Guys, I think I figured it out.
I think I know how Sherlock faked the fall.
When searching for the missing children he found a plant called "Rhododendron ponticum"
Sherlock identifies the vegetation sample from a footprint as belonging to the same plant that can induce a death-like sleep, reducing a heartbeat to almost nothing. It can also result in watery eyes, if Sherlock crying on the rooftop is what Moffat describes as ‘out of character’.
And then I found this.

He's pulling out a packet of blood, just after he fell.

Perhaps the biker that pushed him away was (as we all believe) was used to distract him from Sherlock's body so the seemingly normal crowd members could make a believable death scene. Was this the favor from Molly?
But again, this theory is rather hazy.