I think we've all had an experience where we left the QR's just a little loose and cause one issue or another. My latest, like Botto's, was after a good cleaning of the bike where both wheels were off the frame. And additionally, I'd taken the wheels off and put them on another bike for photo op. The second bike's dropouts were much wider so I messed with the nut on the QR as well which I typically leave alone (old bike - no lawer tabs). Well about 2/3 the way through my ride last sunday, and after hammering a 5mi solo run to cap off my 2006mi goal for the year, I start hearing a noise I can't in down. Sounds like something's rubbing, but it sounds metalic like... check the brakes, check the front wheel's bearings, check that it's not my keys in my saddle bag, etc. I stop twice to try to figure this thing out, convinced my cleaning has somehow ruined my Ultegra bearings or something. Finally as I'm riding I glance down to see the tire in contact with the chain stay. And at last the light bulb goes off.