I know it sounds like a cliche, but I was just riding along, stood up to go up a slight incline and my front hub went pop. Looks like the hub shell cracked and three spokes pulled out. The little ring that usually covers the end of the hub was also cracked. I got the 404s second hand, so I'm not sure how the fix is going to workout; my LBS has the wheel and is going to call Zipp for me. I do have considerable miles in them, probably >10K, but I'm also pretty light and generally easy on bike parts. The bike shop guy said he had actually seen this before. Up to this point I'd been lauding how durable the wheelset was...