The "gang" is very careful about what they say, to avoid statements that can hurt them, and to also allow the opportunity to claim something that might help them. A quick review of their history shows that one of the things they do is organize group rides as a "show of force". It pleases them to have video of a large group that suddenly shows up at an unexpected location, and the overwhelmed police clearly avoid starting any "incident", which boosts the ego of the group and reinforces that...when they are massed, the police are "afraid" of them, giving them a small window of opportunity to quickly perform any one of several actions:
1) Instigate one or more "bump and pay" incidents, with dozens of gang members willing to act as witnesses. Insurance companies will often settle out of court. Notice the starting incident was NOT in front of a part of the city where there are lots of pedestrians as potential counter-witnesses.
2) This gang is known to video-record radical stunts that they perform on city streets, and then sell DVD copies as a source of income. One action that is necessary is to block off a street to avoid accidental car crashes with the stunting motorcycles. The "bump-and-pay" incident may have served a double-purpose of blocking this major highway (which happens to have very few side-streets), in order to video stunts.
Why would you risk having your expensive motorcycle wrecked performing stunts? Is is just for the fame, or the few bucks you might get from DVD sales?
On occasion, chunks of these groups are cordoned-off, and their motorcycles confiscated. Many prove to be stolen, and many do not have a license plate. Some were found to have an electric "plate-flipper". When riding in public, the plate is visible, but...when to think you want to do something illegal, you press a button and the plate flips-up to an unreadable angle.
Helmets, masks, goggles, gloves, no license plates, and riding on stolen motorcycles...if any stunt results in a crash (or a police-chase), the rider just walks away, and jumps onto the back of a friends motorcycle for a quick getaway...
When questioned, each rider said they were riding alone, and were not part of a "group"(yeah, right...).
edit: some riders may have indeed been riding along, and not part of this group, but this size of a motorcycle massing was not an accident of timing...it was planned.