Sorry I dont live in the area. But if I was a few of you guys living/cycling that area I'd group up for a few nights and try to set up a trap for the bastards. It will mean one person being the 'bait' but have you buddies in close support and beat the living shit out of the fuckers...they'll learn not to mess with cyclists that way.
This is the reason I will move back to Berlin sooner or later. Of course we have crime there as well, but it's far away from this insane brutality of London and it's limited to certain remote areas instead of spreading over the whole city.
What is wrong with these young guys in London, where is this absolutely non-human, horrible brutality coming from?
Circle of violence innit.