honestly, this episode ended the one way that I most hoped it wouldn't, with Sherlock popping back up and them offering no explanation and just going "lole gotta wait till next season". I mean, I get that he wasn't dead because there were a few articles that mentioned there would be a Season 3, but to have a trick like that pulled off and then hold the explanation for the following season is just aggravating.
as for how it was faked, the bike guy is probably part of it, as it served to disorient Watson and, more importantly, break his view for a second, though I'm not sure how exactly that would play into things. Unless Sherlock is superhuman, the body that fell from the building has to be Moriarty, in which case I wouldn't be surprised if the trick employs aspects of the previous two episodes, namely Sherlock using Molly to falsify the coroner's report/autopsy (as Adler had someone do), and the drugging of Watson (somehow) to make him see the worst-case Scenario of it being Sherlock dead in the street rather than Moriarty. The only two real problems with this are:
1) The witnesses in the street, who when told later that the person who jumped was Sherlock Holmes might be like "yo wtf that didn't look like Sherlock Holmes, it was some other guy!", but they could perhaps just chalk that up to forgetfulness.
2) The bigger problem is that Watson saw the person standing jump, so it's not like Sherlock could just throw the body over the ledge, in which case Sherlock would have to jump. If that's the case, when Watson rounds the corner and sees Sherlock's body,
it's right next to a garbage truck filled with garbage bags, which in many cases in TV translates to "safe landing spot". It's possible that the actual Sherlock landed in there, but then the issue becomes "when did Moriarty fall", to which I would hope to say "the bike guy knocked him down so they could throw Moriarty's body into the street", but the shot of Sherlock lying there happens immediately before Watson gets hit, not after. So really, it's a hole in the reasoning so I can't say it's completely solved, but it's also not apparent how much of the scene was real life and how much was drugged-up Watson-o-vision, so it'll have to wait till the actual deduction anyway.
Also, I am so, SO glad that it wasn't actually a snippet of computer code that moriarty tapped out
in rhythm with his fingers. If that was how it actually was I would go insane.
edit: Alternately, as someone else pointed out to me, it might just be that Sherlock jumped into the truck, then got out and lied down on the street and was dragged off to Molly completely alive, and that having no pulse was the big trick instead. While I don't like that solution as much (as it doesn't utilize previously established things), it's much simpler and doesn't have the glaring holes in it. Though this series hasn't done the "no-pulse inducing drug" thing before, it's not unheard of in uh, certain other Sherlock works so as to not spoil things. :V