About 30g max from my calculations:
Body jolt
That particular incident messed me up but it all depends on head movement. If your head moved it's actually better, that incident was very unlucky for me because I was leaning forward and looking down with nowhere for the head to go.
Also I'm very jolt sensitive these days
Normal concussions happen around 100g - quite a lot really. You basically have to take a hard tackle or have direct head contact on an unforgiving surface at walking speed.
Cushioning will make a big difference, which is why you can let your head fall into your pillow etc.