype frame that I bought from Brant, a 567, which is a somewhat overbuilt 456, (obviously). All the bits bar forks came from a Hummer. At the time, there were lots of threads on here about Hummers and chainsuck, a problem I suffered from myself.
Using the exact same drivertrain on the Inbred I have the same problem. It’s usually when the chain gets a bit dry or gritty, but not always, the chain sticks to the middle ring when changing to the granny causing the chain to pull up between the ring and stay. To blame Brant is frankly bloody childish, he has designed a frame using existing tubes to get the largest possible tyre between the stays. If the drivetrain causes problems then that’s where the fault lies. You’re obviously not old enough to remember when chainsuck plates were a standard feature on frames because of the continual problem. Many Inbreds have been sold, very few seem to suffer the chainsuck problem. This should give you a clue. FWIW, my drivetrain is six year old SRAM X9 front and rear, with RF Turbine ISIS cranks, an RF ISIS Signature BB, also six years old, and RF middle and granny rings with a bash. Now, it could be that changing to an external bearing BB might well put the cranks out far enough to give the bit of extra clearance to stop it happening. Perhaps Brant could confirm. I can’t afford to ditch an otherwise perfectly good drivetrain, so I’ll see about getting a chainsuck plate, at the moment I’ve just got a couple of jubilee clips around the stay to protect it.