If I store my bike for a period of time is it ok to hang upside down from the rafters ? Does it put any stress on the wheels?

When you ride- your weight is actually hanging from the upper spokes of the wheel. You're putting much much lower loads on it when it's hanging upside down. I hang most of my bikes above my car in the garage. Just really make sure you get the hook into a rafter or you could have a big dent later in your car.

Remember you can alternate the bikes- front/rear and then rear/front on the hooks so you can get them much closer together. I have 10 bicycles above my car with lots of room for other stuff- including the garage door that has to open...

jeff

Why not just lie it down somewhere in your living room..?

Some people consider them art and hang them from the wall of the living room during the winter.

Yep... or when you're pissed off waiting for replacement tyres to arrive because you blew the rear tyre on a high speed descent, the ones you want are backordered everywhere and everyone's all busy hanging out at Interbike. This is from almost exactly two years ago...

damn, khuon, swanky getup.
if you run hydraulic discs or some suspension forks, hanging upside down is not a good thing. air from the 'open' reservoirs in the handles will slowly bleed into your slave chambers, resulting in pad rub and spongy feeling brakes. with the forks, the oil can creep past seals.

in the winter? I hang both my bikes in my Living room whenever I'm not riding them. And at work I have a hook in my office to keep my commuter. They are much too pretty to leave outside.

Damn I wish I had a bike like that to hang next to my computer :/