Mechanical disk brake

[[email protected]]

On Feb 14, 9:19 am, "Qui si parla Campagnolo" <[email protected]>
wrote:
> On Feb 13, 10:57 am, "[email protected]" <[email protected]> wrote:
>
>
>
> > I have been thinking about mounting a mechanical disk brake on the
> > front of my fixie.
>
> > >From what I have read, it seems as though mechanical disks are not
>
> > regarded as great brakes and I'm not sure why that would be.
>
> > Also I have read (and I think this was just hydraulic disks) that
> > there is a tendancy for the front wheel to be jerked out of the
> > dropouts under hard braking.
>
> > So my question is, do mechanical disks really have any merit and would
> > a fork with 'lawyers lips' be likely to provide adequate retention for
> > the wheel?
>
> > I'd appreciate it if you would care to give me your opinion on this
> > subject.
>
> > Thanks.
>
> > Lewis.
>
> > *****
>
> After reading some responses and re-reading your question, I gotta ask
> why a disc on a fixie(road, I assume)? As it is, any V or caliper or
> canti can launch ya as it is..discs have certain advantages, mostly
> derived from better braking in the extreme wet/mud and being able to
> ride if ya really wack the wheel. Not sure how this applies to a
> road(assume) fixie..or 'just cuz ya can'?

You got it right here, " 'just cuz ya can' "

I'm 66, retired, a 'car-free' person, and I want a disk on the front.

Also, I have a disk brake front hub that I am going to build into a
rear wheel, with a fixed sprocket. Just cuz I can.

Kind regards.

Lewis.

*****

 

[Skippy]

"Doug Taylor" <[email protected]> wrote in message
news:[email protected]...
> On 13 Feb 2007 09:57:06 -0800, "[email protected]"
> <[email protected]> wrote:
>
>>I have been thinking about mounting a mechanical disk brake on the
>>front of my fixie.
>>
>>>From what I have read, it seems as though mechanical disks are not
>>regarded as great brakes and I'm not sure why that would be.
>>
>>Also I have read (and I think this was just hydraulic disks) that
>>there is a tendancy for the front wheel to be jerked out of the
>>dropouts under hard braking.
>>
>>So my question is, do mechanical disks really have any merit and would
>>a fork with 'lawyers lips' be likely to provide adequate retention for
>>the wheel?
>>
>>I'd appreciate it if you would care to give me your opinion on this
>>subject.
>
> Mechanical disk brakes are still disk brakes, so the wheel ejection
> issue would apply substantially equally to mechanical as to hydraulic
> - IF ANY.
>
> From my personal experience using disks for over 7 or 8 years, I think
> it is an urban legend, but that is merely anecdotal. There have been
> almost as many threads on this subject as helmet threads, and equally
> as divisive, informative, and endless
>
> The only advantage (if it is one) that mechanical has over hydraulic
> is you don't have lines to bleed. In virtually all other respects,
> such as power and modulation, they under perform hydraulics. But
> they are still disk brakes and outperform v-s and cantis by a
> significantly greater factor than they under perform hydraulics.
> Again, IMHO.

I agree apart from bleeding being a disadvantage. You typically only need
to bleed only once at year absolute maximum it's no pain. How often do you
have to tend cables to keep them working smoothly? It's just a job that not
many people are used to doing and DOT fluids are a bit unpleasant. I
remember people finding indexed gears tricky to tune...

I've not met anyone who's had a wheel come off/loosen/move from application
of a disc brake. Anecdotal yes, but also true.

Skippy
E&OE

 

[Qui si parla Campagnolo]

On Feb 14, 10:06 am, "[email protected]" <[email protected]> wrote:
> On Feb 14, 9:19 am, "Qui si parla Campagnolo" <[email protected]>
> wrote:
>
>
>
> > On Feb 13, 10:57 am, "[email protected]" <[email protected]> wrote:
>
> > > I have been thinking about mounting a mechanical disk brake on the
> > > front of my fixie.
>
> > > >From what I have read, it seems as though mechanical disks are not
>
> > > regarded as great brakes and I'm not sure why that would be.
>
> > > Also I have read (and I think this was just hydraulic disks) that
> > > there is a tendancy for the front wheel to be jerked out of the
> > > dropouts under hard braking.
>
> > > So my question is, do mechanical disks really have any merit and would
> > > a fork with 'lawyers lips' be likely to provide adequate retention for
> > > the wheel?
>
> > > I'd appreciate it if you would care to give me your opinion on this
> > > subject.
>
> > > Thanks.
>
> > > Lewis.
>
> > > *****
>
> > After reading some responses and re-reading your question, I gotta ask
> > why a disc on a fixie(road, I assume)? As it is, any V or caliper or
> > canti can launch ya as it is..discs have certain advantages, mostly
> > derived from better braking in the extreme wet/mud and being able to
> > ride if ya really wack the wheel. Not sure how this applies to a
> > road(assume) fixie..or 'just cuz ya can'?
>
> You got it right here, " 'just cuz ya can' "
>
> I'm 66, retired, a 'car-free' person, and I want a disk on the front.
>
> Also, I have a disk brake front hub that I am going to build into a
> rear wheel, with a fixed sprocket. Just cuz I can.
>
> Kind regards.
>
> Lewis.
>
> *****

ahhh, retired, like the sound of that...

 

[G.T.]

Bill Westphal wrote:
> On Feb 13, 7:07 pm, "G.T." <[email protected]> wrote:
>> "Bill Westphal" <[email protected]> wrote in message
>>
>> news:[email protected]...
>>
>>> Bob Flumere <[email protected]> writes:
>>>> Only my opinions below.. subject to all arguments
>>>> to the contrary....... read on....
>>>> I have a bike with Hayes hydraulic disks and others with
>>>> Avid mechanicals.. If there is any difference in "feel", power, or
>>>> ability to modulate, I can not discern it.
>>> I think the hydraulics grip MUCH better.
>> Depends. Have you tried comparing Avid BBs with Juicys? I have and
>> grip-wise there is no difference, in fact, on the rear wheel it takes me
>> even less finger power to lock it up.
>>
>>
> Avid's website lists "intended use" on BB5's/7's, and Juicy 5's/7's as
> XC & all mtn. Juicy Ultimate is XC only, Juicy Code is downhill
> only. Only Juicy Carbon is "intended" for all, i.e. it alone does it
> all. Of course thats coming from the marketing dept, but they might
> have at least glanced at the tech dept memo when they concocted it.
> You certainly do present a spirited defense of the mechanicals, and
> I'm almost ready to toss the Carbons. The dual pad adjustment knobs
> look mighty inviting, as do the "speed dial" levers. Somehow I'll
> survive; maybe I'll send some photos in about 500k miles. It sounds
> like if you solve your fade problems you'd survive with the hydraulics
> too.

I'm going to have my new LBS (I just moved) throw my Juicys back on and
bleed them. We'll see how it goes.

Greg
--
"All my time I spent in heaven
Revelries of dance and wine
Waking to the sound of laughter
Up I'd rise and kiss the sky" - The Mekons

 

[BigBenBiker]

On Tue, 13 Feb 2007 15:19:41 -0600, Werehatrack
<[email protected]> wrote:

> When you find yourself in a situation
>where a rapid reduction in speed is required, does it really matter
>which mechanism is employed, as long as the reduction is achieved?
>Would a rim brake be likely to fail in your type of riding? If so,
>would a disc brake be less likely to fail?

Would the tyre be up to that task, and the wheel would not slide, and
you suddenly find yourself horizontally? Specially, one of the best
advantages of disks is under rain, when the rims are wet (and so is
the tarmac.)

Power without control, in this case either modulation, or the ability
to swing past the obstacle, is useless.

Just my 2 cents - saving for disk brakes, don't ask me more money ;-)

jbr


Ride your 2 wheels, but in order to ride them yet another day!
bbb

 

[Bob Flumere]

On Wed, 14 Feb 2007 11:40:50 -0800, "G.T." <[email protected]>
wrote:

>Bill Westphal wrote:
>> On Feb 13, 7:07 pm, "G.T." <[email protected]> wrote:
>>> "Bill Westphal" <[email protected]> wrote in message
>>>
>>> news:[email protected]...
>>>
>>>> Bob Flumere <[email protected]> writes:
>>>>> Only my opinions below.. subject to all arguments
>>>>> to the contrary....... read on....
>>>>> I have a bike with Hayes hydraulic disks and others with
>>>>> Avid mechanicals.. If there is any difference in "feel", power, or
>>>>> ability to modulate, I can not discern it.
>>>> I think the hydraulics grip MUCH better.
>>> Depends. Have you tried comparing Avid BBs with Juicys? I have and
>>> grip-wise there is no difference, in fact, on the rear wheel it takes me
>>> even less finger power to lock it up.
>>>
>>>
>> Avid's website lists "intended use" on BB5's/7's, and Juicy 5's/7's as
>> XC & all mtn. Juicy Ultimate is XC only, Juicy Code is downhill
>> only. Only Juicy Carbon is "intended" for all, i.e. it alone does it
>> all. Of course thats coming from the marketing dept, but they might
>> have at least glanced at the tech dept memo when they concocted it.
>> You certainly do present a spirited defense of the mechanicals, and
>> I'm almost ready to toss the Carbons. The dual pad adjustment knobs
>> look mighty inviting, as do the "speed dial" levers. Somehow I'll
>> survive; maybe I'll send some photos in about 500k miles. It sounds
>> like if you solve your fade problems you'd survive with the hydraulics
>> too.
>
>I'm going to have my new LBS (I just moved) throw my Juicys back on and
> bleed them. We'll see how it goes.
>
>Greg


The concept that the difference in "feel" and "power" between
hydraulic and mechanical disk brakes is caused by the difference
in the actuation mechanisms doesn't make sense to me.

The leverage and ultimate pinching power at the caliper (on the rotor)
cannot be that much different in the two types, being that the
ultimate pad travel as related to the lever travel can not really be
much different in the two types, mechanical vs hydraulic ...

Now, if you want to compare pad materials, pad area and rotor patterns
and finishes, then I'd go along with the ability to feel a subjective
difference in stopping power (which is never in question, because
any brake can lock up the wheel easily) or "feel" of modulation during
application.

Bike #1; Hayes HX (Hayes pads) Squeals a lot especially in the wet.
Always some drag cuz my rotors are not that true and I don't bother
to loosen and reposition the calipers every time I change wheels.

Bike #2; Avid BB?? (Avid pads) Squawks in the wet, but can be dried
out if you get it hot..

Both can freeze up if you ride through water when air temps are below
freezing. An icy rotor acts just like an iced up wheel!
You get brakes, but not right away.. <BG> Not a problem if
you are aware that it can happen under those circumstances.

I use continuous Avid cables front and rear and they don't seem to get
sticky. I've actually used them on more than one bike when they
were long enough to begin with. I would assume that cable friction
is greater than hydraulic "friction" (non existent) but seems easily
overcome by the two finger pull used on the lever.
Score one there for the hydraulic system ...

I just prefer the simplicity of servicing the mechs and really
couldn't tell you which bike I was riding by the "feel" and "power"
of the brakes..

I've ridden them both on the same day, and any difference that
I might be able to discern is simply masked in the "noise" of the two
different bikes..

I guess the idea would be to use whatever type you prefer, simple or
complex, expensive or not, but
I take issue with one actuation mechanism being superior
to another as far as function is concerned.

To respond directly to the OP.. a mech disk would be ideal for
a single speed commuter.


YMMV <G>

Bob

 

[dabac]

....In the early days of mechanical brakes on motor vehicles, adjustment of the mechanical linkages was always tricky to equalize the braking action side to side and proportion it front to rear

The horror to service such a system!

Early hydraulic systems supplied equal pressure everywhere in the system so the proportioning front to rear could be controlled somewhat by brake construction, size etc. At least there was no side to side problem (in a properly functioning system).
Braking force distribution at the equal hydraulic pressure was simply done by making the rear brakes smaller (or narrower) or both. Not a very good solution BTW.

But rather elegant in its simplicity despite the lack of adaptability. The old VW Beetle with drums in particular succeeded in an amazing feat of unintentional engineering. They used differently sized cylinders front & rear to set up the brake balance. Then as the fad to cut beetles down into beach buggies came into swing it was quickly discovered that swapping the cylinders restored the brake balance to the considerably lighter vehicle.