sp00ki

the 15" lever isn't going anywhere. it's pressing (in 306 degrees) against the walls of a pressed headset (at the top) which is pressing (in 360 degrees) against the headtube-- all with 0 play. at the bottom, it's pressing (in 360 degrees) against the part in question which is again pressing (360 degrees) against the headtube-- also with 0 play. unless you're saying that any sort of jumping on a bicycle ovalizes an aluminum headset + headtube over time, there's no physical way that the steertube is all of a sudden able to rip through an upper headset cup + headtube + this thing (either 1/8" of aluminum or titanium). you say you've installed one, but it appears you weren't paying close attention to what was actually happening... any pressure applied to the lower headset cup means essentially that your steertube bent enough to bypass the top headset+headtube and the heads-up + headtube. in other words, your fork's steerer snapped -- and not at the crown, the fork's weakest point. if you were to put the above scenereo into a physics simulator, i'd bet $5 grand that the steertube and crown separates before the steertube snaps 1000 times out of 1000. if you're telling people not to ride tricks in the street, this should be why-- not because you think the steertube is going to magically snap or bend at one of its strongest points (as far as leverage is concerned... this might be plausible if you were talking about the middle of a steertube, but we already went over how that's not possible either).

also: the oversized lower headset cup doesn't come into play with what you're saying. the lever acting on the bearings or anything apart from the walls of the headset inside the head tube has zero to do with what we're talking about. the thickness of this material hasn't changed for decades (ever?), and is exactly the same on road cycles as it is on mountain and bmx bicycles.

honestly, just because something looks different or unfamiliar doesn't mean you should be scared of it. until you test something (or at least spend a few minutes actually thinking about how it works), you shouldn't voice so matter of factly an opinion on it.

i'd be willing to bet that as recently as five years ago, you were one of the guys saying "carbon breaks too easily, it's not safe."

one more thing:
i'm pretty sure they don't make bicycles for 350lb gorillas... or are we talking about unicycles here?