They used to be more plentiful "back in the day", or you'd rent out a storage space and hope really hard that your gear stayed in it when you weren't around.
Anyway, I'm pretty sure my favorite one that you could just rent a room for a few hours is somehow still open. I say somehow because their rates were always way affordable, but nobody seemed to know they were around. Really nice spaces, and if you wanted to rent their house equipment it was decent, well maintained, and cheap to add on. They also have studio space for photography.
Check out Waveform. Also, pour one out for Music Lab. It may have been a toilet, but it was our toilet.