hard to pinpoint the root cause... when things break, all we can do for certain is move on.

it's a shame it broke.. i love the look of those hubs, and see them on older specialized MTBs occasionally...
my shoulders, in general, have been thru hell... left(the spiral frac. side) has been dislocated 7 or 8 times., right has dislocated at least 3 times, and has a torn rotator cuff too.
left scapula was broken once... etc.
off road cross country M/C racing is not a gentle sport. I Still miss it... serious fun, and every fiber of your body and mind active at the same time.

the accident that hurt me the most, though.. driving home from work, dozed off.. hit a log truck, head-on.
i scared the crap outta the EMTs when i woke up from death... i recall telling them that the ambulance was the best choice, since morgue wagons pick up dead people ..(i overheard them trying to decide).. i then told them how to get the door open without their hydraulic scissors...but it Really hurt when i tried UNLOCKING THE DOOR myself.... that left collar bone was involved... the 8 shattered ribs, broke left hip, and split sternum didn't help matters... etc.
it was the airbag that killed me. it went off about 5-10 seconds late.....
my hard top '91 Celica bent at both the A and C pillars.. transmission broke off of the engine, etc... but both doors would still open/close!
i bought another Toyota.

funniest thing of that ambulance ride was me coaching the driver on how and when to brake regarding sharp corners... He became a better driver that afternoon!... the third load of morphine kicked in shortly after that driver training session...