On 2018-06-11 08:39, David Scheidt wrote:
Joerg wrote:

:Water in DOT boils out. That's what happens in the open systems on motor
:vehicles. Unfortunately bikes don't have those but if you were truly

What motor vehicle has a brake system open to atmosphere? It ain't
the fifties, man. They're sealed systems. Have been for decades.


What do you think that little hole is for?

https://i.stack.imgur.com/lFHT8.jpg


Brake fluid
in motor vehicle systems is not recirculated much, and the the fluid
that's in the calipers tends to stay in the calipers. It is not at
all unusual to discover a caliper is full of water, while the fluid at
the master cylinder is normal.


That would be a vehicle in a very harsh state of neglect. Probably sat
in a yard for a couple of decades. Water is supposed to mix with the
brake fluid which is why that's DOT and not oil. This lowers the boiling
point but when it does begin to become hot the boil-off can vent out the
top. With a closed system on a bicycle it can't and you have to do that
manually. I have to "burp" my MTB brakes about once a year. Takes a few
minutes, no big deal. The amount of air in there by then is miniscule
but I like the brakes to have a nice hard pressure point.

--
Regards, Joerg

http://www.analogconsultants.com/