http://www.twitch.tv/mamamia1001/c/4392096

I think this might be a little faster than the current strats, but I haven't timed it properly.

Getting the bike there is really easy, you drive along the wall and just jump off, no need to break.

ETA: For anyone who doesn't wanna watch this on a potato - https://dl.dropboxusercontent.com/u/60029413/gta-vc%202014-06-03%2023-17-19-362.avi