Ive got a hoarder stash hanging in my attic. It gets pretty hot up there in the summer and I run a couple big fans to keep the heat down, but the bikes do a heating cooling cycle everyday. I try and clean every bike and then soak it down with wd-40. Some of the bikes have been up there 4 years. I think that there might be a little more rust on a things that were already rusty, but the clean bikes are the same. I havent frame savered anything but most of the bikes have the seat post pulled as seats really dont survive the heat. All my "keepers" are in an insulated garage with a dehumidifier though.