Mechanical disk brake

email hidden said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

Doug Taylor said:

email hidden said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

Quoted message said:

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 switched my rear brake to mechanical because I've either never been
able to bleed it properly or it's sucking in air somewhere. I don't
know about other brands but I don't even notice the difference between
the Avid hydraulic and the mechanical on the rear other than they always
work now rather than fading because of air in the line. With
mechanicals it helps to have a lever on which you can change the
leverage, it really helps with dialing in the touchiness of the Avid
mechanicals.

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

Doug Taylor said:

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.

In my experience, Avid mechanical disc brakes work as well as any
hydraulics of equal rotor diameter I have tried. Hayes mechanical
brakes are not as good, and Tektro mechanical discs are lame. Promax
cable actuated discs are worse than long-reach caliper brakes if
that's possible.

The other major advantage to cable-actuated discs is that their lever
feel and mechanical advantage are tunable by way of the brake levers
that are used. With hydraulics, the levers you ge are the levers
you'll use. The only way to change their feel or response is to
purposely bleed air into the lines.

Chalo

Chalo said:

In my experience, Avid mechanical disc brakes work as well as any
hydraulics of equal rotor diameter I have tried. Hayes mechanical
brakes are not as good, and Tektro mechanical discs are lame. Promax
cable actuated discs are worse than long-reach caliper brakes if
that's possible.

The other major advantage to cable-actuated discs is that their lever
feel and mechanical advantage are tunable by way of the brake levers
that are used. With hydraulics, the levers you ge are the levers
you'll use. The only way to change their feel or response is to
purposely bleed air into the lines.

For the record, I have Avid mechanicals with Paul levers. My Avids
are from about the 2nd year they came out with them, lo many years
ago. It's either me or the brakes, but although they absolutely kick
butt over v-s, I can never get them adjusted with the "feel" that you
get with properly adjusted hydraulics. Like the Shimanos on the
Specialized Epic I rented at Spooner Summit last summer: one finger
tweaking with millimeter increments of modulation, like for when you
didn't quite brake enough before a corner and need a smidgeon of
adjustment once your in :-)

On 13 Feb 2007 09:57:06 -0800, "[email hidden]"

may have said:

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.

There are many models of cable-operated disc brakes, with widly
varying levels of performance. Some are as good as the best V-brakes
or better, and others are as bad as the worst side-pulls. It is
meaningless to state that "mechanical disc brakes aren't as good as
regular brakes", for a variety of reasons. It's like stating that
oranges aren't as good as strawberries.

Quoted message said:

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.

See many other threads here. Some consider the hazard unconscionably
severe, but others find the widespread lack of empirical evidence of
the ejections to be confirmation that there is at best a flaw in the
theory. That theory holds that the problem is endemic and not
properly recognized, and is not alleviated by the currently applied
technology.

Quoted message said:

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?

Adequacy is an issue that you must decide upon for yourself.
Personally, I find the evidence against disc brakes to be less
important to me than the lack of need for them, since rim brakes do
the job for me quite well. 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? These are the questions I
would concern myself with.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

email hidden said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

*****

Lewis...

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.

But:

The Hayes hydraulics are very sensitive to rotor distortion and
will likely drag if the rotors runout more than a few thousandths
of an inch. (There is no positive retraction other than seal drag).

Applying the brake with the wheel (rotor) removed,
will push the pads out and they must be mechanically pushed
back in to put the wheel back in. (Ask me how this happens
any time I put the bike in the back of my SUV with the front
wheel out of it.. <G>

Fluid should be flushed and bled periodically because it seems
to become contaminated over time even though the system
is "sealed".

Overheated fluid can cause "fade".. (more with Shimano hydraulics)
because the mineral oils that they use are apparently more sensitive
to
heat than the "DOT" type brake fluids.

When working with the "DOT" brake fluids, you must use
caution not to get any on the pads, rotor, or any painted
surface. (It will blister paint). Getting any fluid on
the braking surfaces usually renders the pads unusable.

Switching wheels with slightly different rotor positioning
requires resetting the caliper position.. I must do this when
I change to my Nokian spiked tires for ice and then again
when going back the other way.

Brake bosses must be square to rotor and parallel. Some
require surfacing to achive this. Some calipers must be
shimmed to be centered.

The primary reason for the use of hydraulic braking systems on
motor vehicles is to assure equal pressures (and braking action)
on all wheels. Something we don't require, (or want <G>😉
when stopping our bikes.

Now, on to the Avid mechanical disk side:

Simple to adjust, even on a ride. Drag from a slightly warped rotor
is never a problem.

Simple to adjust when swapping wheels. (See above)

Easy to set up initially. The Avid mounting system
doesn't care if the brake bosses on the bike are not
square or parallel. Simple to adjust. (See above <G>😉

Can't "fade".

Can change the brake feel and reach easily with any brand of
"Speed-dial" type levers.

(Can use your old levers if converting).

High quality cables are generally less expensive than
hose, fluid, bleeding, etc.

I could probably go on, but I think you can see the point
from my perspective.
By the way, I DO NOT work for Avid or
sell Avid products.

Perhaps my level of riding does not bring out the performance
differences between the two types, but on every
new build I do now, I simply refuse to spend my time
and effort on the hydraulic disks when I seem to get the
identical results for somewhat less money and MUCH less effort.

I build and maintain my own fleet, so you can probably
spot the bias there. <BG>.

I cannot for the life of me see any positive differences in
performance and refuse to spent the increased time on the
maintenance and set up of the hydraulics for no
perceivable advantage..

BTW, I have converted a couple of friends from "juice"
to mechanical, so we have plenty of spare Hayes hydraulic
parts kicking around. Neither one of them notices the difference
in performance either.. so maybe we just don't get it.. <G>

YMMV.

BTW, I won't comment on the ejection issue.. that has
been thoroughly thrashed here before.. For crying out
loud, you can't get the front wheel out of any fork that I
own without releasing and unscrewing the skewer almost
completely.
How the hell this can happen while riding a properly
closed and locked skewer is beyond my limited understanding.
The skewer would have to practically fall apart
before getting by the damn "Lawyer Lips" on most forks.

Bob

Bob Flumere said:

email hidden said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

*****

Lewis...

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. Kindof like the difference
between manual and power brakes on a car, if you've ever driven a car
w/out power assisted brakes. The difference between my last MTB and
the newer MTB w/ Avid juicy carbon is DRAMATIC, IMO. Or the
difference between a road bike and the hydraulic MTB. Yes, they're
grabby, but you learn to just barely touch them. But if you're not in
serious technical downhill you can probably live without the hydraulic
advantage. I have an "all mountain" setup, not "downhill", but you
want to have total control on the tricky parts, and not to have to
walk the bike.

Quoted message said:

But:

The Hayes hydraulics are very sensitive to rotor distortion and
will likely drag if the rotors runout more than a few thousandths
of an inch. (There is no positive retraction other than seal drag).

Same with the Avid. THey're "self-adjusting", which to me is a
disavantage, because they "self-set" with too little tolerance, and do
occationally (but definitely) rub, but they hardly slow a spinning
wheel on a stand, so probably don't really slow you down. IT's more a
noise issue, like when running down a steep logging road at 30mph. I
would like to know how to get rid of that noise though...

Quoted message said:

Applying the brake with the wheel (rotor) removed,
will push the pads out and they must be mechanically pushed
back in to put the wheel back in. (Ask me how this happens
any time I put the bike in the back of my SUV with the front
wheel out of it.. <G>

The Avid has an insert for shipping. But you're right, prying those
rotors out enough to reinstall the wheel is a problem. But you should
be able to put the bike in the car w/out having the lever bumped. For
me it was ignorantly squeezing it without the wheels, and that only
happened once.

Quoted message said:

Fluid should be flushed and bled periodically because it seems
to become contaminated over time even though the system
is "sealed".

Haven't experienced that with Avid brakes. In about 10 months of
pretty heavy use with a lot of wet, and some mud, they work as if new.

Quoted message said:

Overheated fluid can cause "fade".. (more with Shimano hydraulics)
because the mineral oils that they use are apparently more sensitive
to
heat than the "DOT" type brake fluids.

No fade here.

Quoted message said:

When working with the "DOT" brake fluids, you must use
caution not to get any on the pads, rotor, or any painted
surface. (It will blister paint). Getting any fluid on
the braking surfaces usually renders the pads unusable.

Switching wheels with slightly different rotor positioning
requires resetting the caliper position.. I must do this when
I change to my Nokian spiked tires for ice and then again
when going back the other way.

Same with my Nokians. But only because they have a different hub.
But I just loosen two hex screws holding the brakes on, spin the
wheel, slowly grip the brake lever, and gradually tighten the brakes
to the frame/fork. Takes about 1 minute per wheel. Not a big
problem.

Quoted message said:

Brake bosses must be square to rotor and parallel. Some
require surfacing to achive this. Some calipers must be
shimmed to be centered.

If so, it's a one-time thing.

Quoted message said:

The primary reason for the use of hydraulic braking systems on
motor vehicles is to assure equal pressures (and braking action)
on all wheels. Something we don't require, (or want <G>😉
when stopping our bikes.

Now, on to the Avid mechanical disk side:

Simple to adjust, even on a ride. Drag from a slightly warped rotor
is never a problem.

Simple to adjust when swapping wheels. (See above)

Have that with Avid hydraulics levers too.

Quoted message said:

Easy to set up initially. The Avid mounting system
doesn't care if the brake bosses on the bike are not
square or parallel. Simple to adjust. (See above <G>😉

Have the same with Avid hydraulics

Quoted message said:

Can't "fade".

have the same with Avid hydraulics

Quoted message said:

Can change the brake feel and reach easily with any brand of
"Speed-dial" type levers.

have the same with Avid hydraulics

Quoted message said:

(Can use your old levers if converting).

High quality cables are generally less expensive than
hose, fluid, bleeding, etc.

If you don't have to bleed often, it's not a problem. I'm hoping I
don't need to, but I suspect the LBS is pretty adept at this.

Quoted message said:

I could probably go on, but I think you can see the point
from my perspective.
By the way, I DO NOT work for Avid or
sell Avid products.

Me neither.

Quoted message said:

Perhaps my level of riding does not bring out the performance
differences between the two types, but on every
new build I do now, I simply refuse to spend my time
and effort on the hydraulic disks when I seem to get the
identical results for somewhat less money and MUCH less effort.

I couldn't see going back to mechanical and going down steep
switchbacks. You can push the bike a lot harder when you know you
have the extra brake power in reserve. It's a lot more fun.

Quoted message said:

I build and maintain my own fleet, so you can probably
spot the bias there. <BG>.

I cannot for the life of me see any positive differences in
performance and refuse to spent the increased time on the
maintenance and set up of the hydraulics for no
perceivable advantage..

BTW, I have converted a couple of friends from "juice"
to mechanical, so we have plenty of spare Hayes hydraulic
parts kicking around. Neither one of them notices the difference
in performance either.. so maybe we just don't get it.. <G>

YMMV.

BTW, I won't comment on the ejection issue.. that has
been thoroughly thrashed here before.. For crying out
loud, you can't get the front wheel out of any fork that I
own without releasing and unscrewing the skewer almost
completely.
How the hell this can happen while riding a properly
closed and locked skewer is beyond my limited understanding.

But the problem may exist. So just get a through-axle arrangement,
like Maverick.

Quoted message said:

The skewer would have to practically fall apart
before getting by the damn "Lawyer Lips" on most forks.

But you can get pretty messed up with the front wheel loose and just
hanging by the lawyer lips.

Quoted message said:

Bob

Bill Westphal

"Bill Westphal" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Bob Flumere said:

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.

Quoted message said:

Quoted message said:

Can't "fade".

have the same with Avid hydraulics

Can I send my rear Juicys to you for a rebleed? My fronts are fine but I
have not had success getting those last bubbles out of the rears. Stopping
every 5 minutes on a 6000 ft descent is extremely boring. Haven't had any
such issues since temporarily (turning into permanently) putting on Avid
mechanicals.

Quoted message said:

Quoted message said:

Can change the brake feel and reach easily with any brand of
"Speed-dial" type levers.

have the same with Avid hydraulics

How? You can adjust reach and engagement point with Avid hydraulics, you
cannot change feel like on mechanical "Speed-dial" type levers. As Chalo
mentioned, the only way to do so is by introducing air into the lines which
is obviously dangerous.

Quoted message said:

Quoted message said:

Perhaps my level of riding does not bring out the performance
differences between the two types, but on every
new build I do now, I simply refuse to spend my time
and effort on the hydraulic disks when I seem to get the
identical results for somewhat less money and MUCH less effort.

I couldn't see going back to mechanical and going down steep
switchbacks. You can push the bike a lot harder when you know you
have the extra brake power in reserve. It's a lot more fun.

I'm riding much faster and with much more confidence now that my rear brakes
aren't fading ever since I switched them to mechanicals.

Greg

Bob Flumere said:

On 13 Feb 2007 09:57:06 -0800, "[email hidden]"

Quoted message said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

Quoted message said:

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.

Quoted message said:

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.

Quoted message said:

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?

Quoted message said:

I'd appreciate it if you would care to give me your opinion on this
subject.

Quoted message said:

Thanks.

Quoted message said:

Lewis.

Quoted message said:

*****

Lewis...

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.

But:

The Hayes hydraulics are very sensitive to rotor distortion and
will likely drag if the rotors runout more than a few thousandths
of an inch. (There is no positive retraction other than seal drag).

Applying the brake with the wheel (rotor) removed,
will push the pads out and they must be mechanically pushed
back in to put the wheel back in. (Ask me how this happens
any time I put the bike in the back of my SUV with the front
wheel out of it.. <G>

Fluid should be flushed and bled periodically because it seems
to become contaminated over time even though the system
is "sealed".

Overheated fluid can cause "fade".. (more with Shimano hydraulics)
because the mineral oils that they use are apparently more sensitive
to
heat than the "DOT" type brake fluids.

When working with the "DOT" brake fluids, you must use
caution not to get any on the pads, rotor, or any painted
surface. (It will blister paint). Getting any fluid on
the braking surfaces usually renders the pads unusable.

Switching wheels with slightly different rotor positioning
requires resetting the caliper position.. I must do this when
I change to my Nokian spiked tires for ice and then again
when going back the other way.

Brake bosses must be square to rotor and parallel. Some
require surfacing to achive this. Some calipers must be
shimmed to be centered.

The primary reason for the use of hydraulic braking systems on
motor vehicles is to assure equal pressures (and braking action)
on all wheels. Something we don't require, (or want <G>😉
when stopping our bikes.

Now, on to the Avid mechanical disk side:

Simple to adjust, even on a ride. Drag from a slightly warped rotor
is never a problem.

Simple to adjust when swapping wheels. (See above)

Easy to set up initially. The Avid mounting system
doesn't care if the brake bosses on the bike are not
square or parallel. Simple to adjust. (See above <G>😉

Can't "fade".

Can change the brake feel and reach easily with any brand of
"Speed-dial" type levers.

(Can use your old levers if converting).

High quality cables are generally less expensive than
hose, fluid, bleeding, etc.

I could probably go on, but I think you can see the point
from my perspective.
By the way, I DO NOT work for Avid or
sell Avid products.

Perhaps my level of riding does not bring out the performance
differences between the two types, but on every
new build I do now, I simply refuse to spend my time
and effort on the hydraulic disks when I seem to get the
identical results for somewhat less money and MUCH less effort.

I build and maintain my own fleet, so you can probably
spot the bias there. <BG>.

I cannot for the life of me see any positive differences in
performance and refuse to spent the increased time on the
maintenance and set up of the hydraulics for no
perceivable advantage..

BTW, I have converted a couple of friends from "juice"
to mechanical, so we have plenty of spare Hayes hydraulic
parts kicking around. Neither one of them notices the difference
in performance either.. so maybe we just don't get it.. <G>

YMMV.

BTW, I won't comment on the ejection issue.. that has
been thoroughly thrashed here before.. For crying out
loud, you can't get the front wheel out of any fork that I
own without releasing and unscrewing the skewer almost
completely.
How the hell this can happen while riding a properly
closed and locked skewer is beyond my limited understanding.
The skewer would have to practically fall apart
before getting by the damn "Lawyer Lips" on most forks.

Bob

Thanks, Bob, for your detailed perspective here.

I have certainly seen a lot of comments about Avid and Hayes brakes,
so I guess they must be the most popular ones out there.

The brakes I have are Magura 'Clara' which, now I look closely at
them, are hydraulic. YIKES !!

A friend gave them to me, when I said I wanted mechanical brakes and I
guess he didn't look at them closely either. :-(

Anyway, I plan to go ahead with the conversion and put a mechanical
disk on the front.

Kind regards.

Lewis.

In article
<[email hidden]>
,

Quoted post said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

Everyone knows fixies do not run brakes. I mean, you
immediately lose the coolness factor. Please rethink
this.

--
Michael Press

E-opinions, 24/7.

Doug Taylor said:

email hidden said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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.

good post. add the advantage of hydraulics being self-adjusting and you
have the bases covered. personally, i've never had a problem bleeding
hydraulics, but it seems to be difficult for others.

On 2007-02-14, G.T. <[email hidden]> wrote:
[...]

Quoted message said:

Can I send my rear Juicys to you for a rebleed? My fronts are fine
but I have not had success getting those last bubbles out of the
rears.

I don't know the procedure for bleeding brakes on a bicycle, but I
imagine it involves pumping the lever to try to push the bubbles out to
the bleed screw, holding some pressure, and opening the screw.

That's roughly what you do on a car, but car brake bleeding is much
easier with a device called an "EZ Bleed". That works by pressurizing
the master cylinder to 20psi by replacing its normal cap with one that
has a tube going into the top providing air at 20psi.

The genius of the idea is that you use the car spare tyre, suitably
deflated, to provide the source of 20psi air.

You leave the pressure line connected and then just go round opening and
closing the bleed screws. Works much better than getting an "assistant"
to pump the pedal.

Maybe it would work just as well for bikes?

G.T. said:

"Bill Westphal" <[email hidden]> wrote in message

news:[email hidden]...

Quoted message said:

Bob Flumere <[email hidden]> writes:

Quoted message said:

Quoted message said:

Only my opinions below.. subject to all arguments
to the contrary....... read on....

Quoted message said:

Quoted message said:

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.

Quoted message said:

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.

Bill (not fade away) Westphal

Michael Press said:

In article
<[email hidden]>
,

Quoted post said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

Quoted message said:

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.

Quoted message said:

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.

Quoted message said:

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?

Quoted message said:

I'd appreciate it if you would care to give me your opinion on this
subject.

Everyone knows fixies do not run brakes. I mean, you
immediately lose the coolness factor. Please rethink
this.

--
Michael Press

E-opinions, 24/7.

You have a good point there, Michael, but I am 66 and not THAT much
into being cool. :-)

Kind regards.

Lewis,

*****

Bob Flumere said:

...
The primary reason for the use of hydraulic braking systems on
motor vehicles is to assure equal pressures (and braking action)
on all wheels.

Well, no. A car with a 50/50 brake distribution between front and rear would lock the rears just about every time the brakes are used. There is always a brake bias built in to keep this from happening, and in race cars it might even be adjustable by the driver. But equal pressures left/right for the same axle OTOH is the design target until the ABS kicks in...

Quoted post said:

I have been thinking about mounting a mechanical disk brake on the
front of my fixie.

Quoted message said:

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'?

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On 2007-02-14, G.T. <[email hidden]> wrote:
[...]

Quoted message said:

Can I send my rear Juicys to you for a rebleed? My fronts are fine
but I have not had success getting those last bubbles out of the
rears.

I don't know the procedure for bleeding brakes on a bicycle, but I
imagine it involves pumping the lever to try to push the bubbles out to
the bleed screw, holding some pressure, and opening the screw.

That's roughly what you do on a car, but car brake bleeding is much
easier with a device called an "EZ Bleed". That works by pressurizing
the master cylinder to 20psi by replacing its normal cap with one that
has a tube going into the top providing air at 20psi.

The genius of the idea is that you use the car spare tyre, suitably
deflated, to provide the source of 20psi air.

You leave the pressure line connected and then just go round opening and
closing the bleed screws. Works much better than getting an "assistant"
to pump the pedal.

Maybe it would work just as well for bikes?

Hope sell a kit to do just that for their brakes. Made rather more tedious
than on a car though by the size (or lack thereof) of the reservoir...

cheers,
clive

dabac said:

Bob Flumere said:

...
The primary reason for the use of hydraulic braking systems on
motor vehicles is to assure equal pressures (and braking action)
on *all* wheels.

Well, no. A car with a 50/50 brake distribution between front and rear
would lock the rears just about every time the brakes are used. There
is always a brake bias built in to keep this from happening, and in
race cars it might even be adjustable by the driver. But equal
pressures left/right for the same axle OTOH is the design target until
the ABS kicks in...

Yes dabac ..

I do stand corrected. I did not state my point quite accurately..

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

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. <G>

Nowadays we have all different kinds of proportioning systems, some
of which sense the load on the rear axle and proportion the hydraulic
pressure to attempt to avoid premature locking of the rear brakes and
of course, modern ABS systems which will prevent the locking of any
wheel in a panic situation by means of rotation
sensors at each wheel and electronically controlled hydraulic
modulation of each individual brake to prevent complete lockup and
allow steering in a panic stop.

Hope I cleared that up some.. I never meant to say that the
braking effort on "all" wheels should be the same.. only that
the hydraulic pressure in the early systems was equal at all
four wheels eliminating the complex mechanical linkage
adjustments.

Bob..

"Bob Flumere" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Nowadays we have all different kinds of proportioning systems, some
of which sense the load on the rear axle and proportion the hydraulic
pressure to attempt to avoid premature locking of the rear brakes

The way hydropneumatically suspended Citroens did it is quite clever - the
rear brakes are fed off the rear suspension.

cheers,
clive