Rear hub loose after several days in the car Hi all – I'm a bike newbie here with what is hopefully a minor problem and would appreciate some help diagnosing what went wrong before I try to fix it myself / bring it to an LBS.

I packed a road bike on a several day car-trip recently. I removed both the front and rear wheel but didn't disassemble any further than this. The car was pretty fully packed, but I made sure to not put any substantial weight on the (aluminum) frame, especially not around the drivetrain and the forks. The wheels were stashed in the back row of the car. (There may have been some pressure on the hubs sitting between the front seats and the back row seats.)

Upon reassembling I find that my rear wheel hub has a few millimeters of wiggle room when the quick release hub is fully tightened. (This seems to convert to about 1cm of wiggle at the rim.)

The bike was basically in tip-top shape before the ride—no issues at all with the bearings beforehand. No major impacts or anything; it just sat in a car for two days.

What might have caused this issue? I can go ahead and tighten the bearings / have someone else tighten the bearings, but I wanted to make sure I wasn't missing anything more serious first. I'm also just curious as well!

If it's relevant, I ride a Specialized Allez Comp with AXIS 2.0 wheels.
I suspect that somehow you've loosened the locknuts while disassembling, and possibly days of vibration have allowed a the nuts to migrate along the thread.  Totally a guess.

The fix is simply to readjust the bearings correctly, and then make sure the locknut is cinched down onto the cone to prevent movement.

If your wheelset has sealed or cartridge bearings then this supposition goes out the window, and something else is wrong.