[Closed] hydraulic brakes

Noooo. Do not tell me you are serious.

Knew a guy who ran his on bath water (used or new, I never ask..)

He said they worked fine, just got really hot easily.

Some of the trials riders do this. They bleed the brakeset whilst it is submerged in a bath of water to ensure there is absolutely no air in the system. It works for them because generally they are using their brakes at low speed and so heat build up isn't a problem.

Is this april the 1st?

I find soft cheese to be the best substitute........

By the look of it some off you think its legit while others think I'm bumfin my gums.I was curious as to see if he was pulling my chain and looks like it might be do-able.not that I'm thinking off doing it.

Well a I right in thinking that you can't compress a liquid? If so, there's no reason it shouldn't work.

Edit: I'm not an engineer!

Do you keep your bikes in an unheated shed? Do you ride in the winter?

Guessing by the typing your in Scotland or at least Scottish. So it gets quite cold in the winter. With the freezing point of water being around 0°C and the freezing point of DOT 5.1 being around -55°C I know what I would rather use in the winter.

Guessing by the typing your in Scotland or at least Scottish. So it gets quite cold in the winter. With the freezing point of water being around 0°C and the freezing point of DOT 5.1 being around -55°C I know what I would rather use in the winter.

Also at the other end of the scale water boils at 100 degrees, my brakes get hotter than that and I'm a right mincer.

When you say 'trials riders do it' you presumably mean using magura rim brakes? If so those use mineral oil not DOT don't they?

retro83 - yes HS33's. Don't think that water would last long in a disc set up 🙂

Hey Hainman why don't you give it a try and let us know how you get on?

aye mate scottish .on serious note i'll stick to the mineral oil thats in my brakes already as it gets ****in baltic about here never mind the winter.i just wanted peoples opinion on this thats why i asked.maybe he runs radiator pipes next to his brake lines haha or he stores the bike indoors.i found it interesting and obviously got you guys attention aswell!!

No worries dude - it was an interesting point and made me consider all the plus points of hydraulic fluid and how the brakes work etc.

I heard on holiday in the Alps one guy used olive oil for a couple of days.
Never heard of using water though

I reckon it'd work OK - water is a perfectly valid choice for a hydraulic fluid - it's certainly been used in the past, and in places where leaking oil is unacceptable people still use it. Problem is that hydraulic fluids serve other functions beside simple power transmission, so:
-It may dissolve more air than oils, which could come out of solution and cause problems when it gets warm
-It has a low viscosity, so leakage might be an issue (but seals on brakes are pretty good, so probably fine)
-It won't lubricate as well as oil - you might notice the extra friction/stiction. However, having played around with dry hydraulic brakes, they're pretty smooth, so I doubt this would be an issue
-It has a lower boiling point than oil - this is the main issue (but not for trials riders....). Over time, car brake fluid absorbs water, dropping the boiling point to a level that eventually gets dangerous. New DOT4 boils at 230C.

I do wonder though whether you'd mostly get away with it - the thermal conductivity is probably rather higher as is the heat capacity, so the performance is possibly closer to oil than you might expect.... The dissolved air might be the real issue though.

Note also, that cooking oils have few of these limitations - they're in fact designed for high temperature operation!

Personally though, I might stick with DOT 4 and mineral oil 😉

Why bother, Dot 5 is not exactly the most expensive liquid on earth.

Next time I'm in the chippie I'm gona get fish supper and a top up for ma brakes haha.seriously though seems like loads of different methods for whatever suits your means and needs.I suppose to a degree oil of sorts would work as the heat temp is high.although might start smoking haha

I guess it would be useful in emergency situations.

Arrived in the Sierra Nevadas last year to discover that the bleed plug on my front brake had fallen out on the plane. (Thanks Hayes - brilliant design). Anyway we were in the middle of nowhere without even a shop, let alone a garage so I siphoned off some brake fluid from the rental car to top up the brakes.

With hindsight we could have used the olive oil that was plentiful in the region.

Dirtynap - Member

Why bother, Dot 5 is not exactly the most expensive liquid on earth.

[pedant mode /on] Actually you mean DOT 5.1, DOT 5 is a very different fluid [pedant mode /off]

You resurrected a thread just to say that?

[pedant] [/pedant]

no need for words "on" and "off" in tags!!