low power from brake after bleeding

so i have just bled my magura hs11 with water…everything went well and no air in there.

after putting back on uni and setting up it does work with no leaks it just doesnt seem to have as much power as before.

any ideas?

Try bleeding again:

Did you back off the lever set screw and pad adjustment knob?
Did you pump the lever when you were bleeding?

Did you use water, ahh, just kidding :smiley:

I haven’t run water in my brakes, but on the trials forums it seems like one of the reasons people do it is to get a softer lever feel. Could it be that the reduced power you’re feeling is the softer lever feel of water? I can’t imagine that the trials riders would run brakes with low power, so I think the lever feel, and stopping power must not be the same.

it was because i backed off the screw and forgot to put it back…lol

With a water bleed you should get a harder lever feel. If its soft with water in, there’s air in the system.

Yup, you’re right. I got it backwards.

Using water in your magura is generally speaking not a good thing to do as it causes the seals to expand and deteriate (edd’s failed magura’s in Morzine were an example of this - the damage to the seals had been done before he got them by someone who bleed it with water).

Although it is easier to bleed, it is a short term solution. You should get it bled with the correct dot 4 mineral oil. It not only offers a better uncompressible medium but also lubricates so helping the pistons move… so giving you a smoother action.


Roger is right. Most water bleeding is done by the trials bike community that want a faster brake feel and are willing to deal with the increased maintenance issues the water bleed will cause (corrosion, freeze/thaw issues, difficulty keeping air out of the brakes, damage to the seals from grit/dirt and sweating slaves). If you jump on their forum, you will find out the important tricks like pre-greasing the lever piston and mixing a small ammt of antifreeze into the water to reduce corrosion, but water bleeds are, IMHO, a huge pain, not worth it for the minimal gains a unicycle rider will feel and will likely shorten the life of your brakes. The few times I have been asked to do them for someone, I dread doing them. . .

True story. Someone wanted to send me Magura brakes to “clean-out” and rebleed that they had used human urine to bleed them with on a long ride. . . WTF??? what would you call this “a piss-bleed”??
I turned him down and suggested he try the LBS.


So does this mean you won’t clean my brake lines out for me?

It’s just a got a little wang in it :smiley:

Lets hear it for the fossils in the group that are old enough to quote from or recognize a quote from American Graffiti. . . . Sorry, the answer is still no Ben.


You old farts crack me up!

…except that dot 4 (or any other dot) fluid and mineral oil are not the same thing, and not compatible at all. Magura rim brakes are supposed to use mineral oil (like some Shimano disc brakes, pretty much the same stuff as baby oil or Citroen hydraulic fluid), NOT dot brake fluid.

Sorry for being pedantic :o

lol at the urine story Brycer!


I tried soooo hard not to say anything, haha. Avid brakes take normal DOT fluid though.

I think most bicycle disc brakes do apart from Shimano. Luckily for me the only hydraulic bike brakes in our collection at home are Magura HS33 and HS66 and some Shimano discs, so all take the same stuff :slight_smile:

I have only done motorcycle brakes

It was a surprise to learn some people put water in their uni brakes. On motorcycles, it is common to change the fluid every year because it slowly absorbs water. If your brakes get hot enough to boil water (easy on a fast bike, or a truck on a long downhill), the steam will lock your brakes up. No fun.

I would say read your manual and use the DOT # they advise. Also, never use WD40 near your calipers. The seals are fancy rubber that will swell and go all POS if you wet them with oil products.

Normal DOT 3 or 4 fluid absorbs water (as used in most motor vehicles). Mineral oil as used in Maggy rim brakes doesn’t AFAIK. The water bleeding thing is mostly done by trials bikers, so overheating isn’t a problem (they never ride anywhere!) - I’d always assumed it was just down to laziness (you can just hold the whole assembly under water rather than having to bleed it properly) but apparently some people like the different feel of it compared with mineral oil. Makes the seals go funny though.

But it’s mineral oil in Maguras - not DOT anything.