It's really windy today, and the rain tarpaulin makes a good sail for the bike I'm storing on my balcony. 

Short of actually mooring the bike to something, I decided to just fasten the tarp a bit tauter and tying down _the brake levers_ to stop the bike rolling back and forth. 

With mechanical brakes I would have no concerns about this, but now I'm wondering: are hydraulic brakes also ok with it? After all, they're not static but kind of “self-adjusting”, and the pistons move out over time as the pads wear down.

On the other hand, don't automobiles with hydraulic breaking systems have handbrakes that effectively do the same thing ?

Does this cause any problems if the pressure is kept up for not just _minutes_ as it might in a normal descent, but _days_ on end?