Hanging uni upside down with brakes

I’m tempted to move my brake from my 24" muni - which I use more for XC at the moment, no steep hills around where I live - to my 29" road uni. It’s got short cranks and I want to know if I like brakes on that.

I store that one in the apartment, there’s a high shelve that’s perfect because the uni hangs from its pedal… upside down. My understanding of physics (and my experience in bleeding car brakes) is that it could cause a potential issue with air traveling from the lever to the caliper if it had the disc brake. Or are the bike brakes a closed system, in which case it shouldn’t be a problem?

Can’t quite find a definite answer from mountain b**e users, so I thought I’d ask my fellow unicyclists.

i have used various hydraulic brakes on many mountain bikes and never had any problems with them being stored upside down which i did/do a lot as i run fox forks which need storing upside down.

with hydraulic brakes if you get a problem with bleeding them you can put lever at highest point,pull lever in and place cable tie around it holding lever in and leave over night.next morning remove tie and brake will be nice and solid.

Magura makes a big point about how theirs are a closed system. I’m not sure about others. If it doesn’t have a visible reservoir, you’re probably good.

Never had any issues with the Shimano SLX I unse on my muni. But, on my be (whichs only purpose now is to collect dust) I have the Avid Elixier R SLC. Once I cleaned up my cellar, pushed the be on its rear wheel an the front wheel in the air throug my cellar and then pulled the front brake lever. At this moment, the caliper was higher than the lever … and gues what … no preassure at the second pull. I had to bleed it again. I’ve heared several times, thet the Avid brakes are prone to that.
On my muni with the Shimano brake, I can pull the lever in any position without any problems.
So I guess, it depends on the brake.

Since avid brakes use a closed system with no reservoir this behavior means that you must not have purged all of the air when you bled it. Admittedly,avid brakes are difficult to bleed well, and this probably leads to problems like this being common.

Shimano on the other hand is an open system that allows air in the line to percolate into a reservoir that replaces it with fluid as you ride. I have had to bleed Shimano brakes that were stored for long periods upside down because the air can eventually get past the bladder back into the line and to the caliper. Shimano systems are really easy to bleed, and a pressurized bleed from the caliper to the lever gets the air out really well. I have had to re-bleed brakes that customers brought to me after having tried the “gravity” bleed without success. If someone did this with moderate success that could be a reason that upside down storage has been a problem on Shimano brakes, but that’s just a guess.

My one uni with hydraulic brakes; my 36", has been stored upside-down until we moved to the new house (June). Here, it’s still waiting for me to get the hanging situation figured out. All I have up so far are four bikes (not mine), which took up the most floor space. Most of the unis are waiting in a sad pile…

Thanks for the feedbacks!
It makes sense that manufacturers came up with a sealed system - even if if has to include a bladder for extra fluid. A bike is being tossed around, dropped, carried, and it’s also going down some trails that put it under a lot of vibrations. A car/motorbike system with a reservoir at the top (but air) would be very likely to fail, or at least to get some air into the system at some stage.

Now I just have to get on the case and move the brake from one uni to the other!