Ditto here. I find the locking tabs on bikes to be too much of a pain to use. Plus I'm ussually walking away from the bike by the time the helmet comes off anyway....(Take the left glove off, put key in pocket, take 2-3 steps while the right glove is removed, another 4 to pop ouf of the helmet, place both gloves in the helmet, another step, start pulling off the jacket. Yeah, I'm a creature of habit)
As for gyms, the most annoying part is that the helmet wont fit in a standard size locker. So the only choice you got is to ask someone to keep it behind their desk.. Few people ever mess with it.