On my 2004 TL, and prior '05 I've many times put a Christmas tree or other relatively light weight item on a blanket, directly on the roof (NOT using rails like may be needed for attaching skiis, bike, kayak, etc). And then heavy duty straps through door frame/below ceiling liner in the cabin keeping everything very secure. Never had any issues.

Does anyone know the capacity of the metal of the roof?

I have an exercise bike similar to a Peloton I'm looking to drive home tomorrow. Box dimensions are of course a couple inches too large to fit in cabin or have hanging out of trunk.
Weight of package a little under 100 pounds.

Anyone have a similar experience or know a resource to check to make sure I avoid giving my TL a big roof innie dent?

Thanks!