BB strength
 

I bought a Trek 920 recently. The shift cables are run interior, rear brake housing runs exterior. The exit opening just above the BB shell is about 5 cm, by about 1/4 in. , full width of the down tube which seems to be 5x5 cm squarish. I've heard BBs are more about lateral strength. Should I be concerned about BB integrity?
Thanks!!

Looks pretty strong to me.

I would have zero concerns. The bottom of the down tube laps the BB shell and the welds at the BB shell edges look really beefy.

thank you for your opinion. I have great respect to you from reading your previous posts.

In theory when compared to a DT that contacted the shell on center (and presumably was fully joined) there will be a lesser stiffness. But in practice these bikes are rather over built and already far stiffer then what we rode when we were young. I think the same can be said for strength too. Andy.

when you were describing the hole, I had a hard time believing it. But it does look fine. Maybe we'll know in 20 years