Is it cos they’re not bled properly and there’s air in the system? Should well sorted brakes be okay upside-down?

if they have air bubbles in them or not enough fluid (same thing really) the bubbles migrate to one end or the other (i think!)

Most brands have no problems being stored upside down assuming that they’re properly bled. As above, it’s air in the system that normally sits in the reservoir (so doesn’t necessarily cause direct problems) that then moves into the main system when stored upside down that causes the problem.

It is because they are not closely related to bats, which, as we know, prefer to be stored upside down.

That, or voodoo.

strap the lever back to the bar and leave over night. this will allow the bubble back into the reservoir and they will be good as new if not slightly better. for a permanent fix, take the res cap off and fill to brim and don’t let a bubble back in refitting the diaphragm so system is totally air free.

yeah if they’re avid juicys you can bleed the lever after storing upright to suck the air out. Dunno if I was doing it wrong once but it took 4/5 bleeds to stop pulling loads of air out. And they hadn’t even felt so bad previously.

I’ve got the bike stored upside down and wheel-less next to me in the office as we speak, as I’m planning an after-work ride.

Fingers crossed there’s no air in the system then!