Originally Posted by
themp
If you hang your bicycle vertical and it has hydraulic brakes, make sure you hang it with the handlebars in the up position, higher than the calipers. Had one bicycle with Hope hydraulic brakes and if you stored the bicycle with the front wheel down, air from the master cylinder would travel to the caliper and the brakes would be spongy. After switching to the handlebars up, no problems from then on. Other manufacturers of hydraulic brakes do have have this problem, but at this point I just do handlebars up on bicycles that have hydraulic brakes.
I have a Cannondale SuperX with Sram Rival HDR and regularly hang it from the rear wheel and from both wheels upside down. I've been storing it that way for 3 years and have yet needed to bleed he brakes.