Originally Posted by
livedarklions
I'm assuming that OP isn't riding a single speed (I could be wrong, but it's unlikely IMO). With a derailleur bike, turning it upside down just increases the chances that you're going to twist the chain (which is a huge PITA). and it's just easier to push the rear derailleur with your hand to create the slack you need to put the chain back on while the bike is on its side. I only have about 45 years experience with derailleur bikes and many, many roadside flat repairs, so feel free to enlighten me as to what I'm supposedly getting wrong.
Another reason NOT to turn the bike upside down is doing so, especially on a paved surface, will scuff your shifters. I've seen it happen. Oh, another reason not to turn the bike upside down - it is unnecessary.