I pulled my poor bike down yesterday (to help with my poor me). I haven't touched it aside to put it back on the hanger since Spring of 2020. At some point one night it just decided to fall off the wheel hook and slammed into the garage floor. Thankfully, not the car as well, but the riding mower didn't take too kindly. Anywho, picked it up, looked it over and everything seemed ok in a quick look and really didn't think about it again.

I pulled it down, washed it. There is actually a white bike under there. Thought it was greyish brown...I pumped up the tires and took it for a small spin up the street but never changed gears, was on the second cog down. Took it out again today and was riding along at a blistering 7.9 MPH pace...shifted up into the small cog checking operation and just as I am about to 'click' into gear hear the spokes tinging. Look down and the RD was resting within the spoke spacing by a hair width.
Thankfully, I was able to stop really fast and it appeared that a "Brogan Adjustment" took good care of it. Nice not to need a wheel laced and/or RD and a skinned somethingoranother on myself.

#whew

If the bike falls on the right side ALWAYS check the hanger. #learningexperience

If it's a removable derailleur hanger. Take it off and hammer it flat.

I have done that and it worked. I also ordered a new one.

Or just use the proper tool and be sure. You could hammer it sure or you can use the tool designed to properly align it. Plus you could use a HAG or DAG as a hammer : )

If a bike falls in the garage, and there is no one around to hear it, does it make a sound?

ah, but did it actually fall?

good thing when I fall, it's always to the left

Good point. It could have been caught in an alternate reality or some wrinkle in the space-time continuum. Good thinking!

Much like that proverbial tree....

we were around and it was quite a noise, particularly as late as it happened. Skeered the (mess) out of us.