[dangitboy]

Havent had them yet...probably will on my next new ride. How are they to maintain and repair?


Dave

 

[Yossarian]

I have some Hayes Hydros and love em. In two years I really have not had to do much to them. Changing pads is a breeze, as is resetting the calipers once you figure out what to push and what not to push. this procedure usually immediately follows the first time you squeaze the brake lever with no rotor in between the pads.

 

[sub6]

yeah, most of my disc brakes have been set-and-forget. I've owned Hayes, Shim.XT and Formulas. Much less work than V-brakes, and FAR less than canti-brakes.

Bleeding is pretty easy too but unless you replace a line or something, you shouldn't really ever have to do it. If you have Avid mechanicals, those require that you turn the pad wear dial once in a while since they don't self-adjust like hydros but on the upside, you never have to worry about bleeding them.

Basically, you can't go wrong.

 

[KaTooMer]

One thing not to expect with hydraulic disc brakes is a lighter pull. I had thought that making the switch from V-brakes to discs would be like the difference between cable-operated drum brakes and hydro disc brakes on motorcycles. Not like that, although the pull isn't any harder with my Hayes brakes. Gotta give credit to the V-brakes...very effective stopping power. Just don't get snow on the rims.

 

[dangitboy]

Cool...Yeah I know what ya mean about snow on the rims..lol..Im here in Colorado and dont have sense enough to stay in outta the weather...hehe...

Dave

 

[oldfart]

The first time you have to bleed the brakes is a bit of a challenge particularly if you're trying to use a Hayes manual. The manual is poorly written. The instructions are interupted too frequently with warnings about the fluid and not enough photos for me. But once you done it a few times there is nothing to it. In my experience with 4 years on Hayes Hydros, I needed to bleed at least once per year. I would get lever creep where the dirty fluid would allow the lever to get closer and closer to the bar. The pistons on one cracked I suppose from pushing them back in a bit too vigorously after pad changes. Sometimes the pad retraction would get uneven and if you pushed the pistons all the way in and pumped them all the way out a few times the problem would go away. I've replaced pistons twice. Once through my own stupidity and once because the had cracked with age. I managed to puncture a hose once in a crash where the hose was trapped between a metal sign post and the frame, I think. New pads about every 6 to 8 months, new rotors after 4 or 5 pads wore out.

Compared with cable operated rim brakes, they are cheaper in the long run. In four years, with rim brakes I'd have gone through, 40 or 50 sets of rubber pads, probably 20-30 cables and housings and if I was running regular non ceramic rims probably 8 rims. I probably ride 250 days a year and half of those days are wet.

Plus Hydraulic brakes always work well wet or dry. Performance is better in any condition. They do weigh a bit more. And initial cost is more. I think its just a matter of time before we see discs on road bikes. It will allow really light carbon rims to be used and still have working brakes. Current braking on carbon road rims is kinda crappy, hence Jan Ulrich riding into the rhubarb on that descent in the TdF a couple years ago.

I think you can lighten lever feel with a lighter fluid. I think some early Magura Martas had problems with too thick a fluid. Last time I bought DOT4 at the motorcycle shop the guy told me DOT5.1 was a thinner oil and lever feel was lighter. maybe some one else can confirm that?

 

[KaTooMer]

Originally posted by oldfart
I think you can lighten lever feel with a lighter fluid. I think some early Magura Martas had problems with too thick a fluid. Last time I bought DOT4 at the motorcycle shop the guy told me DOT5.1 was a thinner oil and lever feel was lighter. maybe some one else can confirm that?

Not sure about that...if you can feel a difference, I'd say you've got a great career ahead of you teaching Braille to the blind. This discussion comes up often on motorcycle discussion boards in regard to hydraulic clutches. When they first started showing up on European dirt bikes a few years ago, everyone expected them to have a wonderful feathery-light, one-finger pull. When they didn't, guys tried all sorts of fluids to make the clutch pull lighter, but the fact is, you're using fluid under pressure to complete a task. You're just not going to feel much (if any) difference between oil, water, milk, or beer (although you might feel a slight difference between, say, oil and Mrs. Butterworth's).

I think this concept gets confused with how thicker or thinner weight oils affect suspension damping. With damping, you're forcing a volume of oil through small openings, in and out. A heavier oil is more resistant at moving through those holes, meaning the heavier stuff gives more damping. But brake fluid isn't getting held up by small openings. In fact, it only travels through the brake line far enough to compress the piston in the caliper...an eighth of an inch, maybe?

I'd have to say the guy who told you DOT 5.1 will give you a lighter feel was just trying to sell you the higher-priced stuff. If you have the means, though, it is good stuff. I use 5.1 in my KTM's brakes because I have a tendency to drag the rear brake. Higher boiling point less chance of boiling-induced brake fade.

 

[dangitboy]

Lol...I test rode a Giant with Avid Mechanical Discs today and really liked it, liked the feel...(loved the bike..a Ranier, 14", it was feather light!) Thinking seriously towards a buy here!

Dave

 

[D_D]

From my own experiance and stuff posted here it appears that hydro disk brakes can vary.

I have a hope mini that is very light and I can easerly feel the pads hit the disk through the lever. I have another hope mini that feels no where near as light.

The only problem I have had is that the mini can develop leaks at the top of the caliper and needs to be striped, cleaned and rebuilt to stop the leak. This happens so infequently that it is not really a problem.

All this is minor incoveniance compared to the almost continual maintence of v-brakes.
They work so much better in mud and regain there power much quicker when wet that I don't think I will ever go back to V-brakes except for an urban bike.

 

[MikeD]

Avid mechs are great-for a while. In my experience, and that of another friend (by no means universal, but I've heard it said elsewhere on the net), they work well, but eventually lose adjuster dials to impacts or general jostling, and they lose the ability to hold an adjustment for very long.

They can also be really grabby; it depends how you set them up. That's a strength, though...you can set them how you like once you figure out how it works, unlike most hydros, where you can bleed, change pads, and re-bleed, but that's about it.

Anyhow, hydros 100% for me from now on, but I will give the Avids their due.

MD

 

[skinny]

I would kill for Avid brakes. Not literally, of course (or would I?:devil: ), but they are the best, most fool-proof brakes I've ever used. If you want to have good modulation turn the dials a couple times. If you want insane power, dial em a couple turns the other way. And coupled with the Speed Dials they're beautiful.

Anyways, done with my Avid commerical now

 

[Rustmouse]

Originally posted by KaTooMer
Not sure about that...if you can feel a difference, I'd say you've got a great career ahead of you teaching Braille to the blind. This discussion comes up often on motorcycle discussion boards in regard to hydraulic clutches. When they first started showing up on European dirt bikes a few years ago, everyone expected them to have a wonderful feathery-light, one-finger pull. When they didn't, guys tried all sorts of fluids to make the clutch pull lighter, but the fact is, you're using fluid under pressure to complete a task. You're just not going to feel much (if any) difference between oil, water, milk, or beer (although you might feel a slight difference between, say, oil and Mrs. Butterworth's).

I think this concept gets confused with how thicker or thinner weight oils affect suspension damping. With damping, you're forcing a volume of oil through small openings, in and out. A heavier oil is more resistant at moving through those holes, meaning the heavier stuff gives more damping. But brake fluid isn't getting held up by small openings. In fact, it only travels through the brake line far enough to compress the piston in the caliper...an eighth of an inch, maybe?

I'd have to say the guy who told you DOT 5.1 will give you a lighter feel was just trying to sell you the higher-priced stuff. If you have the means, though, it is good stuff. I use 5.1 in my KTM's brakes because I have a tendency to drag the rear brake. Higher boiling point less chance of boiling-induced brake fade.

That about hit it right on the nose... I wanted to expand on it a bit, though.

Dot 5 is a different material than Dot 3 or 4, and in the end will degrade your seals, they're not compatible fluids

Magura's use another thing altogether.... Mineral oil which isn't compatible with brake fluid (it uses different seals as well)

mineral oil is less hazardous than brake fluid, and is less hydrophilic than brake fluid (doesn't absorb water) but it breaks down most rubber, so requires different seals.

Dot 3 or 4 is hydraulic fluid that doesn't compress quite as much as mineral oil (unless it has water in it) and has a much higher boiling point

Dot 5 has a higher boiling point than dot 3 or 4, but it's more expensive, and uses different seals than Dot 3 or 4.

the DOT 3, 4, and 5 fluids are automotive brake fluids, and get the name from the tests they're required to pass to meet standards (Department Of Transportation's 3, 4, or 5 minute boiling test) Even under extreme circumstances, you're not likely to heat a bicycle's brakes enough for that to matter (hot enough to set fire to brake pads)

the lever feel is unlikely to be affected by the "weight" of fluid in the lines, since hydraulic friction (resistance to flow because of the length of the line, diameter of line, and fluid thickness) is infinitessimal in the systems found on a bicycle. There's just not enough fluid movement to matter.

If you have a great pair of v-brakes, the feel is lighter than the hydros, and the stopping power is almost as good. The difference comes in when there's mud/wet/debris, and severe braking duty. That's when the hydros just blow the other brakes away.

Just like many other things, though, there's a big gap between the engineering and the practical application. What works great for me is a waste of money for others. What works great for others is sure sign of crack use to me.

Go with what feels best for you.

 

[MikeD]

And DOT 5.1 is a different substance altogether than DOT 5.

 

[Rustmouse]

I wonder if DOT 5.1 is compatible with dot 3&4 systems?

 

[MikeD]

It is in Hope systems. They all used to come with 5.1 standard, but you could switch to 4. Now I think they all come with 4 standard, as Hope couldn't really justify the rarer, more expensive 5.1 over the 4; no quantifiable performance gains with it.

MD

 

[Rev.Chuck]

Different fluids in a brake system should make no difference in feel as they are "almost" static. The fluid only moves a very small amount unlike a damper where a large amount of fluid is moving thru a restricted passage. To change the feel of a hydraulic brake requires a change in either the size of the bore of the master cylinder or caliper to change the leverage. 1cm master cylinder bore that moves 1cm and a 10cm caliper that moves 1mm with 10 times the force that is applied at the lever. So you could reduce effort by decreasing the size of the master cylinder but you would have to stroke the lever farther to get the 1mm of movement at the caliper.
Dot 5 fluid is silicone and has a small amount of compressiblity and does feel like it changes the lever pull on something small like a bicycle brake. On a car or motoercycle it just makes it feel kind of spongy, like there is a little air in the system. You would also have to completly clean the system to use it as it is not compatible with traditional brake fluids (dot 3-4)

 

[MikeD]

I don't know if you meant 5.1, and I can't even speak for what 5.1 is composed of, but what I do know is that DOT 5 and DOT 5.1 are DIFFERENT substances and not at all compatible in bicycle disc brakes!!!!!!!!

 

[Rev.Chuck]

DOT 5 is a silocone based fluid not compatible with other brake fluids
DOT 5.1 is a glycol based brake fluid like DOT 3 and 4 so it should be compatible with them BUT, it is Mucho$$ so I wouldn't think any body would want to mix it.
Any glycol based fluid needs to be flushed every now and then because it will absorb water and start corroding alloy parts.

 

[MikeD]

Yeah, that's exactly why Hope is going to DOT 4 entirely...5.1 is hard to find, costly, and troublesome...with no performance gain.

I have a few bottles on hand now because I bought a bunch while I could find it, so looks like I'll be using it for a while to come.

MD