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Old 05-30-07, 09:04 AM   #1
godogs3
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Hydraulic Disc Brakes vs. Mechanical Disc??

What's the difference between these two types of brakes besides the obvious literal meaning? Is there an advantage for one type of disc brakes as opposed to the other? Is one type more durable or does it last longer? Thanks.
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Old 05-30-07, 09:09 AM   #2
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Oh lordy...here we go again. (at least it's not a Disc vs. Vee thread )

When properly set up, good Hydraulic discs are more powerful and modulate better than good mechanicals. The pad to rotor clearance automatically adjust as they wear. They feel smoother. Their performance is not as adversely affected by the elements. (water/mud on cables = poopy performance)

Hydraulic lines don't break as easily as you may think, so there's no reliability issue on the trail (if you fear being stranded). I've heard that argument, yet I've never heard of a line breakage.

Over all, the only downside to a good set of Hydro's vs. a good set of Mech's is the price.
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Old 05-30-07, 09:13 AM   #3
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Thanks alot
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Old 05-30-07, 09:23 AM   #4
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For what it's worth...I have Juicy 5 hydraulics and I'd never have anything less. Very simple to set up and work on. Very good performance for the money. I love 'em.
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Old 05-30-07, 12:14 PM   #5
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Originally Posted by chelboed
Oh lordy...here we go again. (at least it's not a Disc vs. Vee thread )

When properly set up, good Hydraulic discs are more powerful and modulate better than good mechanicals. The pad to rotor clearance automatically adjust as they wear. They feel smoother. Their performance is not as adversely affected by the elements. (water/mud on cables = poopy performance)

Hydraulic lines don't break as easily as you may think, so there's no reliability issue on the trail (if you fear being stranded). I've heard that argument, yet I've never heard of a line breakage.

Over all, the only downside to a good set of Hydro's vs. a good set of Mech's is the price.
i've had brake pads fall out of my hydro's a couple of times (bent piston), once jamming against the rotor and causing some problems...the big advantage with mechanicals is that you can do most of the fixes on the fly...my wife insisted on mechanical discs when she built her bike so she could carry an extra cable when in the back country (she learned from my experiences)

the dowside for hydros (for me) is that the lbs has to do the work...I don't even have bleed kit
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Old 05-30-07, 12:41 PM   #6
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Actually, this is the argument that I don't quite "get".

jm01's wife wants to carry around a spare brake cable...I think that's smart. But...with hydraulics, you don't need to carry around a cable.

Carrying a cable out in the woods has nothing to do with the caliper and your bent piston issue. It would have been just as easy (or hard) for a pad to fall out of a mechanical as it was your hydro. I don't understand how the pad could fall out, though I don't have much experience with anything besides Avid. On Juicy's, if the caliper is around the rotor...that pad ain't coming out. If the pad is properly installed, it won't just fall out on its own.

You could bend the mechanical clamping mechanism just as easily (or hard) as you bent your hydraulic clamping mechanism (piston).

I'm not saying that in jm01's case he is wrong...I'm just saying that it's hard to bend a piston if you're using the equipment properly and installing it properly (on the Avids that I'm recommending). It's hard for a pad to fall out if it's installed properly. It's probably harder to accidentally rip a hydraulic hose off your frame than it is to break a brake cable.

The Hydro bonus? You don't have to carry brake cables around with you.
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Old 05-30-07, 12:46 PM   #7
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Originally Posted by chelboed
Actually, this is the argument that I don't quite "get".
Me neither. It's not like a bike with one brake is unrideable anyway.
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Old 05-30-07, 12:48 PM   #8
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That's almost a "weight weenie" comment.
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Old 05-30-07, 12:59 PM   #9
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I see this recurring threads sometimes, but I never see anyone advocating for a solution, which would be a wiki, or something of the sort. Has this been proposed?

http://wiki.bikeforums.net/
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Old 05-30-07, 01:02 PM   #10
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I'm anti-wiki.
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Old 05-30-07, 02:25 PM   #11
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At a certain price range I really think that it's better to buy High end mechanical disc brakes than VERY low end Hydraulic disc brakes... just my opinion. And you can easily fix your mechanical disc brakes without any talent of formation
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Old 05-30-07, 03:35 PM   #12
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Quote:
Originally Posted by godogs3
What's the difference between these two types of brakes besides the obvious literal meaning? Is there an advantage for one type of disc brakes as opposed to the other? Is one type more durable or does it last longer? Thanks.
I prefer mechanicals, specifically the Avid BB7.
I have never been disappointed with the braking power or modulation of these brakes. Smoothness and control are simply functions of lever choice and cable selection.
Pair them up with a decent set of levers (such as the Avid FR-5 which is specifically designed for the Ball Bearing Disc or one of the Speed Dial series for extra tuning options) and a set of Dry Cables and you're golden. However running your stock v-brake levers with teflon lined housing and coated cables will offer adequate performance as well.
In terms of ease of maintenance the Avids are second to NONE. The adjustment knobs give you superior "no tool" tunablilty. As a bonus cable brakes are also easier to work on in terms of "in the field" repairs owing to the fact that you can easily get a replacement cable and / or lever at any Mom and Pop bike shop (heck you could go to K-mart and get parts that would work to get you back on the trail that day.)

Contrary to popular myth, I HAVE seen a hose snagged on a trail. Who wants to mess with brake fluid in the boonies?
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Old 05-30-07, 05:28 PM   #13
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For those riding downhill, hydros are preferable as they self adjust. The other benefit of Hydros is that most of them have two pads attached to pistons. Most mechanicals (save IRD Dual Banger) have a fixed pad and a moving pad. As it turns out though, a good set of mechanicals is good enough. With the BB-7s you need only turn the nobs occasionally.

On to braking force ... Mechanicals and Hydros have EXACTLY the same braking force when adjusted properly on the same size wheel with the same size rotor with the same pad compound. You may think that the hydraulic brakes in your car are so powerful because of the "hydro". What makes these so powerful is that the brake system uses engine pressure to amplify your braking. On a bike, it's just your hand. You can increase the mechanical advantage, but this reduces the travel of the pads. In the end, the energy put into those brakes comes from your hands. If you want "more powerful" brakes, get bigger rotors.
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Old 05-30-07, 05:35 PM   #14
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Quote:
Originally Posted by Raiyn
Contrary to popular myth, I HAVE seen a hose snagged on a trail
I agree...I've seen it too...just not a common occurance.
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Old 05-30-07, 06:08 PM   #15
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Originally Posted by DoYlE_RiD3r
At a certain price range I really think that it's better to buy High end mechanical disc brakes than VERY low end Hydraulic disc brakes... just my opinion. And you can easily fix your mechanical disc brakes without any talent of formation
I agree wholeheartedly! I would much rather have a set of BB7's than a lower quality pair or hydros but I have to agree with the majority of the posters in that a quality set of hydros are impossible to beat for power and control.
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Old 05-30-07, 06:09 PM   #16
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Originally Posted by willtsmith_nwi
If you want "more powerful" brakes, get bigger rotors.

I never understood why bigger rotors have more braking power..
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Old 05-30-07, 06:27 PM   #17
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Originally Posted by willtsmith_nwi
For those riding downhill, hydros are preferable as they self adjust. The other benefit of Hydros is that most of them have two pads attached to pistons. Most mechanicals (save IRD Dual Banger) have a fixed pad and a moving pad. As it turns out though, a good set of mechanicals is good enough. With the BB-7s you need only turn the nobs occasionally.

On to braking force ... Mechanicals and Hydros have EXACTLY the same braking force when adjusted properly on the same size wheel with the same size rotor with the same pad compound. You may think that the hydraulic brakes in your car are so powerful because of the "hydro". What makes these so powerful is that the brake system uses engine pressure to amplify your braking. On a bike, it's just your hand. You can increase the mechanical advantage, but this reduces the travel of the pads. In the end, the energy put into those brakes comes from your hands. If you want "more powerful" brakes, get bigger rotors.
More correectly it uses engine vacuum for the assist.

Just sayin'
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Old 05-30-07, 06:29 PM   #18
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Bigger rotors cool quicker.

I also think it has something to do with the further you are from the hub, the easier it is to stop the rotation. Which brings us back to the V-Brake.

I dunno.

It's all techie crap if you ask me. (Although I am enjoying my new disc brakes).
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Old 05-30-07, 06:44 PM   #19
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Quote:
Originally Posted by albyhellscream
I never understood why bigger rotors have more braking power..
Let's start by taking a look at the basic physics involved. There's a law of physics that states how an object in motion has a certain amount of energy due to its momentum. This energy is called kinetic energy. In order for this object in motion to stop or slow down, it must lose some or all of its kinetic energy. A brake does this by converting the kinetic energy to heat.

It's really easy. At your wheel you have a metal disc and a chunk of pad material. The pad squeezes or pushes onto the metal. When this happens, you create friction. Friction generates heat, of course. Since the wheel is turning, then the kinetic energy of your momentum is converted to heat at this point and discharged harmlessly into the atmosphere (with a slight loss of pad material), and your bike slows down. The faster it is going, the more heat is needed to stop it. The more pressure you apply to the pad, the faster it can discharge the kinetic energy. The larger disc aids in the discharge of the heat generated as the increased surface area allows heat to dissipate more quickly, hence better braking.
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Old 05-30-07, 07:19 PM   #20
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Quote:
Originally Posted by Raiyn
Let's start by taking a look at the basic blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, hence better braking.
Actually if the whole reason you get larger rotors was solely for heat dissipation...then why does my bike stop quicker when I'm going 2mph with a 7" roter than when I'm going 2mph with a 6" rotor? There's no heat dissipation involved in such a slow speed yet the 7" rotor is noticeably easier to stop...hmmm.

I'm not mocking anyone here, just having fun.

The reason is b/c the further out you grip on a disc...the more leverage you have in relation to the center point. The reason V-brakes don't really apply to this is because the V-brake mechanism in itself is nowhere nearly as powerful as the disc caliper. If you had a disc caliper mounted all the way out at the rim (like on a Buell motorcycle that I saw) then you'd have rediculous stopping power with the 25" rotor.

I don't disagree that heat dissipation has a good amount of importance especially at high speeds, but the larger rotor does create more leverage for the caliper.
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Old 05-30-07, 07:33 PM   #21
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Originally Posted by Raiyn
The larger disc aids in the discharge of the heat generated as the increased surface area allows heat to dissipate more quickly, hence better braking.
Perhaps more importantly, the greater mass of the larger rotor increases the capacity for heat absorption, resulting in cooler peak operating temps.

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Old 05-30-07, 07:36 PM   #22
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That's the coolest picture, ever!
U take it?
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Old 05-30-07, 07:38 PM   #23
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Quote:
Originally Posted by willtsmith_nwi
On to braking force ... Mechanicals and Hydros have EXACTLY the same braking force when adjusted properly on the same size wheel with the same size rotor with the same pad compound.
I am highly skeptical of this claim. Would you care to elaborate / back this up?
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Old 05-30-07, 07:42 PM   #24
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Originally Posted by chelboed
That's the coolest picture, ever!
U take it?
Me? Ha, no way. I don't know who did.
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Old 05-30-07, 07:42 PM   #25
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I am highly skeptical of this claim. Would you care to elaborate / back this up?
I didn't have the nUtZ to take that one on w/o backup...but I don't buy it either.
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