Concussive weapon quality: knocked prone even if not stunned?

[Concussive weapon quality: knocked prone even if not stunned?]

Yeah, the rules are clear on what happens to the person re: stunned/prone/both, but in the case of the bike, I'm talking about the attack hitting the rider, not the vehicle itself.  What happens to a vehicle whose operator can't take actions?

[Artificer armour special features]

Onboard Medicae is a bit overpowered, yeah.  It's basically Regeneration, and the fact that it functions continuously bypasses one of the main limitations of medicae, i.e. that you generally take damage from several sources before you can be treated, and one check "treats" all damage you currently have.
Overall, most of these lean powerful, but that's the only one that's utterly broken.  I'd say replace it with Regeneration that can function for X number of turns per day.  I love regeneration mechanics, but true regeneration on a PC removes a lot of the narrative tension, as anything that doesn't kill you is rendered utterly trivial the moment combat ends.

[Astartes Boarding Shield]

In response to the original Boarding Shield question, my game went with them being adamantine/ceramite shields with no field generator, (so basically the Storm Shield without the protection field), to allow starting characters to pick up a shield if they really wanted to.

[Concussive weapon quality: knocked prone even if not stunned?]

I assume the damage calculation used is after toughness and armor?
Related question:  What happens in a bike duel, when one rider is hit by a concussive weapon, in each of the following circumstances:
1.  He fails the toughness test, but takes less damage than his strength bonus.
2.  He passes the toughness test, but takes more damage than his strength bonus.
3.  He fails the toughness test and takes more damage than his strength bonus.

Obviously, these results will be stunned, knocked prone, and stunned and knocked prone, but the book is unclear on the exact mechanical effect of each of those in a vehicle (and specifically, in a bike)  Does the bike go Out Of Control?  Is the rider thrown clear?  What happens?