Δαφνη Ευτυχια Αρθουρος

I need a collective noun for illegal dirt bikes.

realinterrobang suggested "a herd of iron horses", to which I commented that these are more like iron ponies than iron horses ... but at the moment I'm leaning toward a "pod" of illegal dirt bikes (though I can't put my finger on why).

(Hmm. They're loud, so maybe a "loud" word. A "crash" of illegal dirt bikes?)

Suggestions?