Originally Posted by
Iride01
Some people are horrified if you turn a bike upside down. Don't know why. There were a few early hydraulic brake systems that it maybe played heck with air bubbles getting in the lines, but only one or two early ones.
Otherwise, I think it was some people trying to sell bike stands that started the rumor.<grin>
If it is a (non-thru-axle) drop-out,
Retro Grouch would be right, in my experience. The only way to reproducibly get a conventional quick-release absolutely positioned reproducibly every time is to weight the bike on the wheel. (The same issue can happen if you do it on a stand -- it isn't the upside-won part
per se). With thru-axles, the round hole is symmetric, so it shouldn't matter at all. The only variable (unless you cross-thread it) is the torque.