Short Report: Magura HS11 hydraulic rim brakes
Andre Jute
rim brakes on my Utopia Kranich in the wet.
The Magura HS11 is fitted to the Utopia bikes without the booster,
Utopia claims for increased controllability. They're probably right. I
tried the HS11 against Shimano 70/75 series roller brakes and 475
series cable operated disc brakes. The discs are pretty much on/off.
The roller brakes are more controllable but you still want to pay
careful attention to what you do, or they will plant you on your face.
The HS11, sans booster, can just barely be squeezed hard enough in
perfect conditions to lift the rear wheel a couple of millimetres. One
would need really very strong hands to be in danger of going over the
handlebars with the HS11.
As the price for their controllability and progressivity, the HS11
offer the least stopping power of the three I rested. (It is too long
since I owned traditional rim brakes to remember what they were like.)
That applies even in the dry. In the wet, Shimano's roller brakes
leave the HS11 for dead.
How relevant this differential is depends on how one expects to ride.
I ride hard and brake hard. The HS11 is good enough, just. In the same
use, the Shimano 70/75 roller brakes, and the disc brake even more,
require constant awareness if one isn't to lock them up with painful
consequences. The HS11 are really a lot more controllable. In an
emergency the HS11 in the wet might prove to be not good enough, but
the roller brake and the disc might make the danger worse by locking
up and sending the rider out of control. Swings and roundabouts.
I'm was a writer before I was a sportsman (I published my first book
at 13) and now I'm a writer again; my mind is always on detached duty,
elsewhere. On the other hand, in my middle age my reflexes are still
trustworthy. Those Magura HS11 and I will get along very well indeed
precisely because they aren't strong enough to cause a disaster in a
moment of inattention, yet good enough to stop my 210 pounds reliably.
They don't seem to lose enough advantage in the wet to undermine this
low-attention benefit.
Whether the HS11 are good enough for a sporting rider who wants the
best brakes, and is prepared to pay the price in constant attention,
is a different matter. There is a brake booster available for the HS11
which is said to give greater stopping power at the price of less
docility; the HS33 has a smaller cylinder and is more powerful still
at the price of yet more controllability. Quite a few manufacturers
and cyclists in Europe who can easily afford to fit discs instead fit
the HS33 as a sporting/controllable/low maintenance alternative to
discs.
I was planning, before I tried them, to chuck the HS11 in favour of a
disc at the front at least, but have now changed my mind. I'll keep
the HS11 for the time being, at least until I discover how they behave
in an emergency; it's the first time I've ever had brakes that
understand that an artist isn't necessarily always there.
Andre Jute
We must start from where we have arrived -- Friedrich Nietzsche
probably didn't say it
jim beam
> Yesterday I had a chance to try out the standard Magura HS11 hydraulic
> rim brakes on my Utopia Kranich in the wet.
>
> The Magura HS11 is fitted to the Utopia bikes without the booster,
> Utopia claims for increased controllability. They're probably right. I
> tried the HS11 against Shimano 70/75 series roller brakes and 475
> series cable operated disc brakes. The discs are pretty much on/off.
> The roller brakes are more controllable but you still want to pay
> careful attention to what you do, or they will plant you on your face.
> The HS11, sans booster, can just barely be squeezed hard enough in
> perfect conditions to lift the rear wheel a couple of millimetres. One
> would need really very strong hands to be in danger of going over the
> handlebars with the HS11.
>
> As the price for their controllability and progressivity, the HS11
> offer the least stopping power of the three I rested. (It is too long
> since I owned traditional rim brakes to remember what they were like.)
> That applies even in the dry. In the wet, Shimano's roller brakes
> leave the HS11 for dead.
i looked at that frame and those brakes and considered posting then, but
now you force my hand. stand and watch the frame closely while you
operate those brakes. with those skinny stays, i'll bet you a used
donut you see considerable frame flex - essentially, you can't generate
the pressure to make them work well. not a problem with cheapo heavy
frames and aluminum frames of course, but lightweight steel, the flex
means it'll give you drag but not much else.
what you need is one of those horseshoe things that mounts between the
posts which reinforces the stays. i have a honking great cfrp one from
salsa which turned the rear of my koga-miyata into something distinctly
un-scary.
and unfortunately, unless you have caliper brakes which press against
themselves, you're going to have the same kind of problem with any kind
of rear frame-levered brake on this bike, not just the hydraulics.
Clive George
news:4NSdnUKCCZwAPevU...@speakeasy.net...
> Andre Jute wrote:
>
>> The Magura HS11 is fitted to the Utopia bikes without the booster,
>> Utopia claims for increased controllability. They're probably right.
> what you need is one of those horseshoe things that mounts between the
> posts which reinforces the stays. i have a honking great cfrp one from
> salsa which turned the rear of my koga-miyata into something distinctly
> un-scary.
Maguras really need boosters - the common name for the "horseshoe thing"
you're talking about.. It makes a huge difference to how good they are.
Without, they'll definitely be softer, which could be interpreted as
"Controllability", but actually means "not as good". With one, it's just a
different feel - pressure rather than movement.
The booster for maguras is different to the ones you're thinking of - it
mounts to the top bolts, and that does fine. You can get ones which mount to
all four (the lower one being the post bolts you're referring to), but that
isn't really necessary.
And yes, they do flex alarmingly when installed on steel frames without a
booster :-)
Andre Jute
> Andre Jute wrote:
> > Yesterday I had a chance to try out the standard Magura HS11 hydraulic
> > rim brakes on my Utopia Kranich in the wet.
>
> > The Magura HS11 is fitted to the Utopia bikes without the booster,
> > Utopia claims for increased controllability. They're probably right. I
> > tried the HS11 against Shimano 70/75 series roller brakes and 475
> > series cable operated disc brakes. The discs are pretty much on/off.
> > The roller brakes are more controllable but you still want to pay
> > careful attention to what you do, or they will plant you on your face.
> > The HS11, sans booster, can just barely be squeezed hard enough in
> > perfect conditions to lift the rear wheel a couple of millimetres. One
> > would need really very strong hands to be in danger of going over the
> > handlebars with the HS11.
>
> > As the price for their controllability and progressivity, the HS11
> > offer the least stopping power of the three I rested. (It is too long
> > since I owned traditional rim brakes to remember what they were like.)
> > That applies even in the dry. In the wet, Shimano's roller brakes
> > leave the HS11 for dead.
>
> <snip>
The text you snipped answered most of your points, at least by
implication. First I'll restore the text, then I'll connect it to your
points.
****
****
> i looked at that frame and those brakes and considered posting then, but
> now you force my hand.
What are you, some kind of an internet efficiency vigilante? Do you
really think a fellow who designed cars and racing yachts doesn't know
about stiffness? You should get a copy of my book, Designing and
Building Specail Cars, from the library. About a third of it is given
over to various approaches to stiffness.
> stand and watch the frame closely while you
> operate those brakes. with those skinny stays, i'll bet you a used
> donut you see considerable frame flex - essentially, you can't generate
> the pressure to make them work well. not a problem with cheapo heavy
> frames and aluminum frames of course, but lightweight steel, the flex
> means it'll give you drag but not much else.
For a metallurgist you're disturbingly full-on, full-off, Jimbo. Ever
hear of rivetted ali aeroplane wings that are supposed to flex? Or the
swing arms on common early VW and Porsche that supplied the necessary
compliance by flexing?
> what you need is one of those horseshoe things that mounts between the
> posts which reinforces the stays.
The manufacturer says they left them off to increase controllability.
Yeah, sure, I know the cheap shot from those who want to prove how
clever they are is that "controllability" is the same thing as "not
maximally efficient". I suspect that the people who buy these bikes
are middle-aged and often buy them as a first bike. They're not
interested in extracting maximum efficiency from every component, nor
are they interested in sitting there hunched over in fear at what
their own brakes will do to them if they squeeze them marginally too
hard. Maximal efficiency is an obsession for engineers and a necessity
for poor people and racers. Cyclists in charge of their own destinies
do not need to swallow the choices of obsessives, underprivileged and
driven types. Utopia appears to cater for a class of cyclist probably
unknown on RBT until I arrived.
> i have a honking great cfrp one from
> salsa which turned the rear of my koga-miyata into something distinctly
> un-scary.
Sure. Magura have their own booster. And I might have to fit a booster
anyway because the special frame lock for these bikes is mounted on a
booster and I find other kinds of lock too inconvenient. The point
meanwhile is that the steel frame and the Magura rim brakes work well
together to give the class of rider at whom they are aimed a more
relaxed riding experience than discs or rollerbrakes mounted on very
stiff ali frames ever can.
It's an engineering solecism to posit only one possible end use or one
possible end user. it is a failure of imagination of lowest common
denominator engineers not to understand that a certain amount of flex
might be advantageous and desirable.
> and unfortunately, unless you have caliper brakes which press against
> themselves, you're going to have the same kind of problem with any kind
> of rear frame-levered brake on this bike, not just the hydraulics.
Aha! But, given the circumstances, then the hydraulic rim brake still
has certain advantages in contollability and also in maintenance over
cabled rim brakes (and over discs, whose pads I always wore out too
often, a PITA getting dirty hands just when one wants to ride).
In short, that frame and those brakes are there for reasons to do with
the customers' preferences, and a damn good thing too.
Andre Jute
The vanity of those who judge is well founded in hubris, of which no
shortage has ever been reported -- Al Marcy
Clive George
news:ba73bab3-3ce0-4cca...@40g2000prx.googlegroups.com...
>The manufacturer says they left them off to increase controllability.
Despite what your supplier says, you don't lose "controllability" by putting
a booster on. It doesn't turn into a rim-gripping monster - you still have
to apply the hand pressure. What they're doing is partly the equivalent of
shimano's "power modulators", and partly giving it a more conventional feel.
(The HS33 would actually be more controllable, due to the different gearing.
But it's a bit late for that.)
>Yeah, sure, I know the cheap shot from those who want to prove how
>clever they are is that "controllability" is the same thing as "not
>maximally efficient"
Is it a cheap shot if it's accurate?
If you've got anything like the experience you claim, and if you ride as you
claim (ride hard, brake hard), you really want to get those boosters on.
Don't worry about the different feel - you'll get used to it. Having the
stopping power available to you just after you've run through a puddle with
some diesel in and then having to do a hard stop is rather more important.
Bernhard Agthe
Andre Jute wrote:
> Yesterday I had a chance to try out the standard Magura HS11 hydraulic
> rim brakes on my Utopia Kranich in the wet.
Wet riding is always a little funny with rim brakes, do get the booster!
Actually I have HS33 (an older make, which means a different mount). It
has a booster and enables me to get almost full stopping power at the
first application of the brake on wet rims - by brute force. In fact
this brake is a hydraulic press (but only with the booster).
Really interesting is snow or in the wet near freezing point - the
brute-force approach does not work well then - apply the brake and
you'll notice increasing stopping power after the first full turn of the
wheel ;-)
Just a warning at the side line: Do exchange your brake pads - when they
wear off you won't be able to compensate wear by using the adjustment
screw (check your manual) and then you start to loose stopping power.
Also google for threads about which color pads to use, the "sports" pads
are said to behave better in wet and cold conditions (by some) while the
black ones are more "general-purpose-like"... Actually, did you sand
your brake pads' working surface? Otherwise you'll notice them
developing their full power after the surface has been used a little ;-)
> The Magura HS11 is fitted to the Utopia bikes without the booster,
No wonder it feels like a V-Brake ;-)
> Utopia claims for increased controllability. They're probably right. I
Haha - the real reason is here: not mounting the booster is cheaper!
Oh, beware: some bike shops will tell you that the "Evolution 2" Adapter
*is* the booster. But the Evo2 adapter is just the mounting plate
(between brake and frame). The booster is an extra part that does mount
on top of the brake.
...
> perfect conditions to lift the rear wheel a couple of millimetres. One
> would need really very strong hands to be in danger of going over the
> handlebars with the HS11.
Just as with any rim brake - without boosters the HS** is just that.
> As the price for their controllability and progressivity, the HS11
> offer the least stopping power of the three I rested. (It is too long
> since I owned traditional rim brakes to remember what they were like.)
> That applies even in the dry. In the wet, Shimano's roller brakes
> leave the HS11 for dead.
Not unless they're much worse than my old one - you can generally
compare HS** with good rim brakes. They should provide better braking
than roller brakes and somewhere about comparable to disk brakes.
Otherwise you should check your setup! In the wet, any hub-brake should
perform more consistently, natually.
> I ride hard and brake hard. The HS11 is good enough, just. In the same
> use, the Shimano 70/75 roller brakes, and the disc brake even more,
> require constant awareness if one isn't to lock them up with painful
> consequences. The HS11 are really a lot more controllable. In an
> emergency the HS11 in the wet might prove to be not good enough, but
> the roller brake and the disc might make the danger worse by locking
> up and sending the rider out of control. Swings and roundabouts.
Something about there... Actually on dry ground I can get my rear wheel
to lift during normal breaking, the HS** is that good. As I said, it is
about as good as any good rim or disk brake.
Because I never had roller brakes (coaster brakes only), I cannot say
much about them. But I'd expect them to behave well, up to the point of
good rim brakes. Even then, if a coaster brake handles decidedly
"binary" it might be a good idea to service the brake ;-) That's my
experience with coaster brakes ;-)
...
> is a different matter. There is a brake booster available for the HS11
> which is said to give greater stopping power at the price of less
> docility; the HS33 has a smaller cylinder and is more powerful still
> at the price of yet more controllability. Quite a few manufacturers
> and cyclists in Europe who can easily afford to fit discs instead fit
> the HS33 as a sporting/controllable/low maintenance alternative to
> discs.
Slowly, the HS** handles very "docile" with a booster. It just has a
higher "reserve" towards the maximum power ;-) And is easier on the
frame... Or, to phrase it differently, it retains the controllability
you mention, even if you mount the booster.
Have fun...
Clive George
news:gl74cg$67n$1...@daniel-new.mch.sbs.de...
> Actually I have HS33 (an older make, which means a different mount).
HS11 predates HS33, but that's not important right now :-)
> Just a warning at the side line: Do exchange your brake pads - when they
> wear off you won't be able to compensate wear by using the adjustment
> screw (check your manual) and then you start to loose stopping power.
Don't understand that bit though.
Bernhard Agthe
Clive George wrote:
> "Bernhard Agthe" <dark...@gmx.net> wrote in message
>> Actually I have HS33 (an older make, which means a different mount).
>
> HS11 predates HS33, but that's not important right now :-)
No, that's not the point. Over the years the actual brake mount changed.
The one I have is the one produced up to 2004, starting 2005 they use
the current Evo2 adapter.
The HS11 is the "cheaper" variant of the HS33, apart from the brake
lever and the booster they're identical:
HS33 has a metal brake lever with a wear-adjustment screw built as a
thumb-screw (no tool necessary) while the HS11 has a plastic lever and
you need an allen-key to operate the adjustment. The HS33 has (used to?)
the booster by default. That's all the difference, even the cylinders
inside the brake levers are the same. You can easily upgrade your HS11
to an HS33 model by swapping the levers and adding boosters.
>> Just a warning at the side line: Do exchange your brake pads - when they
>> wear off you won't be able to compensate wear by using the adjustment
>> screw (check your manual) and then you start to loose stopping power.
>
> Don't understand that bit though.
As the pads wear off, you operate the wear-adjustment screw to
compensate. The screw has a limited travel (naturally) and there is the
point where you cannot compensate any more. Even though your pads may
not be fully used up, you should exchange them when you notice the lever
"bottom-ing" ;-) That better?
Ciao..
Clive George
> Hi,
>
> Clive George wrote:
>> "Bernhard Agthe" <dark...@gmx.net> wrote in message
>>> Actually I have HS33 (an older make, which means a different mount).
>>
>> HS11 predates HS33, but that's not important right now :-)
>
> No, that's not the point. Over the years the actual brake mount changed.
> The one I have is the one produced up to 2004, starting 2005 they use
> the current Evo2 adapter.
>
> The HS11 is the "cheaper" variant of the HS33, apart from the brake
> lever and the booster they're identical:
>
> HS33 has a metal brake lever with a wear-adjustment screw built as a
> thumb-screw (no tool necessary) while the HS11 has a plastic lever and
> you need an allen-key to operate the adjustment. The HS33 has (used to?)
> the booster by default. That's all the difference, even the cylinders
> inside the brake levers are the same. You can easily upgrade your HS11
> to an HS33 model by swapping the levers and adding boosters.
HS33 has a smaller cylinder inside the brake lever, so different mechanical
advantage - more power. (see info on magura.de :-) )
>>> Just a warning at the side line: Do exchange your brake pads - when they
>>> wear off you won't be able to compensate wear by using the adjustment
>>> screw (check your manual) and then you start to loose stopping power.
>>
>> Don't understand that bit though.
>
> As the pads wear off, you operate the wear-adjustment screw to
> compensate. The screw has a limited travel (naturally) and there is the
> point where you cannot compensate any more. Even though your pads may
> not be fully used up, you should exchange them when you notice the lever
> "bottom-ing" ;-) That better?
Ah - you mean "change the brake pads when they wear out and stop working".
I'd have thought that would be reasonably obvious :-) You can actually
adjust them in their mounts so you get a full pads wear from the adjuster -
might be a bit harder with the HS33 though due to the different MA.
jim beam
> On Jan 21, 4:10�am, jim beam <retard-t...@bad.example.net> wrote:
>> Andre Jute wrote:
>>> Yesterday I had a chance to try out the standard Magura HS11 hydraulic
>>> rim brakes on my Utopia Kranich in the wet.
>>> The Magura HS11 is fitted to the Utopia bikes without the booster,
>>> Utopia claims for increased controllability. They're probably right. I
>>> tried the HS11 against Shimano 70/75 series roller brakes and 475
>>> series cable operated disc brakes. The discs are pretty much on/off.
>>> The roller brakes are more controllable but you still want to pay
>>> careful attention to what you do, or they will plant you on your face.
>>> The HS11, sans booster, can just barely be squeezed hard enough in
>>> perfect conditions to lift the rear wheel a couple of millimetres. One
>>> would need really very strong hands to be in danger of going over the
>>> handlebars with the HS11.
>>> As the price for their controllability and progressivity, the HS11
>>> offer the least stopping power of the three I rested. (It is too long
>>> since I owned traditional rim brakes to remember what they were like.)
>>> That applies even in the dry. In the wet, Shimano's roller brakes
>>> leave the HS11 for dead.
>> <snip>
>
> The text you snipped answered most of your points, at least by
> implication. First I'll restore the text, then I'll connect it to your
> points.
dude, it was /way/ too long. i didn't even read it.
everything flexes when loaded - by definition. but the question is, by
how much? the problem you're encountering is typical of "designers"
that just assume that the components they use on traditional caliper
brakes, i.e. light skinny rear stays, will work the same when laterally
loaded as opposed to axially loaded. it's simply failure to consider
the reality.
as for planes and suspension, both are designed to flex, and their
strains are known. skinny seat stays are not, and if that frame's
"designer" had even contemplated calculating strain, i'll eat my socks.
>
>> what you need is one of those horseshoe things that mounts between the
>> posts which reinforces the stays.
>
> The manufacturer says they left them off to increase controllability.
no, they discovered the problem after the fact. and rather than spend
time and money addressing the issue, they're simply sticking their head
in the sand and trying to bullshit their way out of it.
> Yeah, sure, I know the cheap shot from those who want to prove how
> clever they are is that "controllability" is the same thing as "not
> maximally efficient". I suspect that the people who buy these bikes
> are middle-aged and often buy them as a first bike. They're not
> interested in extracting maximum efficiency from every component, nor
> are they interested in sitting there hunched over in fear at what
> their own brakes will do to them if they squeeze them marginally too
> hard. Maximal efficiency is an obsession for engineers and a necessity
> for poor people and racers. Cyclists in charge of their own destinies
> do not need to swallow the choices of obsessives, underprivileged and
> driven types. Utopia appears to cater for a class of cyclist probably
> unknown on RBT until I arrived.
>
>> �i have a honking great cfrp one from
>> salsa which turned the rear of my koga-miyata into something distinctly
>> un-scary.
>
> Sure. Magura have their own booster.
because /they/, unlike the frame manufacturer, understand the issue!!!
> And I might have to fit a booster
> anyway because the special frame lock for these bikes is mounted on a
> booster and I find other kinds of lock too inconvenient. The point
> meanwhile is that the steel frame and the Magura rim brakes work well
> together to give the class of rider at whom they are aimed a more
> relaxed riding experience than discs or rollerbrakes mounted on very
> stiff ali frames ever can.
>
> It's an engineering solecism to posit only one possible end use or one
> possible end user. it is a failure of imagination of lowest common
> denominator engineers not to understand that a certain amount of flex
> might be advantageous and desirable.
>
>> and unfortunately, unless you have caliper brakes which press against
>> themselves, you're going to have the same kind of problem with any kind
>> of rear frame-levered brake on this bike, not just the hydraulics.
>
> Aha! But, given the circumstances, then the hydraulic rim brake still
> has certain advantages in contollability and also in maintenance over
> cabled rim brakes (and over discs, whose pads I always wore out too
> often, a PITA getting dirty hands just when one wants to ride).
hydraulics are great. but i wouldn't use them on a rim - there's no
advantage. just go for disks next time - i think they're awesome.
Clive George
> hydraulics are great. but i wouldn't use them on a rim - there's no
> advantage.
They beat cables when there's a long run - eg tandem rear brake, which
unlike on a solo can actually do something useful.
They're easier to maintain than cables, and IME more reliable - my 10yo ones
are pretty much untouched. Closed systems, mineral oil, so no fluid worries.
Linear pad movement - no need to adjust angle as pads wear out, and pad wear
adjustment is just one screw at the lever. Pads last longer than thin V
brake ones, and are beautifully easy to change.
If looking for a reliable flat bar utility bike like Andre's, they'd be high
on the list of desirables, purely because of the maintenance aspect. And
yes, I'm growing to hate V's.
Andre Jute
> Hi,
>
> Andre Jute wrote:
> > Yesterday I had a chance to try out the standard Magura HS11 hydraulic
> > rim brakes on my Utopia Kranich in the wet.
>
> Wet riding is always a little funny with rim brakes, do get the booster!
I'll probably have to fit the booster anyway, because the custom lock
I want to fit sits on a horseshoe which attaches to the brake mounts.
> Actually I have HS33 (an older make, which means a different mount). It
> has a booster and enables me to get almost full stopping power at the
> first application of the brake on wet rims - by brute force. In fact
> this brake is a hydraulic press (but only with the booster).
>
> Really interesting is snow or in the wet near freezing point - the
> brute-force approach does not work well then - apply the brake and
> you'll notice increasing stopping power after the first full turn of the
> wheel ;-)
Ha! This freezing spell is very rare here. My wheels are more likely
to see a constant mist of tiny droplets (called "a fine soft day") or
persistent light rain.
What you say squares well with the HS11 in an emergency stop recreated
at the place of a near accident stopping me from over 40kph in about
two meters longer than 70/75 series rollerbrakes.
> Just a warning at the side line: Do exchange your brake pads - when they
> wear off you won't be able to compensate wear by using the adjustment
> screw (check your manual) and then you start to loose stopping power.
> Also google for threads about which color pads to use, the "sports" pads
> are said to behave better in wet and cold conditions (by some) while the
> black ones are more "general-purpose-like"... Actually, did you sand
> your brake pads' working surface? Otherwise you'll notice them
> developing their full power after the surface has been used a little ;-)
Ah! I was wondering if I was just getting used to them or if they had
actually improved.
> > The Magura HS11 is fitted to the Utopia bikes without the booster,
>
> No wonder it feels like a V-Brake ;-)
>
> > Utopia claims for increased controllability. They're probably right. I
>
> Haha - the real reason is here: not mounting the booster is cheaper!
I'm prepared to give them the benefit of the doubt. I think everything
should be done which can be done to make bicycle brakes more user-
friendly.
> Oh, beware: some bike shops will tell you that the "Evolution 2" Adapter
> *is* the booster. But the Evo2 adapter is just the mounting plate
> (between brake and frame). The booster is an extra part that does mount
> on top of the brake.
>
> ...
>
> > perfect conditions to lift the rear wheel a couple of millimetres. One
> > would need really very strong hands to be in danger of going over the
> > handlebars with the HS11.
>
> Just as with any rim brake - without boosters the HS** is just that.
>
> > As the price for their controllability and progressivity, the HS11
> > offer the least stopping power of the three I rested. (It is too long
> > since I owned traditional rim brakes to remember what they were like.)
> > That applies even in the dry. In the wet, Shimano's roller brakes
> > leave the HS11 for dead.
>
> Not unless they're much worse than my old one - you can generally
> compare HS** with good rim brakes. They should provide better braking
> than roller brakes and somewhere about comparable to disk brakes.
Have you tried Shimano's 70/75 series roller brakes? They're
frighteningly powerful if you misuse them. I have bikes with
interchangeable wheels with disc and the 75, and, except for the 75
being less on-off than the disc, that is a spot more controllable,
they are pretty much equivalent in stopping power. In fact, the makers
of the bikes on which I have them promptly went back to fitting lesser
brakes, presumably because they decided their customers didn't need or
want that much braking.
We'll see when I get the frame lock which has a booster built in.
But you know, I took the HS11 as an experiment. I was quite prepared
to throw them off in order to fit discs. I'm still perfectly prepared
to replace them with HS33 if it turns out I need the extra 20 per cent
of braking ability, or with discs if it turns out on closer
acquaintance that the HS** are not quite good enough. It is difficult
perfectly to replicate the conditions of an emergency, so I'll find
out at the first real emergency whether controllability is bought at
too great a price.
> Have fun...
Andre Jute
http://members.lycos.co.uk/fiultra/Andre%20Jute's%20Utopia%20Kranich.pdf
Andre Jute
Then you have no idea of what I'm talking about, have you? As will
shortly become as clear as the fact that you have no idea either what
you're talking about, you're just blustering because bluster is what
you do.
So you say, Jimbo. I'm surprised bicycle manufacturers aren't lining
up to hire you as a consultant. But I'm afraid I'd rather put my faith
in Van Raam and in a frame that has hundreds of thousands of rough
miles under its belt. There's more bad news for you: see below where
you're eating your socks.
> as for planes and suspension, both are designed to flex, and their
> strains are known. skinny seat stays are not, and if that frame's
> "designer" had even contemplated calculating strain, i'll eat my socks.
Bon appetit.
http://www.utopia-velo.de/PDF/RadRatgeber_Nr_15.pdf and go to pp8-9.
Can you spell stress-test, Jimbo? How many bicycle manufacturers do
you know who do comparable testing?
Stop blustering, sonny, and do you homework before you try to lecture
me.
> >> what you need is one of those horseshoe things that mounts between the
> >> posts which reinforces the stays.
>
> > The manufacturer says they left them off to increase controllability.
>
> no, they discovered the problem after the fact. and rather than spend
> time and money addressing the issue, they're simply sticking their head
> in the sand and trying to bullshit their way out of it.
You really are an idiot, Jimbo. Did you ever, wherever you worked,
have anything to do with consumers? If the absence of the booster is a
problem, as you claim, rather than a solution for their customers,
they could long since have fitted the booster. Indeed, they offer it
as an extra to customers who want it.
Once more, do you homework before you bluster in public.
> > Yeah, sure, I know the cheap shot from those who want to prove how
> > clever they are is that "controllability" is the same thing as "not
> > maximally efficient". I suspect that the people who buy these bikes
> > are middle-aged and often buy them as a first bike. They're not
> > interested in extracting maximum efficiency from every component, nor
> > are they interested in sitting there hunched over in fear at what
> > their own brakes will do to them if they squeeze them marginally too
> > hard. Maximal efficiency is an obsession for engineers and a necessity
> > for poor people and racers. Cyclists in charge of their own destinies
> > do not need to swallow the choices of obsessives, underprivileged and
> > driven types. Utopia appears to cater for a class of cyclist probably
> > unknown on RBT until I arrived.
>
> >> i have a honking great cfrp one from
> >> salsa which turned the rear of my koga-miyata into something distinctly
> >> un-scary.
>
> > Sure. Magura have their own booster.
>
> because /they/, unlike the frame manufacturer, understand the issue!!!
Actually, if you'd done your homework, Jimbo, you would know that
Magura sells HS series hydraulic rim brakes without the booster on a
daily basis. Can't be too great an "issue" except in your mind, hmm?
> > And I might have to fit a booster
> > anyway because the special frame lock for these bikes is mounted on a
> > booster and I find other kinds of lock too inconvenient. The point
> > meanwhile is that the steel frame and the Magura rim brakes work well
> > together to give the class of rider at whom they are aimed a more
> > relaxed riding experience than discs or rollerbrakes mounted on very
> > stiff ali frames ever can.
>
> > It's an engineering solecism to posit only one possible end use or one
> > possible end user. it is a failure of imagination of lowest common
> > denominator engineers not to understand that a certain amount of flex
> > might be advantageous and desirable.
>
> >> and unfortunately, unless you have caliper brakes which press against
> >> themselves, you're going to have the same kind of problem with any kind
> >> of rear frame-levered brake on this bike, not just the hydraulics.
>
> > Aha! But, given the circumstances, then the hydraulic rim brake still
> > has certain advantages in contollability and also in maintenance over
> > cabled rim brakes (and over discs, whose pads I always wore out too
> > often, a PITA getting dirty hands just when one wants to ride).
>
> hydraulics are great. but i wouldn't use them on a rim - there's no
> advantage. just go for disks next time - i think they're awesome.
Man, I've gone off your advice. You shoot before you look.
> > In short, that frame and those brakes are there for reasons to do with
> > the customers' preferences, and a damn good thing too.
>
> > Andre Jute
> > The vanity of those who judge is well founded in hubris, of which no
> > shortage has ever been reported -- Al Marcy
You should have paid attention to my sigline before you embarrassed
yourself, Jimbo.
Andre Jute
Fingers well clear of the bricks
Tom Sherman
doing "headers" while riding. As Jobst Brandt likes to point out, going
over the bars from braking is mainly a function of the rider NOT bracing
his/her body properly. With proper bracing, an upright rider on dry
pavement can easily do deliberate "stoppies" and lift the rear wheel
well off the ground with no real danger of going over the bars.
--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll
Tom Sherman
Indeed. I have a bike where the lower stays could be seen to move
outward when the rear linear pull caliper was applied until I added a
"horseshoe" booster. Rear braking effectiveness went from "sorta
slowing" to being able to lock the rear wheel with a real hard squeeze
of the brake lever.
Tom Sherman
> Andre Jute wrote:
>> The text you snipped answered most of your points, at least by
>> implication. First I'll restore the text, then I'll connect it to your
>> points.
>
> dude, it was /way/ too long. i didn't even read it.
>
> [...]
> hydraulics are great. but i wouldn't use them on a rim - there's no
> advantage. just go for disks next time - i think they're awesome.
> [...]
No advantages in modulation over cable operated rim brakes? Not to
mention under certain conditions, the function of cable operated brakes
is degraded by contamination of the cables and housing, particularly by
frozen moisture.
Bernhard Agthe
Clive George wrote:
> HS33 has a smaller cylinder inside the brake lever, so different mechanical
> advantage - more power. (see info on magura.de :-) )
Ok, that's new - when I checked last, they were about the same ;-)
Anyway, you can still exchange the lever ;-)
> Ah - you mean "change the brake pads when they wear out and stop working".
> I'd have thought that would be reasonably obvious :-) You can actually
> adjust them in their mounts so you get a full pads wear from the adjuster -
> might be a bit harder with the HS33 though due to the different MA.
With the "older" mount I have it's actually not possible to adjust the
cylinders correctly on my frame - I would need a setting just between
the ones available ;-) So my "dead" brake pads might have a milimeter of
service life left. Even though, they've done well for 10.000 km, so
that's fine with me ;-)
Ciao..
Andre Jute
> So my "dead" brake pads might have a milimeter of
> service life left. Even though, they've done well for 10.000 km, so
> that's fine with me ;-)
Do we conclude:
1. You don't have an odometer on your bike and are guessing at round
numbers?
2. You are a scofflaw who routinely rides through stop signs and only
brakes to dismount?
3. You are an hyperbolist?
4. The HS** is really very economical with its brake blocks?
If 4 is true, that will be very good news indeed because I am fed up
to the gills with disc brakes chewing up pads at an expensive rate,
with the pads furthermore having to be replaced early lest they fade
just when racing downhill round the corner on a narrow lane you see
the cowpat of destiny silhouetted against the mother of all tractors,
filling the lane, with thorny hedgerows to either side. (1)
(1) Years ago, cycling with some fit friends along an up and down
little road near Butlerstown on the coast, I got to the head of the
line and hit a monstrous bump in the middle of the road for which they
had clearly been slowing down. My bike and I went flying over a short
blind dip in the road, in which a tractor was approaching us. Just
brushing the wheels across the roof of the tractor, I landed with a
bang on the far side, fortunately already up on the pedals, crunched
nothing and was gone down the next hill. A couple of years later the
tractor driver's wife ran into me in the library and told me he had
nightmares about the flying cyclist for a fortnight, then started
doubting he'd really seen me, it happened so quickly. My fellow
cyclists ragged me for years about going down in the folk memory as
The Flying Cyclist, like The Deer at the Gap. Oh, to be young and
reckless again.
Bernhard Agthe
Andre Jute wrote:
> On Jan 22, 8:51 am, Bernhard Agthe <dark2s...@gmx.net> wrote:
>> So my "dead" brake pads might have a milimeter of
>> service life left. Even though, they've done well for 10.000 km, so
>> that's fine with me ;-)
>
> Do we conclude:
> 1. You don't have an odometer on your bike and are guessing at round
> numbers?
Nope, my bike's odometer reads 9.8xx km right now (though I don't care
much) and the brake pads are still working (well, just about ceasing to
work). I did exchange them a few days ago.
So I figured, the round number is accurate enough ;-)
> 2. You are a scofflaw who routinely rides through stop signs and only
> brakes to dismount?
Mostly dense city traffic, occasionally larger bike trips, but then
mostly loaded. My brakes do see quite a bit of use. On the other hand, I
tend to break sharp, but short ;-) Really, my normal mode of stopping is
rather close to "emergency brake application" ;-)
> 3. You are an hyperbolist?
You need to count a 20kg bike as well as up to 20kg luggage ;-)
Sometimes a trailer with up to 30kg load ;-) I'd say I do have a reason
for using HS** brakes instead of old-fashioned cantilever ;-) For my
type of use and my riding style I do need good brakes ;-)
> 4. The HS** is really very economical with its brake blocks?
Well, it depends on your riding style and so on, but the brake blocks
give quite a bit of useful service life. They have a reputation for
being used up quickly in wet conditions though I did not really care.
Even then, it is a very simple thing to exchange the brake blocks,
washing your hands afterwards takes longer than the actual exchange ;-)
Have fun...
Clive George
> Hi,
>
> Clive George wrote:
>> HS33 has a smaller cylinder inside the brake lever, so different
>> mechanical
>> advantage - more power. (see info on magura.de :-) )
>
> Ok, that's new - when I checked last, they were about the same ;-)
Hmm - AFAIK it's always been the case - that was the advantage of the HS33,
but never mind :-)
> Anyway, you can still exchange the lever ;-)
Indeed.
Michael Press
Bernhard Agthe <dark...@gmx.net> wrote:
> Mostly dense city traffic, occasionally larger bike trips, but then
> mostly loaded. My brakes do see quite a bit of use. On the other hand, I
> tend to break sharp, but short ;-) Really, my normal mode of stopping is
> rather close to "emergency brake application" ;-)
That is how I apply brakes, unless I do not want to
alarm people crossing in front of me. It's good to
keep in touch with the limits of braking.
--
Michael Press
Dre
news:rubrum-9E8AEA....@news.sf.sbcglobal.net...
Excellent, I'm not the only one that does that :)
Sometimes when in the mood I like doing real hard stops and then finishing
off with a nice high endo! Yes I get some strange looks but thats part of
the fun, hehehe!
Cheers Dre
por...@gmail.com
HS66 racing bike lever brakes (ancient), and a Recumbent with HS33.
If you don't have a booster the braking will suck. You can see your
seat stays twist in on a steel bike without the booster.
If you have it, and you have the right pads, it is better than any
cantilever brake or V-brake I've used. This includes Dia Compe 986s,
Shimano cantis of all stripes, Tektro and Shimano V-brakes.
The stopping power is amazing on the recumbent, especially. I weight
160 and the recumbent 40, and you can lock up the front brake, but
that is hard to do, because the modulation is quite linear on
hydraulic brakes.
That is the biggest complaint I have about sidepulls. Their
modulation generally sucks. Whether that is because of cable casing
compression, or flexing in the arms, I dunno. Someone does.
I've had to overhaul the Maguras about once every five years. Once, I
lent my recumbent to a friend who weighs about 280 pounds and he blew
out the front hydraulic line. Of course, that was with no maintenance
for 10 years. Replacing lines is a snap.
Cheers, Rob
Andre Jute
> I have 3 bikes with Magura rim brakes, a MTB with HS33, a Tandem with
> HS66 racing bike lever brakes (ancient), and a Recumbent with HS33.
> If you don't have a booster the braking will suck. You can see your
> seat stays twist in on a steel bike without the booster.
Okay, I take your word for it. But the question remains, why does it
matter what your seat stays do? (Mine actually are braced right at the
brake, from the shape of the brace probably to resist brake side-
pressure.) The front brake does the work. All the rear brake is
required to do is lay the bike down in an emergency and for that you
can use any cheap old brake, you don't need hydraulic rim brakes with
or without the booster.
And the front brake is mounted on the natural booster of the thick-
wall, big-diameter, very stiff fork, right near its curvature. I think
you guys are spouting a normative case, what should be, rather than
the reality of what is achievable, which is probably marginal, since
whatever you can do in braking is limited by the coefficient of
friction between the road and the tyre.
> If you have it, and you have the right pads, it is better than any
> cantilever brake or V-brake I've used. This includes Dia Compe 986s,
> Shimano cantis of all stripes, Tektro and Shimano V-brakes.
>
> The stopping power is amazing on the recumbent, especially. I weight
> 160 and the recumbent 40, and you can lock up the front brake, but
> that is hard to do, because the modulation is quite linear on
> hydraulic brakes.
Now that impresses me, considering how little of your weight is on the
front wheel of a recumbent. I've locked my front Magura HS11 while I
was testing my handstrength and the limits of the brakes yesterday.
Since I don't know what the brakes will do and feel like with the
booster, I'll try it at the front. (I have to anyway; I think the
frame lock I want to fit requires the booster to have attachment
points...) However, I'm only fitting the booster at the front. I
*like* my rear brakes limp. Just about my only serious complaint about
the Shimano roller brakes was that at the rear they were too easily
locked up. Even if the booster only reduces controllability at the
rear marginally, I don't want that.
> That is the biggest complaint I have about sidepulls. Their
> modulation generally sucks. Whether that is because of cable casing
> compression, or flexing in the arms, I dunno. Someone does.
>
> I've had to overhaul the Maguras about once every five years.
Oops. I bought an expensive (33 Euro) kit to service Magura rim brakes
for delivery with the bike. Looks like it'll sit on the shelf for a
bit.
> Once, I
> lent my recumbent to a friend who weighs about 280 pounds and he blew
> out the front hydraulic line. Of course, that was with no maintenance
> for 10 years. Replacing lines is a snap.
>
> Cheers, Rob
Thanks for taking the time to send a detailed reply, Rob. These are my
first hydraulic rim brakes and, truth be told, I just took them to get
quick delivery, fully intending to chuck them off in favour of discs.
Now, with so many fans on RBT, and with good experience of the
hydraulic rim brakes on the bike even while the blocks are still
wearing in, I'm having second thoughts, and have just about decided to
keep the HS11.
Andre Jute
http://members.lycos.co.uk/fiultra/BICYCLE%20%26%20CYCLING.html
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:E_mdnT9mT_NpturU...@speakeasy.net...
>
>> hydraulics are great. but i wouldn't use them on a rim - there's no
>> advantage.
>
> They beat cables when there's a long run - eg tandem rear brake, which
> unlike on a solo can actually do something useful.
>
> They're easier to maintain than cables, and IME more reliable - my 10yo ones
> are pretty much untouched. Closed systems, mineral oil, so no fluid worries.
well, in automotive systems, periodic fluid changes are still specified.
> Linear pad movement - no need to adjust angle as pads wear out, and pad wear
> adjustment is just one screw at the lever.
ok, valid points. but i still don't see much point going hydraulic rim
vs hydraulic disk. i've always found wet and mud performance on disks
to be excellent - rim can be iffy, and wear pads [and rims] at an
incredible rate.
jim beam
the only people who deny or argue against these horseshoe things are
either people who have never used them or who have more modern aluminum
frames with big stiff rear stays that don't have the frame flex problem.
ignorance isn't an excuse.
Clive George
>> They're easier to maintain than cables, and IME more reliable - my 10yo
>> ones are pretty much untouched. Closed systems, mineral oil, so no fluid
>> worries.
>
>well, in automotive systems, periodic fluid changes are still specified.
Open systems need that. DOT fluid may be less stable than the mineral stuff
too.
>> Linear pad movement - no need to adjust angle as pads wear out, and pad
>> wear adjustment is just one screw at the lever.
>
> ok, valid points. but i still don't see much point going hydraulic rim vs
> hydraulic disk.
Drop bars - HS66 exists (though require work to obtain, s/h only these
days).
Frames/forks without disk mounts.
The newer MTB tandem has hydraulic disks, the older one HS11 or HS22 (not
sure which), the road tandem has HS66.
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:daidnVrWTaCOqebU...@speakeasy.net...
>
>>> They're easier to maintain than cables, and IME more reliable - my 10yo
>>> ones are pretty much untouched. Closed systems, mineral oil, so no fluid
>>> worries.
>> well, in automotive systems, periodic fluid changes are still specified.
>
> Open systems need that. DOT fluid may be less stable than the mineral stuff
> too.
the main advantage of glycol-ether fluid is that with mineral oil
fluids, moisture, as is inevitable to some degree, is not dissolved. it
can therefore form vapor or ice causing performance problems.
>
>>> Linear pad movement - no need to adjust angle as pads wear out, and pad
>>> wear adjustment is just one screw at the lever.
>> ok, valid points. but i still don't see much point going hydraulic rim vs
>> hydraulic disk.
>
> Drop bars - HS66 exists (though require work to obtain, s/h only these
> days).
> Frames/forks without disk mounts.
>
> The newer MTB tandem has hydraulic disks, the older one HS11 or HS22 (not
> sure which), the road tandem has HS66.
would it not be more satisfactory to retrofit the frame than continue
with the disadvantages of rim brakes?
Clive George
> the main advantage of glycol-ether fluid is that with mineral oil fluids,
> moisture, as is inevitable to some degree, is not dissolved. it can
> therefore form vapor or ice causing performance problems.
I can assure you that moisture isn't inevitable. My closed-system maguras
haven't been exposed to any for years - there's nowhere for it to get in.
Open system brakes are exposed to the atmosphere, so need to cope with that.
Re another thread - Citroens probably get away with it by having
significantly more fluid in the system, with a lot in continuous
circulation.
>>>> Linear pad movement - no need to adjust angle as pads wear out, and pad
>>>> wear adjustment is just one screw at the lever.
>>> ok, valid points. but i still don't see much point going hydraulic rim
>>> vs hydraulic disk.
>>
>> Drop bars - HS66 exists (though require work to obtain, s/h only these
>> days).
>> Frames/forks without disk mounts.
>>
>> The newer MTB tandem has hydraulic disks, the older one HS11 or HS22 (not
>> sure which), the road tandem has HS66.
>
> would it not be more satisfactory to retrofit the frame than continue with
> the disadvantages of rim brakes?
Short answer : no.
Al frame = no welding, any of the other mounts are just kludgy. And yes, I
have looked. For the MTB, ceramic-coated rims provide a reasonable
compromise.
And that still wouldn't help with the drop bar bike.
Question for you - why do you continue with rim brakes with their
disadvantages on any of your bikes?
Michael Press
"Dre" <andreas...@gmail.com> wrote:
> "Michael Press" <rub...@pacbell.net> wrote in message
> news:rubrum-9E8AEA....@news.sf.sbcglobal.net...
> > In article <gl9pn0$3sd$1...@daniel-new.mch.sbs.de>,
> > Bernhard Agthe <dark...@gmx.net> wrote:
> >
> >> Mostly dense city traffic, occasionally larger bike trips, but then
> >> mostly loaded. My brakes do see quite a bit of use. On the other hand, I
> >> tend to break sharp, but short ;-) Really, my normal mode of stopping is
> >> rather close to "emergency brake application" ;-)
> >
> > That is how I apply brakes, unless I do not want to
> > alarm people crossing in front of me. It's good to
> > keep in touch with the limits of braking.
>
> Excellent, I'm not the only one that does that :)
>
> Sometimes when in the mood I like doing real hard stops and then finishing
> off with a nice high endo! Yes I get some strange looks but thats part of
> the fun, hehehe!
Hi Yohhh, Silver!
--
Michael Press
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:9JqdncyxRKJ3H-bU...@speakeasy.net...
>
>> the main advantage of glycol-ether fluid is that with mineral oil fluids,
>> moisture, as is inevitable to some degree, is not dissolved. it can
>> therefore form vapor or ice causing performance problems.
>
> I can assure you that moisture isn't inevitable. My closed-system maguras
> haven't been exposed to any for years - there's nowhere for it to get in.
not true unfortunately - it diffuses in through seals and polymer tubing.
>
> Open system brakes are exposed to the atmosphere, so need to cope with that.
indeed - you need to change the fluid periodically. it's no more of an
inconvenience than changing a brake cable.
> Re another thread - Citroens probably get away with it by having
> significantly more fluid in the system, with a lot in continuous
> circulation.
how does circulation change moisture ingress??? all it does is move it
around!
>
>>>>> Linear pad movement - no need to adjust angle as pads wear out, and pad
>>>>> wear adjustment is just one screw at the lever.
>>>> ok, valid points. but i still don't see much point going hydraulic rim
>>>> vs hydraulic disk.
>>> Drop bars - HS66 exists (though require work to obtain, s/h only these
>>> days).
>>> Frames/forks without disk mounts.
>>>
>>> The newer MTB tandem has hydraulic disks, the older one HS11 or HS22 (not
>>> sure which), the road tandem has HS66.
>> would it not be more satisfactory to retrofit the frame than continue with
>> the disadvantages of rim brakes?
>
> Short answer : no.
>
> Al frame = no welding, any of the other mounts are just kludgy. And yes, I
> have looked. For the MTB, ceramic-coated rims provide a reasonable
> compromise.
actually, i like ceramics.
>
> And that still wouldn't help with the drop bar bike.
>
> Question for you - why do you continue with rim brakes with their
> disadvantages on any of your bikes?
i don't have rim brakes on my mtb, i'm hydraulic disk. i only have rim
brakes on my road bikes, and if we ever have a decent road hydraulic
disk brake alternative some day, i'll be happy to use it.
Clive George
> Clive George wrote:
>> "jim beam" <retar...@bad.example.net> wrote in message
>> news:9JqdncyxRKJ3H-bU...@speakeasy.net...
>>
>>> the main advantage of glycol-ether fluid is that with mineral oil
>>> fluids, moisture, as is inevitable to some degree, is not dissolved. it
>>> can therefore form vapor or ice causing performance problems.
>>
>> I can assure you that moisture isn't inevitable. My closed-system maguras
>> haven't been exposed to any for years - there's nowhere for it to get in.
>
> not true unfortunately - it diffuses in through seals and polymer tubing.
Hmm. To what sort of extent do you think? After 10 years, do you think there
will be a measurable amount of water in my closed-system brakes?
>> Re another thread - Citroens probably get away with it by having
>> significantly more fluid in the system, with a lot in continuous
>> circulation.
>
> how does circulation change moisture ingress??? all it does is move it
> around!
It means there's less chance of it pooling, and it gets the chance to come
back out into the air.
>>> would it not be more satisfactory to retrofit the frame than continue
>>> with the disadvantages of rim brakes?
...
>> Question for you - why do you continue with rim brakes with their
>> disadvantages on any of your bikes?
>
> i don't have rim brakes on my mtb, i'm hydraulic disk. i only have rim
> brakes on my road bikes, and if we ever have a decent road hydraulic disk
> brake alternative some day, i'll be happy to use it.
Right, so you agree that there are very good reasons to use rim brakes - eg
availability. Glad that's cleared up.
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:mJWdnT6ffrIzU-bU...@speakeasy.net...
>> Clive George wrote:
>>> "jim beam" <retar...@bad.example.net> wrote in message
>>> news:9JqdncyxRKJ3H-bU...@speakeasy.net...
>>>
>>>> the main advantage of glycol-ether fluid is that with mineral oil
>>>> fluids, moisture, as is inevitable to some degree, is not dissolved. it
>>>> can therefore form vapor or ice causing performance problems.
>>> I can assure you that moisture isn't inevitable. My closed-system maguras
>>> haven't been exposed to any for years - there's nowhere for it to get in.
>> not true unfortunately - it diffuses in through seals and polymer tubing.
>
> Hmm. To what sort of extent do you think? After 10 years, do you think there
> will be a measurable amount of water in my closed-system brakes?
it's not "closed".
http://en.wikipedia.org/wiki/Diffusion
moisture measurable? yes. obvious to the naked eye? debatable.
either way, a change doesn't hurt.
>
>>> Re another thread - Citroens probably get away with it by having
>>> significantly more fluid in the system, with a lot in continuous
>>> circulation.
>> how does circulation change moisture ingress??? all it does is move it
>> around!
>
> It means there's less chance of it pooling, and it gets the chance to come
> back out into the air.
diffusion doesn't work that way.
>
>>>> would it not be more satisfactory to retrofit the frame than continue
>>>> with the disadvantages of rim brakes?
> ...
>>> Question for you - why do you continue with rim brakes with their
>>> disadvantages on any of your bikes?
>> i don't have rim brakes on my mtb, i'm hydraulic disk. i only have rim
>> brakes on my road bikes, and if we ever have a decent road hydraulic disk
>> brake alternative some day, i'll be happy to use it.
>
> Right, so you agree that there are very good reasons to use rim brakes - eg
> availability. Glad that's cleared up.
i use rim brakes because they're the best actuation currently available
on road bikes. but they have their drawbacks as discussed, and as also
mentioned above, if i had a decent hydraulic road bike alternative for
disk, i'd use them instead. yes, you can use cable disk on a road bike,
and i've tried them, but i find cable disk modulation to be poor.
Clive George
> Clive George wrote:
>> "jim beam" <retar...@bad.example.net> wrote in message
>> news:mJWdnT6ffrIzU-bU...@speakeasy.net...
>>> Clive George wrote:
>>>> "jim beam" <retar...@bad.example.net> wrote in message
>>>> news:9JqdncyxRKJ3H-bU...@speakeasy.net...
>>>>
>>>>> the main advantage of glycol-ether fluid is that with mineral oil
>>>>> fluids, moisture, as is inevitable to some degree, is not dissolved.
>>>>> it can therefore form vapor or ice causing performance problems.
>>>> I can assure you that moisture isn't inevitable. My closed-system
>>>> maguras haven't been exposed to any for years - there's nowhere for it
>>>> to get in.
>>> not true unfortunately - it diffuses in through seals and polymer
>>> tubing.
>>
>> Hmm. To what sort of extent do you think? After 10 years, do you think
>> there will be a measurable amount of water in my closed-system brakes?
>
> it's not "closed".
>
> http://en.wikipedia.org/wiki/Diffusion
>
> moisture measurable? yes. obvious to the naked eye? debatable. either
> way, a change doesn't hurt.
Actually, it does. Leaving all my nice pipes sealed as they are means
there's far less chance of getting air, water or other grot into the system.
Opening it up also increases the chance of getting those nice seals wrong on
reassembly.
What would happen if I did have any water in my system? Well, freezing is a
possibility - but that would need more than the microscopic amounts you're
talking about to make any difference. Boiling to vapour - more likely. What
would happen in that case? Bear in mind it's a closed system, not an open
one like car brakes. This means that the brakes would be pushed on, rather
than the car failure of the fluid being replaced by compressible gas. And
I've never had anything remotely close to that even with brakes hot enough
to cause problems with tyres, so I think I'm probably ok.
And I still reckon the amount of water you might get through diffusion is
far too tiny to worry about. Show me appropriate counter-examples and I
might reconsider, but for now, I'm going with the general feeling that my
system is to all intents and purposes closed.
>>>> Re another thread - Citroens probably get away with it by having
>>>> significantly more fluid in the system, with a lot in continuous
>>>> circulation.
>>> how does circulation change moisture ingress??? all it does is move it
>>> around!
>>
>> It means there's less chance of it pooling, and it gets the chance to
>> come back out into the air.
>
> diffusion doesn't work that way.
Yeah. What's the prime source of water in brake fluid? Diffusion or the open
bit at the top?
(Is diffusion the new fatigue?)
jim beam
no, it doesn't hurt. you have bleed nipples expressly for this purpose
and you don't need to strip the system in any way. besides, the fluids
have seal conditioners and it helps to refresh periodically.
>
> What would happen if I did have any water in my system? Well, freezing is a
> possibility - but that would need more than the microscopic amounts you're
> talking about to make any difference. Boiling to vapour - more likely. What
> would happen in that case?
you lose braking - you pull the lever and it just sinks. now, that's an
extreme example, but it can happen.
> Bear in mind it's a closed system, not an open
> one like car brakes.
thats not true - the seals and polymer tubes allow diffusion. indeed,
with car systems, the primary source of ingress is through the flex hoses.
> This means that the brakes would be pushed on, rather
> than the car failure of the fluid being replaced by compressible gas.
i don't understand what you're trying to say there. fluids with gas in
them are more compressible than those without. doesn't make a
difference what that gas is - air, water vapor, whatever.
> And
> I've never had anything remotely close to that even with brakes hot enough
> to cause problems with tyres, so I think I'm probably ok.
it's good that you don't get to the limit, but you still want the
extreme performance option available if you need it. people only
discovered this stuff at the edge of the performance envelope, not
tooling about.
>
> And I still reckon the amount of water you might get through diffusion is
> far too tiny to worry about. Show me appropriate counter-examples and I
> might reconsider, but for now, I'm going with the general feeling that my
> system is to all intents and purposes closed.
it's not "closed". technically, it's really hard to truly "close" any
system. the diffusion rate is slow, and for shorter periods, it's
negligible. but dude, 10 years is 10 years.
>
>>>>> Re another thread - Citroens probably get away with it by having
>>>>> significantly more fluid in the system, with a lot in continuous
>>>>> circulation.
>>>> how does circulation change moisture ingress??? all it does is move it
>>>> around!
>>> It means there's less chance of it pooling, and it gets the chance to
>>> come back out into the air.
>> diffusion doesn't work that way.
>
> Yeah. What's the prime source of water in brake fluid? Diffusion or the open
> bit at the top?
diffusion through the polymer tubes.
>
> (Is diffusion the new fatigue?)
no, it's ancient history. you studied an example in high school biology
if you did the sugar solution/semi-permeable membrane experiment.
Andrew Price
<cl...@xxxx-x.fsnet.co.uk> wrote:
>> diffusion doesn't work that way.
>
>Yeah. What's the prime source of water in brake fluid? Diffusion or the open
>bit at the top?
>
>(Is diffusion the new fatigue?)
Who cares? He obviously knows nothing about Magura brakes. I've been
using them for years with no problems at all.
Ben C
[...]
> What would happen if I did have any water in my system? Well, freezing
> is a possibility - but that would need more than the microscopic
> amounts you're talking about to make any difference. Boiling to vapour
> - more likely. What would happen in that case? Bear in mind it's a
> closed system, not an open one like car brakes. This means that the
> brakes would be pushed on, rather than the car failure of the fluid
> being replaced by compressible gas.
Why not? If some of the fluid becomes vapour, then it will be
compressible. When the brakes are actually on in a car there's no path
back from the calipers etc. to the reservoir on top of the master
cylinder-- it's effectively just as closed as the system on your bike.
But the pedal goes spongy because you can compress the vapour.
Clive George
Uh-oh. Jim, you've wandered into that which you don't know. How about you
check what Magura suggest is a suitable schedule for bleeding and fluid
replacement for their rim brakes? (hint - they say that you should _never_
need to do it).
>> What would happen if I did have any water in my system? Well, freezing is
>> a possibility - but that would need more than the microscopic amounts
>> you're talking about to make any difference. Boiling to vapour - more
>> likely. What would happen in that case?
>
> you lose braking - you pull the lever and it just sinks. now, that's an
> extreme example, but it can happen.
>
>> Bear in mind it's a closed system, not an open one like car brakes.
>
> thats not true - the seals and polymer tubes allow diffusion. indeed,
> with car systems, the primary source of ingress is through the flex hoses.
I think you don't understand what a closed system is in the context of
brakes. A closed brake system is really simple - pistons at each end. An
open one has the ability to let fluid into or out of the system to a
reservoir. Some disk brakes are closed, but they discovered if it gets hot
everything just locks up (BTDT - hope C2 on the front of a borrowed tandem -
not as far as locking up, but it did start rubbing). So you have an open
system, which compensates for the differing volumes/densities. The rim
brakes don't allow much heat transfer to the cylinders, so don't suffer in
the same way.
>> This means that the brakes would be pushed on, rather than the car
>> failure of the fluid being replaced by compressible gas.
>
> i don't understand what you're trying to say there. fluids with gas in
> them are more compressible than those without. doesn't make a difference
> what that gas is - air, water vapor, whatever.
I know. But you don't. Start with a closed system with x ml of fluid. Add y
ml of vapour - what will the net effect be? Yes, it's a growth in volume,
and the brakes will go on. In an open system, the fluid gets replaced by
vapour. In a closed system, it's additive.
>> And I've never had anything remotely close to that even with brakes hot
>> enough to cause problems with tyres, so I think I'm probably ok.
>
> it's good that you don't get to the limit, but you still want the extreme
> performance option available if you need it. people only discovered this
> stuff at the edge of the performance envelope, not tooling about.
May be worth considering what I wrote. I _am_ at the edge of the performance
envelope for rim brakes. (I'm on a tandem, on very steep hills, with a nasty
amount of braking).
>> And I still reckon the amount of water you might get through diffusion is
>> far too tiny to worry about. Show me appropriate counter-examples and I
>> might reconsider, but for now, I'm going with the general feeling that my
>> system is to all intents and purposes closed.
>
> it's not "closed". technically, it's really hard to truly "close" any
> system. the diffusion rate is slow, and for shorter periods, it's
> negligible. but dude, 10 years is 10 years.
And the diffusion rate is tiny if it's there at all. Magura don't say
"replace after 10 years", they say "Don't replace".
>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>> circulation.
>>>>> how does circulation change moisture ingress??? all it does is move
>>>>> it around!
>>>> It means there's less chance of it pooling, and it gets the chance to
>>>> come back out into the air.
>>> diffusion doesn't work that way.
>>
>> Yeah. What's the prime source of water in brake fluid? Diffusion or the
>> open bit at the top?
>
> diffusion through the polymer tubes.
Y'know, I'm not sure I actually believe you there. For a conventional
system, maybe, but since the fluid isn't keen on grabbing hold of water in a
LHM based system, there's not nearly the impetus for diffusion to do
anything significant.
>> (Is diffusion the new fatigue?)
>
> no, it's ancient history. you studied an example in high school biology
> if you did the sugar solution/semi-permeable membrane experiment.
Whoosh.
Clive George
news:slrngnpnuv....@bowser.marioworld...
That's not what actually happens. The pedal goes spongy after it's been
released and the gas pressure has forced fluid out into the reservoir.
If you actually held the brakes on and got the fluid to boil you'd feel lot
of back-pressure, and the brakes would come on. Were you to have the
presence of mind to not release the pedal at that point, and weren't in a
situation where you'd release the pedal anyway (eg after the bend), then
you'd be in a closed system, but otherwise you've let the pressure go.
Think about the volumes involved in the closed system, and the positions of
the master and slave cylinders at the various points. It should be clear to
you.
Ben C
> "Ben C" <spam...@spam.eggs> wrote in message
> news:slrngnpnuv....@bowser.marioworld...
>> On 2009-01-25, Clive George <cl...@xxxx-x.fsnet.co.uk> wrote:
>> [...]
>>> What would happen if I did have any water in my system? Well, freezing
>>> is a possibility - but that would need more than the microscopic
>>> amounts you're talking about to make any difference. Boiling to vapour
>>> - more likely. What would happen in that case? Bear in mind it's a
>>> closed system, not an open one like car brakes. This means that the
>>> brakes would be pushed on, rather than the car failure of the fluid
>>> being replaced by compressible gas.
>>
>> Why not? If some of the fluid becomes vapour, then it will be
>> compressible. When the brakes are actually on in a car there's no path
>> back from the calipers etc. to the reservoir on top of the master
>> cylinder-- it's effectively just as closed as the system on your bike.
>> But the pedal goes spongy because you can compress the vapour.
>
> That's not what actually happens. The pedal goes spongy after it's been
> released and the gas pressure has forced fluid out into the reservoir.
You may be right. It's some time since I had the brakes go spongy on a
car and I don't remember the details except that I changed all the fluid
the next day.
I do remember that they stayed spongy for a little while. I stopped and
let it all cool down for a while, then they OK again and I drove home
carefully.
> If you actually held the brakes on and got the fluid to boil you'd feel lot
> of back-pressure, and the brakes would come on. Were you to have the
> presence of mind to not release the pedal at that point, and weren't in a
> situation where you'd release the pedal anyway (eg after the bend), then
> you'd be in a closed system, but otherwise you've let the pressure go.
>
> Think about the volumes involved in the closed system, and the positions of
> the master and slave cylinders at the various points. It should be clear to
> you.
Well, it's not clear to me a priori that bubbles of vapour suddenly
appearing in a closed system wouldn't compress and result in sponginess.
It might be that when the brakes are on the fluid is under too much
pressure to boil-- it only boils when you release the brakes (also
pushing fluid back into the reservoir as you say) and then compresses
the next time you apply the brakes.
But I can see that a closed system might result in binding brakes if
things got a bit hot or even if it was just a hot day. That's presumably
why you have an open system-- so it can renormalize itself every times
you release the brakes.
Clive George
> Well, it's not clear to me a priori that bubbles of vapour suddenly
> appearing in a closed system wouldn't compress and result in sponginess.
The vapour is much less dense than the fluid, so the volume of fluid remains
essentially unchanged. If you're already braking, there's a volume X between
the cylinders. Introduce more volume, whether gas or liquid, and either the
pedal or brake cylinders need to move - and the brake cylinders are already
bound by the disk/rim. The pressure has to go up if it boils, and hence the
pressure on your foot. But I think you've got this here:
> It might be that when the brakes are on the fluid is under too much
> pressure to boil-- it only boils when you release the brakes (also
> pushing fluid back into the reservoir as you say) and then compresses
> the next time you apply the brakes.
Seems a fair mechanism to me.
> But I can see that a closed system might result in binding brakes if
> things got a bit hot or even if it was just a hot day. That's presumably
> why you have an open system-- so it can renormalize itself every times
> you release the brakes.
Yup, that's just it. With disc brakes, it definitely happens - I took a
tandem with Hope C2 brakes down a hill, and the bite point was moving really
obviously, and I think the brake was starting to bind. The rim brakes don't
suffer this - at a guess, the thick rubber pads insulate better than the
thin <whateveritis> ones, and of course the peak temperatures are lower.
jim beam
> "Ben C" <spam...@spam.eggs> wrote in message
> news:slrngnprt9....@bowser.marioworld...
>
>> Well, it's not clear to me a priori that bubbles of vapour suddenly
>> appearing in a closed system wouldn't compress and result in sponginess.
>
> The vapour is much less dense than the fluid, so the volume of fluid remains
> essentially unchanged. If you're already braking, there's a volume X between
> the cylinders. Introduce more volume, whether gas or liquid, and either the
> pedal or brake cylinders need to move - and the brake cylinders are already
> bound by the disk/rim. The pressure has to go up if it boils, and hence the
> pressure on your foot. But I think you've got this here:
no - see what i say below. with a correctly adjusted system, this
shouldn't happen.
>
>> It might be that when the brakes are on the fluid is under too much
>> pressure to boil-- it only boils when you release the brakes (also
>> pushing fluid back into the reservoir as you say) and then compresses
>> the next time you apply the brakes.
>
> Seems a fair mechanism to me.
>
>> But I can see that a closed system might result in binding brakes if
>> things got a bit hot or even if it was just a hot day. That's presumably
>> why you have an open system-- so it can renormalize itself every times
>> you release the brakes.
>
> Yup, that's just it. With disc brakes, it definitely happens - I took a
> tandem with Hope C2 brakes down a hill, and the bite point was moving really
> obviously, and I think the brake was starting to bind.
that's a different issue - hydraulic brakes need to have a return
circuit in the master cylinder. if that is "adjusted" closed, as fluid
warms, they can bind. happens in cars after master cylinder replacement
if the brake pedal is not adjusted correctly.
http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html
> The rim brakes don't
> suffer this - at a guess, the thick rubber pads insulate better than the
> thin <whateveritis> ones, and of course the peak temperatures are lower.
nope - see above.
jim beam
do they project a life of 10 years? i doubt that!
>
>>> What would happen if I did have any water in my system? Well, freezing is
>>> a possibility - but that would need more than the microscopic amounts
>>> you're talking about to make any difference. Boiling to vapour - more
>>> likely. What would happen in that case?
>> you lose braking - you pull the lever and it just sinks. now, that's an
>> extreme example, but it can happen.
>>
>>> Bear in mind it's a closed system, not an open one like car brakes.
>> thats not true - the seals and polymer tubes allow diffusion. indeed,
>> with car systems, the primary source of ingress is through the flex hoses.
>
> I think you don't understand what a closed system is in the context of
> brakes. A closed brake system is really simple - pistons at each end. An
> open one has the ability to let fluid into or out of the system to a
> reservoir. Some disk brakes are closed, but they discovered if it gets hot
> everything just locks up (BTDT - hope C2 on the front of a borrowed tandem -
> not as far as locking up, but it did start rubbing). So you have an open
> system, which compensates for the differing volumes/densities. The rim
> brakes don't allow much heat transfer to the cylinders, so don't suffer in
> the same way.
no hydraulic brake system should be "closed" as you describe. either
the master cylinder is absent an equalization port or it's been adjusted
wrong. besides, you're confusing "closed" with no port and "closed"
with not being susceptible to atmosphere - two completely different things.
>
>>> This means that the brakes would be pushed on, rather than the car
>>> failure of the fluid being replaced by compressible gas.
>> i don't understand what you're trying to say there. fluids with gas in
>> them are more compressible than those without. doesn't make a difference
>> what that gas is - air, water vapor, whatever.
>
> I know. But you don't. Start with a closed system with x ml of fluid. Add y
> ml of vapour - what will the net effect be? Yes, it's a growth in volume,
> and the brakes will go on. In an open system, the fluid gets replaced by
> vapour. In a closed system, it's additive.
yes, but unless magura are dumb enough to not provide an equalization
port, you have an "open" [by your definition] system.
>
>>> And I've never had anything remotely close to that even with brakes hot
>>> enough to cause problems with tyres, so I think I'm probably ok.
>> it's good that you don't get to the limit, but you still want the extreme
>> performance option available if you need it. people only discovered this
>> stuff at the edge of the performance envelope, not tooling about.
>
> May be worth considering what I wrote. I _am_ at the edge of the performance
> envelope for rim brakes. (I'm on a tandem, on very steep hills, with a nasty
> amount of braking).
then you should worry about changing the fluid!
>
>>> And I still reckon the amount of water you might get through diffusion is
>>> far too tiny to worry about. Show me appropriate counter-examples and I
>>> might reconsider, but for now, I'm going with the general feeling that my
>>> system is to all intents and purposes closed.
>> it's not "closed". technically, it's really hard to truly "close" any
>> system. the diffusion rate is slow, and for shorter periods, it's
>> negligible. but dude, 10 years is 10 years.
>
> And the diffusion rate is tiny if it's there at all. Magura don't say
> "replace after 10 years", they say "Don't replace".
do they project a usage life of 10 years? automotive hydraulics with
mineral oil are typically around 5 years. there's no reason a bike
should be different, just because it doesn't have a combustion engine to
stop.
>
>>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>>> circulation.
>>>>>> how does circulation change moisture ingress??? all it does is move
>>>>>> it around!
>>>>> It means there's less chance of it pooling, and it gets the chance to
>>>>> come back out into the air.
>>>> diffusion doesn't work that way.
>>> Yeah. What's the prime source of water in brake fluid? Diffusion or the
>>> open bit at the top?
>> diffusion through the polymer tubes.
>
> Y'know, I'm not sure I actually believe you there.
that's evident!
> For a conventional
> system, maybe, but since the fluid isn't keen on grabbing hold of water in a
> LHM based system, there's not nearly the impetus for diffusion to do
> anything significant.
don't take my word for it - bother to read the link i gave you and click
around a bit!
>
>>> (Is diffusion the new fatigue?)
>> no, it's ancient history. you studied an example in high school biology
>> if you did the sugar solution/semi-permeable membrane experiment.
>
> Whoosh.
dude, being unaware of basic science is one thing. but dismissing
something you don't know about as irrelevant when you have insufficient
information to make that decision is just plain stupid.
Clive George
> Clive George wrote:
>> "Ben C" <spam...@spam.eggs> wrote in message
>> news:slrngnprt9....@bowser.marioworld...
>>
>>> Well, it's not clear to me a priori that bubbles of vapour suddenly
>>> appearing in a closed system wouldn't compress and result in sponginess.
>>
>> The vapour is much less dense than the fluid, so the volume of fluid
>> remains essentially unchanged. If you're already braking, there's a
>> volume X between the cylinders. Introduce more volume, whether gas or
>> liquid, and either the pedal or brake cylinders need to move - and the
>> brake cylinders are already bound by the disk/rim. The pressure has to go
>> up if it boils, and hence the pressure on your foot. But I think you've
>> got this here:
>
> no - see what i say below. with a correctly adjusted system, this
> shouldn't happen.
Ahem. You don't know what you're talking about.
>>> It might be that when the brakes are on the fluid is under too much
>>> pressure to boil-- it only boils when you release the brakes (also
>>> pushing fluid back into the reservoir as you say) and then compresses
>>> the next time you apply the brakes.
>>
>> Seems a fair mechanism to me.
>>
>>> But I can see that a closed system might result in binding brakes if
>>> things got a bit hot or even if it was just a hot day. That's presumably
>>> why you have an open system-- so it can renormalize itself every times
>>> you release the brakes.
>>
>> Yup, that's just it. With disc brakes, it definitely happens - I took a
>> tandem with Hope C2 brakes down a hill, and the bite point was moving
>> really obviously, and I think the brake was starting to bind.
>
> that's a different issue - hydraulic brakes need to have a return circuit
> in the master cylinder. if that is "adjusted" closed, as fluid warms,
> they can bind. happens in cars after master cylinder replacement if the
> brake pedal is not adjusted correctly.
>
> http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html
Yes, and? Doesn't apply to the closed system brakes I'm talking about.
Magura rim brakes are closed, Hope C2 are closed, Hope O2 are open - hence
the name.
>> The rim brakes don't suffer this - at a guess, the thick rubber pads
>> insulate better than the thin <whateveritis> ones, and of course the peak
>> temperatures are lower.
>
> nope - see above.
When you understand the basics of the systems we're talking about, maybe
then it would be acceptable for you to say that. Until you do though,
anything you write is liable to be nonsense.
Clive George
Well, they've been making them for at least 18 years, and the manuals
haven't changed in that time. Your doubts are misplaced.
>>>> What would happen if I did have any water in my system? Well, freezing
>>>> is a possibility - but that would need more than the microscopic
>>>> amounts you're talking about to make any difference. Boiling to
>>>> vapour - more likely. What would happen in that case?
>>> you lose braking - you pull the lever and it just sinks. now, that's an
>>> extreme example, but it can happen.
>>>
>>>> Bear in mind it's a closed system, not an open one like car brakes.
>>> thats not true - the seals and polymer tubes allow diffusion. indeed,
>>> with car systems, the primary source of ingress is through the flex
>>> hoses.
>>
>> I think you don't understand what a closed system is in the context of
>> brakes. A closed brake system is really simple - pistons at each end. An
>> open one has the ability to let fluid into or out of the system to a
>> reservoir. Some disk brakes are closed, but they discovered if it gets
>> hot everything just locks up (BTDT - hope C2 on the front of a borrowed
>> tandem - not as far as locking up, but it did start rubbing). So you have
>> an open system, which compensates for the differing volumes/densities.
>> The rim brakes don't allow much heat transfer to the cylinders, so don't
>> suffer in the same way.
>
> no hydraulic brake system should be "closed" as you describe. either the
> master cylinder is absent an equalization port or it's been adjusted
> wrong. besides, you're confusing "closed" with no port and "closed" with
> not being susceptible to atmosphere - two completely different things.
Jim - How much will it take you to accept that it is a closed system, no
"equalization port". I've been hinting at this throughout this thread, yet
you continute to miss it.
>>>> This means that the brakes would be pushed on, rather than the car
>>>> failure of the fluid being replaced by compressible gas.
>>> i don't understand what you're trying to say there. fluids with gas in
>>> them are more compressible than those without. doesn't make a
>>> difference what that gas is - air, water vapor, whatever.
>>
>> I know. But you don't. Start with a closed system with x ml of fluid. Add
>> y ml of vapour - what will the net effect be? Yes, it's a growth in
>> volume, and the brakes will go on. In an open system, the fluid gets
>> replaced by vapour. In a closed system, it's additive.
>
> yes, but unless magura are dumb enough to not provide an equalization
> port, you have an "open" [by your definition] system.
See above. "Dumb"? Well, the brakes actually work very well.
>>>> And I've never had anything remotely close to that even with brakes hot
>>>> enough to cause problems with tyres, so I think I'm probably ok.
>>> it's good that you don't get to the limit, but you still want the
>>> extreme performance option available if you need it. people only
>>> discovered this stuff at the edge of the performance envelope, not
>>> tooling about.
>>
>> May be worth considering what I wrote. I _am_ at the edge of the
>> performance envelope for rim brakes. (I'm on a tandem, on very steep
>> hills, with a nasty amount of braking).
>
> then you should worry about changing the fluid!
Magura don't seem to think so. Why should I believe you over them when you
don't even know the basic layout of the brakes you're trying to discuss?
>>>> And I still reckon the amount of water you might get through diffusion
>>>> is far too tiny to worry about. Show me appropriate counter-examples
>>>> and I might reconsider, but for now, I'm going with the general feeling
>>>> that my system is to all intents and purposes closed.
>>> it's not "closed". technically, it's really hard to truly "close" any
>>> system. the diffusion rate is slow, and for shorter periods, it's
>>> negligible. but dude, 10 years is 10 years.
>>
>> And the diffusion rate is tiny if it's there at all. Magura don't say
>> "replace after 10 years", they say "Don't replace".
>
> do they project a usage life of 10 years? automotive hydraulics with
> mineral oil are typically around 5 years. there's no reason a bike should
> be different, just because it doesn't have a combustion engine to stop.
Closed system. That's the most important difference. I know you're
struggling to accept it, but you really do need to do so.
>>>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>>>> circulation.
>>>>>>> how does circulation change moisture ingress??? all it does is move
>>>>>>> it around!
>>>>>> It means there's less chance of it pooling, and it gets the chance to
>>>>>> come back out into the air.
>>>>> diffusion doesn't work that way.
>>>> Yeah. What's the prime source of water in brake fluid? Diffusion or the
>>>> open bit at the top?
>>> diffusion through the polymer tubes.
>>
>> Y'know, I'm not sure I actually believe you there.
>
> that's evident!
>
>
>> For a conventional system, maybe, but since the fluid isn't keen on
>> grabbing hold of water in a LHM based system, there's not nearly the
>> impetus for diffusion to do anything significant.
>
> don't take my word for it - bother to read the link i gave you and click
> around a bit!
I did, nothing pertinent came up. You may be assuming more than you ought...
>>>> (Is diffusion the new fatigue?)
>>> no, it's ancient history. you studied an example in high school biology
>>> if you did the sugar solution/semi-permeable membrane experiment.
>>
>> Whoosh.
>
> dude, being unaware of basic science is one thing. but dismissing
> something you don't know about as irrelevant when you have insufficient
> information to make that decision is just plain stupid.
Keep it up...
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:FNGdne3fsorssuDU...@speakeasy.net...
>> Clive George wrote:
>>> "Ben C" <spam...@spam.eggs> wrote in message
>>> news:slrngnprt9....@bowser.marioworld...
>>>
>>>> Well, it's not clear to me a priori that bubbles of vapour suddenly
>>>> appearing in a closed system wouldn't compress and result in sponginess.
>>> The vapour is much less dense than the fluid, so the volume of fluid
>>> remains essentially unchanged. If you're already braking, there's a
>>> volume X between the cylinders. Introduce more volume, whether gas or
>>> liquid, and either the pedal or brake cylinders need to move - and the
>>> brake cylinders are already bound by the disk/rim. The pressure has to go
>>> up if it boils, and hence the pressure on your foot. But I think you've
>>> got this here:
>> no - see what i say below. with a correctly adjusted system, this
>> shouldn't happen.
>
> Ahem. You don't know what you're talking about.
yes i do - equalization ports are braking hydraulics 101.
>
>>>> It might be that when the brakes are on the fluid is under too much
>>>> pressure to boil-- it only boils when you release the brakes (also
>>>> pushing fluid back into the reservoir as you say) and then compresses
>>>> the next time you apply the brakes.
>>> Seems a fair mechanism to me.
>>>
>>>> But I can see that a closed system might result in binding brakes if
>>>> things got a bit hot or even if it was just a hot day. That's presumably
>>>> why you have an open system-- so it can renormalize itself every times
>>>> you release the brakes.
>>> Yup, that's just it. With disc brakes, it definitely happens - I took a
>>> tandem with Hope C2 brakes down a hill, and the bite point was moving
>>> really obviously, and I think the brake was starting to bind.
>> that's a different issue - hydraulic brakes need to have a return circuit
>> in the master cylinder. if that is "adjusted" closed, as fluid warms,
>> they can bind. happens in cars after master cylinder replacement if the
>> brake pedal is not adjusted correctly.
>>
>> http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html
>
> Yes, and? Doesn't apply to the closed system brakes I'm talking about.
> Magura rim brakes are closed, Hope C2 are closed, Hope O2 are open - hence
> the name.
you're not listening to what i said. and you apparently didn't read the
link.
>
>>> The rim brakes don't suffer this - at a guess, the thick rubber pads
>>> insulate better than the thin <whateveritis> ones, and of course the peak
>>> temperatures are lower.
>> nope - see above.
>
> When you understand the basics of the systems we're talking about, maybe
> then it would be acceptable for you to say that. Until you do though,
> anything you write is liable to be nonsense.
some people, you can write it plain and simple, but they just don't
understand.
jim beam
no, you're making presumption about longevity.
if there is no equalization port, why are you continuing to use such a
retarded system??? to have one is hydraulics 101. you read the master
cylinder link, right?
and when /i/ was talking "open" and "closed" originally, i was talking
about the ability for moisture to enter the system - that is nothing to
do with equalization.
>
>>>>> This means that the brakes would be pushed on, rather than the car
>>>>> failure of the fluid being replaced by compressible gas.
>>>> i don't understand what you're trying to say there. fluids with gas in
>>>> them are more compressible than those without. doesn't make a
>>>> difference what that gas is - air, water vapor, whatever.
>>> I know. But you don't. Start with a closed system with x ml of fluid. Add
>>> y ml of vapour - what will the net effect be? Yes, it's a growth in
>>> volume, and the brakes will go on. In an open system, the fluid gets
>>> replaced by vapour. In a closed system, it's additive.
>> yes, but unless magura are dumb enough to not provide an equalization
>> port, you have an "open" [by your definition] system.
>
> See above. "Dumb"? Well, the brakes actually work very well.
sure - and they bind when hot because there is no equalization port!
>
>>>>> And I've never had anything remotely close to that even with brakes hot
>>>>> enough to cause problems with tyres, so I think I'm probably ok.
>>>> it's good that you don't get to the limit, but you still want the
>>>> extreme performance option available if you need it. people only
>>>> discovered this stuff at the edge of the performance envelope, not
>>>> tooling about.
>>> May be worth considering what I wrote. I _am_ at the edge of the
>>> performance envelope for rim brakes. (I'm on a tandem, on very steep
>>> hills, with a nasty amount of braking).
>> then you should worry about changing the fluid!
>
> Magura don't seem to think so. Why should I believe you over them when you
> don't even know the basic layout of the brakes you're trying to discuss?
but i do. seems you just don't want to hear it!
>
>>>>> And I still reckon the amount of water you might get through diffusion
>>>>> is far too tiny to worry about. Show me appropriate counter-examples
>>>>> and I might reconsider, but for now, I'm going with the general feeling
>>>>> that my system is to all intents and purposes closed.
>>>> it's not "closed". technically, it's really hard to truly "close" any
>>>> system. the diffusion rate is slow, and for shorter periods, it's
>>>> negligible. but dude, 10 years is 10 years.
>>> And the diffusion rate is tiny if it's there at all. Magura don't say
>>> "replace after 10 years", they say "Don't replace".
>> do they project a usage life of 10 years? automotive hydraulics with
>> mineral oil are typically around 5 years. there's no reason a bike should
>> be different, just because it doesn't have a combustion engine to stop.
>
> Closed system. That's the most important difference. I know you're
> struggling to accept it, but you really do need to do so.
it's not closed to diffusion - how many more times?
>
>>>>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>>>>> circulation.
>>>>>>>> how does circulation change moisture ingress??? all it does is move
>>>>>>>> it around!
>>>>>>> It means there's less chance of it pooling, and it gets the chance to
>>>>>>> come back out into the air.
>>>>>> diffusion doesn't work that way.
>>>>> Yeah. What's the prime source of water in brake fluid? Diffusion or the
>>>>> open bit at the top?
>>>> diffusion through the polymer tubes.
>>> Y'know, I'm not sure I actually believe you there.
>> that's evident!
>>
>>
>>> For a conventional system, maybe, but since the fluid isn't keen on
>>> grabbing hold of water in a LHM based system, there's not nearly the
>>> impetus for diffusion to do anything significant.
>> don't take my word for it - bother to read the link i gave you and click
>> around a bit!
>
> I did, nothing pertinent came up. You may be assuming more than you ought...
nothing pertinent came up??? then you don't understand what you're
looking at!
>
>>>>> (Is diffusion the new fatigue?)
>>>> no, it's ancient history. you studied an example in high school biology
>>>> if you did the sugar solution/semi-permeable membrane experiment.
>>> Whoosh.
>> dude, being unaware of basic science is one thing. but dismissing
>> something you don't know about as irrelevant when you have insufficient
>> information to make that decision is just plain stupid.
>
> Keep it up...
see above.
Ben C
[...]
>>>>> But I can see that a closed system might result in binding brakes if
>>>>> things got a bit hot or even if it was just a hot day. That's presumably
>>>>> why you have an open system-- so it can renormalize itself every times
>>>>> you release the brakes.
>>>> Yup, that's just it. With disc brakes, it definitely happens - I took a
>>>> tandem with Hope C2 brakes down a hill, and the bite point was moving
>>>> really obviously, and I think the brake was starting to bind.
>>> that's a different issue - hydraulic brakes need to have a return circuit
>>> in the master cylinder. if that is "adjusted" closed, as fluid warms,
>>> they can bind. happens in cars after master cylinder replacement if the
>>> brake pedal is not adjusted correctly.
>>>
>>> http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html
>>
>> Yes, and? Doesn't apply to the closed system brakes I'm talking about.
>> Magura rim brakes are closed, Hope C2 are closed, Hope O2 are open - hence
>> the name.
>
> you're not listening to what i said. and you apparently didn't read the
> link.
The link describes what we've been calling an "open" system. I'm less
clear on the layout of a "closed" system-- is it just the same as an
open system, with a little bit of air at the top, but just with the
reservoir cap glued on; or is there absolutely no air in there at all?
Clive George
No, the manufacturers are. Do you think they'd explicitly state in their
manuals "Don't change the fluid" if they didn't mean it?
An important thing about learning is to know when it's wrong. Empirical
evidence demonstrates that the closed system works for magura rim brakes,
and indeed works very well. (The same can't be said for the closed disk
brakes, but many people find they're sufficient.)
So the basic knowledge you posess about hydraulics clearly isn't sufficient.
And FWIW it's not a "retarded system", it's a "retarding system" - that's
what brakes do.
> you read the master cylinder link, right?
No, because I didn't need to. (checks). It's told me nothing new.
> and when /i/ was talking "open" and "closed" originally, i was talking
> about the ability for moisture to enter the system - that is nothing to do
> with equalization.
The fact that you don't understand the terminology is your problem, not
mine. But closed has less routes for moisture to enter.
>>>>>> This means that the brakes would be pushed on, rather than the car
>>>>>> failure of the fluid being replaced by compressible gas.
>>>>> i don't understand what you're trying to say there. fluids with gas
>>>>> in them are more compressible than those without. doesn't make a
>>>>> difference what that gas is - air, water vapor, whatever.
>>>> I know. But you don't. Start with a closed system with x ml of fluid.
>>>> Add y ml of vapour - what will the net effect be? Yes, it's a growth in
>>>> volume, and the brakes will go on. In an open system, the fluid gets
>>>> replaced by vapour. In a closed system, it's additive.
>>> yes, but unless magura are dumb enough to not provide an equalization
>>> port, you have an "open" [by your definition] system.
>>
>> See above. "Dumb"? Well, the brakes actually work very well.
>
> sure - and they bind when hot because there is no equalization port!
You know they bind when they're hot do you? You've experienced that? Hint -
they don't. Which tells us they don't need an equalisation port. Magura
aren't _that_ dim - they'd have had their asses sued off by now if the'd got
that one wrong.
>>>>>> And I've never had anything remotely close to that even with brakes
>>>>>> hot enough to cause problems with tyres, so I think I'm probably ok.
>>>>> it's good that you don't get to the limit, but you still want the
>>>>> extreme performance option available if you need it. people only
>>>>> discovered this stuff at the edge of the performance envelope, not
>>>>> tooling about.
>>>> May be worth considering what I wrote. I _am_ at the edge of the
>>>> performance envelope for rim brakes. (I'm on a tandem, on very steep
>>>> hills, with a nasty amount of braking).
>>> then you should worry about changing the fluid!
>>
>> Magura don't seem to think so. Why should I believe you over them when
>> you don't even know the basic layout of the brakes you're trying to
>> discuss?
>
> but i do. seems you just don't want to hear it!
For how many posts did you assume they had a reservoir and equalisation
port?
>>>>>> And I still reckon the amount of water you might get through
>>>>>> diffusion is far too tiny to worry about. Show me appropriate
>>>>>> counter-examples and I might reconsider, but for now, I'm going with
>>>>>> the general feeling that my system is to all intents and purposes
>>>>>> closed.
>>>>> it's not "closed". technically, it's really hard to truly "close" any
>>>>> system. the diffusion rate is slow, and for shorter periods, it's
>>>>> negligible. but dude, 10 years is 10 years.
>>>> And the diffusion rate is tiny if it's there at all. Magura don't say
>>>> "replace after 10 years", they say "Don't replace".
>>> do they project a usage life of 10 years? automotive hydraulics with
>>> mineral oil are typically around 5 years. there's no reason a bike
>>> should be different, just because it doesn't have a combustion engine to
>>> stop.
>>
>> Closed system. That's the most important difference. I know you're
>> struggling to accept it, but you really do need to do so.
>
> it's not closed to diffusion - how many more times?
And any diffusion effect is _tiny_ - unmeasurable. How many more times? Post
the numbers if you don't believe me.
>>>>>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>>>>>> circulation.
>>>>>>>>> how does circulation change moisture ingress??? all it does is
>>>>>>>>> move it around!
>>>>>>>> It means there's less chance of it pooling, and it gets the chance
>>>>>>>> to come back out into the air.
>>>>>>> diffusion doesn't work that way.
>>>>>> Yeah. What's the prime source of water in brake fluid? Diffusion or
>>>>>> the open bit at the top?
>>>>> diffusion through the polymer tubes.
>>>> Y'know, I'm not sure I actually believe you there.
>>> that's evident!
>>>
>>>
>>>> For a conventional system, maybe, but since the fluid isn't keen on
>>>> grabbing hold of water in a LHM based system, there's not nearly the
>>>> impetus for diffusion to do anything significant.
>>> don't take my word for it - bother to read the link i gave you and click
>>> around a bit!
>>
>> I did, nothing pertinent came up. You may be assuming more than you
>> ought...
>
> nothing pertinent came up??? then you don't understand what you're
> looking at!
Go on, give me a specific link to water diffusion in magura brake lines.
Widen it to mineral oil brake lines if you want.
>>>>>> (Is diffusion the new fatigue?)
>>>>> no, it's ancient history. you studied an example in high school
>>>>> biology if you did the sugar solution/semi-permeable membrane
>>>>> experiment.
>>>> Whoosh.
>>> dude, being unaware of basic science is one thing. but dismissing
>>> something you don't know about as irrelevant when you have insufficient
>>> information to make that decision is just plain stupid.
>>
>> Keep it up...
>
> see above.
Pretending to know stuff you clearly don't is even worse.
Ben C
> "jim beam" <retar...@bad.example.net> wrote in message
>> sure - and they bind when hot because there is no equalization port!
>
> You know they bind when they're hot do you? You've experienced that? Hint -
> they don't. Which tells us they don't need an equalisation port. Magura
> aren't _that_ dim - they'd have had their asses sued off by now if the'd got
> that one wrong.
Presumably the reason they don't bind is there's a bit of a gap between
the pads and rim anyway. That gap can just get a bit smaller if things
get hotter.
But with a disk brake the pad is right up next to the disk-- no return
spring or anything.
Clive George
That's pretty much it. Actually the older rim brakes have enormous rim
clearance - far more than even somebody who is slack about keeping wheels
true needs. With HS33, they traded off a bit of that clearance for power, by
making the master cylinder a little smaller. (Now if only they'd done the
same for the HS66, and kept on making them..)
Rim brakes can get away with this because they're enormous circles so you
don't need nearly as much force on the pads to get a decent effect. If their
rim brakes had the same MA as disks, apart from the drag on
less-than-perfect rims and the utter pain in setting them up, things would
get very messy as soon as you applied them :-)
Michael Press
jim beam <retar...@bad.example.net> wrote:
> dude, being unaware of basic science is one thing. but dismissing
> something you don't know about as irrelevant when you have insufficient
> information to make that decision is just plain stupid.
This is the sweet spot in a jim beam diatribe.
--
Michael Press
jim beam
> Ben C <spam...@spam.eggs> considered Mon, 26 Jan 2009 02:34:54 -0600
> Since the system is closed, why would you need a reservoir?
er, to allow for an equalization port and thermal expansion - you know,
so your brakes don't lock on when they get hot?
jim beam
> jim beam <retar...@bad.example.net> considered Sun, 25 Jan 2009
> true for open systems - closed systems do not need equalisation, since
> the volume doesn't change by more than is caused by heating - which is
> why you only use them in situations where comparitively little heat is
> transferred to the fluid (like rim brakes which have small, thick pads
> instead of large thin ones).
but clive complains that his brakes bind when the fluid gets hot on long
tandem descents. thus he needs and "open" system. and it's notable
that magura don't make "closed" systems any more.
>> and when /i/ was talking "open" and "closed" originally, i was talking
>> about the ability for moisture to enter the system - that is nothing to
>> do with equalization.
>>
>>
>>>>>>> This means that the brakes would be pushed on, rather than the car
>>>>>>> failure of the fluid being replaced by compressible gas.
>>>>>> i don't understand what you're trying to say there. fluids with gas in
>>>>>> them are more compressible than those without. doesn't make a
>>>>>> difference what that gas is - air, water vapor, whatever.
>>>>> I know. But you don't. Start with a closed system with x ml of fluid. Add
>>>>> y ml of vapour - what will the net effect be? Yes, it's a growth in
>>>>> volume, and the brakes will go on. In an open system, the fluid gets
>>>>> replaced by vapour. In a closed system, it's additive.
>>>> yes, but unless magura are dumb enough to not provide an equalization
>>>> port, you have an "open" [by your definition] system.
>>> See above. "Dumb"? Well, the brakes actually work very well.
>> sure - and they bind when hot because there is no equalization port!
>>
> That's not what he wrote.
>>>>>>> And I've never had anything remotely close to that even with brakes hot
>>>>>>> enough to cause problems with tyres, so I think I'm probably ok.
>>>>>> it's good that you don't get to the limit, but you still want the
>>>>>> extreme performance option available if you need it. people only
>>>>>> discovered this stuff at the edge of the performance envelope, not
>>>>>> tooling about.
>>>>> May be worth considering what I wrote. I _am_ at the edge of the
>>>>> performance envelope for rim brakes. (I'm on a tandem, on very steep
>>>>> hills, with a nasty amount of braking).
>>>> then you should worry about changing the fluid!
>>> Magura don't seem to think so. Why should I believe you over them when you
>>> don't even know the basic layout of the brakes you're trying to discuss?
>> but i do. seems you just don't want to hear it!
>>
> You haven't yet demonstrated any knowledge of a closed hydraulic
> braking system.
clive said:
"do you think there will be a measurable amount of water in my
closed-system brakes?"
and
"Open system brakes are exposed to the atmosphere"
first, "open" systems, as in those with equalizer ports, are no more
expose to atmosphere than is he "closed" system - the reservoir is sealed.
and can they absorb water? absolutely - all hydraulic systems can do
that is they have seals or polymer hoses. use some nice detergent in
that hydraulic oil for lubrication and wear particle suspension and
you're off to the races.
>>>>>>> And I still reckon the amount of water you might get through diffusion
>>>>>>> is far too tiny to worry about. Show me appropriate counter-examples
>>>>>>> and I might reconsider, but for now, I'm going with the general feeling
>>>>>>> that my system is to all intents and purposes closed.
>>>>>> it's not "closed". technically, it's really hard to truly "close" any
>>>>>> system. the diffusion rate is slow, and for shorter periods, it's
>>>>>> negligible. but dude, 10 years is 10 years.
>>>>> And the diffusion rate is tiny if it's there at all. Magura don't say
>>>>> "replace after 10 years", they say "Don't replace".
>>>> do they project a usage life of 10 years? automotive hydraulics with
>>>> mineral oil are typically around 5 years. there's no reason a bike should
>>>> be different, just because it doesn't have a combustion engine to stop.
>>> Closed system. That's the most important difference. I know you're
>>> struggling to accept it, but you really do need to do so.
>> it's not closed to diffusion - how many more times?
>>
> And how much diffusion do you think is likely to occur into a system
> which contains non-hygroscopic fluid?
it could be the same amount - it depends on the thermodynamics of the
oil/water combination.
>>>>>>>>>>> Re another thread - Citroens probably get away with it by having
>>>>>>>>>>> significantly more fluid in the system, with a lot in continuous
>>>>>>>>>>> circulation.
>>>>>>>>>> how does circulation change moisture ingress??? all it does is move
>>>>>>>>>> it around!
>>>>>>>>> It means there's less chance of it pooling, and it gets the chance to
>>>>>>>>> come back out into the air.
>>>>>>>> diffusion doesn't work that way.
>>>>>>> Yeah. What's the prime source of water in brake fluid? Diffusion or the
>>>>>>> open bit at the top?
>>>>>> diffusion through the polymer tubes.
>>>>> Y'know, I'm not sure I actually believe you there.
>>>> that's evident!
>>>>
>>>>
>>>>> For a conventional system, maybe, but since the fluid isn't keen on
>>>>> grabbing hold of water in a LHM based system, there's not nearly the
>>>>> impetus for diffusion to do anything significant.
>>>> don't take my word for it - bother to read the link i gave you and click
>>>> around a bit!
>>> I did, nothing pertinent came up. You may be assuming more than you ought...
>> nothing pertinent came up??? then you don't understand what you're
>> looking at!
>>
> Nothing pertinent to _closed_ systems, which it seems you don't
> understand.
see above. "closed" hydraulics don't mean "impermeable to atmospheric
diffusion" and "open" hydraulics don't mean "open to atmosphere". my
shimano xt hydraulics are [sensibly] "open", but "sealed" to atmosphere.
Clive George
>> In a closed system, there is no air at all, and no "reservoir".
>> Since the system is closed, why would you need a reservoir?
>
> er, to allow for an equalization port and thermal expansion - you know, so
> your brakes don't lock on when they get hot?
In the way that Magura rim brakes don't? Yet they don't have a reservoir,
air, equalisation port - how can this be possible? Fortunately those
fiendish Germans ignored their copy of jb's hydraulics 101 text, and instead
attended the advanced course and worked out what could actually be done.
Clive George
> but clive complains that his brakes bind when the fluid gets hot on long
> tandem descents. thus he needs and "open" system. and it's notable that
> magura don't make "closed" systems any more.
Um, I never said that at all. You do seem to have been struggling with basic
comprehension throughout this thread.
Magura do still make closed system brakes - their rim brakes are the example
we're talking about.
I mentioned a set of Hope C2s which did bind - they're disk brakes, not rim
brakes. I'd not use closed on disks, but the owner of that bike didn't have
a problem with them.
>> And how much diffusion do you think is likely to occur into a system
>> which contains non-hygroscopic fluid?
>
> it could be the same amount - it depends on the thermodynamics of the
> oil/water combination.
Right, so we're into the realms of what you don't know. Tell you what, how
about I trust the manufacturer's manual rather than your FUD - sound fair?
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:HPCdnaOtwoXrFePU...@speakeasy.net...
>
>> but clive complains that his brakes bind when the fluid gets hot on long
>> tandem descents. thus he needs and "open" system. and it's notable that
>> magura don't make "closed" systems any more.
>
> Um, I never said that at all. You do seem to have been struggling with basic
> comprehension throughout this thread.
>
> Magura do still make closed system brakes - their rim brakes are the example
> we're talking about.
>
> I mentioned a set of Hope C2s which did bind - they're disk brakes, not rim
> brakes. I'd not use closed on disks, but the owner of that bike didn't have
> a problem with them.
so, are "closed" systems fundamentally flawed or are they not???
totally disregarding getting confused about atmospheric exposure and
diffusion of course.
>
>>> And how much diffusion do you think is likely to occur into a system
>>> which contains non-hygroscopic fluid?
>> it could be the same amount - it depends on the thermodynamics of the
>> oil/water combination.
>
> Right, so we're into the realms of what you don't know. Tell you what, how
> about I trust the manufacturer's manual rather than your FUD - sound fair?
i don't carry all little numbers around in my head when there are data
tables. what /i/ bother remembering is principles of science, something
that sadly seems to escape some people.
jim beam
so that's why they changed their designs to "open" systems then?
Ben C
> Phil W Lee wrote:
>> Ben C <spam...@spam.eggs> considered Mon, 26 Jan 2009 02:34:54 -0600
>>> The link describes what we've been calling an "open" system. I'm less
>>> clear on the layout of a "closed" system-- is it just the same as an
>>> open system, with a little bit of air at the top, but just with the
>>> reservoir cap glued on; or is there absolutely no air in there at all?
>>
>> In a closed system, there is no air at all, and no "reservoir".
>> Since the system is closed, why would you need a reservoir?
>
> er, to allow for an equalization port and thermal expansion - you know,
> so your brakes don't lock on when they get hot?
So there must be some air at the top? Or a plunger that moves up and
down, or something to allow the whole system's total volume to change?
Ben C
> see above. "closed" hydraulics don't mean "impermeable to atmospheric
> diffusion" and "open" hydraulics don't mean "open to atmosphere". my
> shimano xt hydraulics are [sensibly] "open", but "sealed" to atmosphere.
Is there not some way for air to enter through the reservoir cap? I
think on a car there is, because as the pads wear, the fluid level goes
down quite a bit (more fluid sitting in the slave cylinders). Without
some ventilation you'd have too much of a vacuum.
If you need to disconnect a brake hose on a car because you're taking
the hub off or something, but you don't want to change the brake fluid,
you take the master cylinder cap off, put a plastic bag over the top,
and then screw the cap back on to really make it sealed. That way all
the brake fluid doesn't drip out. You also tie up the end of the hose
but that's to stop crap getting in.
Chalo
Motorcycle brake reservoirs use a concentrically corrugated rubber
diaphragm that also serves as a gasket. When the system loses fluid
volume through seepage or leaks, the diaphragm sucks down under the
structural lid.
Chalo
Andre Jute
>and it's notable that magura don't make "closed" systems any more.
Once more you haven't done your homework, Jimbo. Once more you're
spouting total crap. You must be running out of socks to eat.
Magura, FYI, makes and sells closed hydraulic brake systems today as
they have for many years. See http://www.magura.com/english/frameset/frameset.htm
for three current models of Magura closed hydraulic brake systems.
You'd be less of a tiresome internet contrarian, Jimbo, if you
occasionally did your homework before spouting off.
Andre Jute
My homework is done. May I help you with yours?
Clive George
> Clive George wrote:
>> "jim beam" <retar...@bad.example.net> wrote in message
>> news:HPCdnaOtwoXrFePU...@speakeasy.net...
>>
>>> but clive complains that his brakes bind when the fluid gets hot on long
>>> tandem descents. thus he needs and "open" system. and it's notable
>>> that magura don't make "closed" systems any more.
>>
>> Um, I never said that at all. You do seem to have been struggling with
>> basic comprehension throughout this thread.
>>
>> Magura do still make closed system brakes - their rim brakes are the
>> example we're talking about.
>>
>> I mentioned a set of Hope C2s which did bind - they're disk brakes, not
>> rim brakes. I'd not use closed on disks, but the owner of that bike
>> didn't have a problem with them.
>
> so, are "closed" systems fundamentally flawed or are they not???
The answer is "Not necessarily". They definitely work very well in certain
contexts. In others, they're a bad idea.
Do you agree with that now?
Clive George
Jim, they haven't changed to "open" for their rim brakes. A closed system
will be easier to manufacture and more reliable, so provided it is used in
an appropriate context it will be the correct solution.
jim beam
> On 2009-01-27, jim beam <retar...@bad.example.net> wrote:
> [...]
>> see above. "closed" hydraulics don't mean "impermeable to atmospheric
>> diffusion" and "open" hydraulics don't mean "open to atmosphere". my
>> shimano xt hydraulics are [sensibly] "open", but "sealed" to atmosphere.
>
> Is there not some way for air to enter through the reservoir cap? I
> think on a car there is, because as the pads wear, the fluid level goes
> down quite a bit (more fluid sitting in the slave cylinders). Without
> some ventilation you'd have too much of a vacuum.
it depends on the system. on my shimano xt disk hydraulics, the
reservoirs use a flexible rubber diaphragm that moves with the liquid
surface level.
>
> If you need to disconnect a brake hose on a car because you're taking
> the hub off or something, but you don't want to change the brake fluid,
> you take the master cylinder cap off, put a plastic bag over the top,
> and then screw the cap back on to really make it sealed. That way all
> the brake fluid doesn't drip out. You also tie up the end of the hose
> but that's to stop crap getting in.
best way to deal with that on cars is to pinch the rubber flex hose.
jim beam
ok andre, i can't be bothered to spend ages digging through every single
product detail of any particular manufacturer's website. mea culpa.
but if you think that means, contrary to basic physics, that "closed"
systems /aren't/ subject to binding when the brake fluid heats and
expands, you'd be /way/ off base.
jim beam
but we have a known context - and no, i can't see the point. for the
sake of some minor extra drilling and a rubber diaphragm, to, er,
"overlook" a basic problem that's been known forever seems utterly
bizarre - i simply can't understand why anyone would cut corners like that.
jim beam
> "jim beam" <retar...@bad.example.net> wrote in message
> news:0emdnSiK2ayoBOPU...@speakeasy.net...
>> Clive George wrote:
>>> "jim beam" <retar...@bad.example.net> wrote in message
>>> news:csadne-fPJ-8GOPU...@speakeasy.net...
>>>
>>>>> In a closed system, there is no air at all, and no "reservoir".
>>>>> Since the system is closed, why would you need a reservoir?
>>>> er, to allow for an equalization port and thermal expansion - you know,
>>>> so your brakes don't lock on when they get hot?
>>> In the way that Magura rim brakes don't? Yet they don't have a reservoir,
>>> air, equalisation port - how can this be possible? Fortunately those
>>> fiendish Germans ignored their copy of jb's hydraulics 101 text, and
>>> instead attended the advanced course and worked out what could actually
>>> be done.
>> so that's why they changed their designs to "open" systems then?
>
> Jim, they haven't changed to "open" for their rim brakes. A closed system
> will be easier to manufacture
cheaper by the cost of some drilling and a rubber diaphragm - hardly
material costs.
> and more reliable, so provided it is used in
> an appropriate context it will be the correct solution.
a non-braking context where heating doesn't occur!
jim beam
same for shimano hydraulics. not exactly complicated or expensive.
Clive George
How many times does this have to be pointed out to you? Magura rim brakes do
NOT suffer binding. Nothing like it. They're a properly engineered system,
and as such work well.
It's not as simple as "minor extra drilling and a rubber diaphragm" either.
Compare the closed-system rim brake levers with open ones. And I still can't
work out how to do an open system on a drop bar lever either without having
the complication of a remote reservoir - but HS66 levers are really simple.
It's not that the problem you're obsessing about has been overlooked, or
ignored - what's happened is the system has been designed to take it into
account. And it works.
I know you're having a great deal of trouble reconciling your theory with
practice here. I know there are psychological barriers which prevent people
from admitting they've made a mistake. But you've really got to get over
them - when presented with evidence that something works, you need to update
your theoretical model to cope with it, not sit there denying it's possible.
Ben C
> Ben C wrote:
>> On 2009-01-27, jim beam <retar...@bad.example.net> wrote:
>> [...]
>>> see above. "closed" hydraulics don't mean "impermeable to atmospheric
>>> diffusion" and "open" hydraulics don't mean "open to atmosphere". my
>>> shimano xt hydraulics are [sensibly] "open", but "sealed" to atmosphere.
>>
>> Is there not some way for air to enter through the reservoir cap? I
>> think on a car there is, because as the pads wear, the fluid level goes
>> down quite a bit (more fluid sitting in the slave cylinders). Without
>> some ventilation you'd have too much of a vacuum.
>
> it depends on the system. on my shimano xt disk hydraulics, the
> reservoirs use a flexible rubber diaphragm that moves with the liquid
> surface level.
Like the motorbikes Chalo mentioned.
Do the Shimano brakes describe themselves as "closed" or "open", or
neither?
Ben C
> Ben C <spam...@spam.eggs> considered Tue, 27 Jan 2009 02:43:36 -0600
> the perfect time to write:
>
>>[...]
>>> see above. "closed" hydraulics don't mean "impermeable to atmospheric
>>> diffusion" and "open" hydraulics don't mean "open to atmosphere". my
>>> shimano xt hydraulics are [sensibly] "open", but "sealed" to atmosphere.
>>
>>Is there not some way for air to enter through the reservoir cap? I
>>think on a car there is, because as the pads wear, the fluid level goes
>>down quite a bit (more fluid sitting in the slave cylinders). Without
>>some ventilation you'd have too much of a vacuum.
>
> diaphragm style seal in the reservoir.
>>
>>If you need to disconnect a brake hose on a car because you're taking
>>the hub off or something, but you don't want to change the brake fluid,
>>you take the master cylinder cap off, put a plastic bag over the top,
>>and then screw the cap back on to really make it sealed. That way all
>>the brake fluid doesn't drip out. You also tie up the end of the hose
>>but that's to stop crap getting in.
>
> usually that seals between the diaphragm and the vent in the cap,
> preventing the diaphragm from moving.
If you have a diaphragm on your open system, I guess there's no reason
why water would get into it any more than into a closed system in the
sense that the Magura rim brake is (i.e. no reservoir and no diaphragm).
Clive George
news:slrngnuc0c....@bowser.marioworld...
> If you have a diaphragm on your open system, I guess there's no reason
> why water would get into it any more than into a closed system in the
> sense that the Magura rim brake is (i.e. no reservoir and no diaphragm).
And shimano use mineral oil rather than conventional brake fluid IIRC.
Chalo
>
> Chalo wrote:
>
> >Motorcycle brake reservoirs use a concentrically corrugated rubber
> >diaphragm that also serves as a gasket. When the system loses fluid
> >volume through seepage or leaks, the diaphragm sucks down under the
> >structural lid.
>
Open to what?
The reservoir serves three purposes I can identify: It supplies a
reserve of hydraulic fluid to replace small amounts lost in normal
operation, it allows for expansion and contraction of the system
volume, and it allows the system to be pumped up to compensate for a
bubble in the line without remaining pumped up after the lever is
released.
Chalo
Chalo
wrote:
> Ben C <spams...@spam.eggs> considered Tue, 27 Jan 2009 02:39:13 -0600
> the perfect time to write:
>
>
>
> >[...]
> >>>> The link describes what we've been calling an "open" system. I'm less
> >>>> clear on the layout of a "closed" system-- is it just the same as an
> >>>> open system, with a little bit of air at the top, but just with the
> >>>> reservoir cap glued on; or is there absolutely no air in there at all?
>
> >>> In a closed system, there is no air at all, and no "reservoir".
> >>> Since the system is closed, why would you need a reservoir?
>
> >> er, to allow for an equalization port and thermal expansion - you know,
> >> so your brakes don't lock on when they get hot?
>
> >So there must be some air at the top? Or a plunger that moves up and
> >down, or something to allow the whole system's total volume to change?
>
> rim. The clearance is easily enough to accomodate this.
Chalo
>
> If the volume changes, the pad just moves towards or away from the
> rim. The clearance is easily enough to accomodate this.
Not all disc brakes have pads that retract positively. Some simply
allow the small excursions of the rotor to push the pads ever so
slightly back from the braking surface.
Chalo
Clive George
news:4856a6ca-d78e-4959...@p36g2000prp.googlegroups.com...
Yeah - but we're talking about rim brakes :-)
(magura rim brakes have really quite a lot of rim clearance - unlike cables,
the lever pretty much stops moving when you hit the bite point, so this
works).
Chalo
>
> (magura rim brakes have really quite a lot of rim clearance - unlike cables,
> the lever pretty much stops moving when you hit the bite point, so this
> works).
I used them around 1990. I liked the sharp feel and excellent maximum
braking power, but I found the rock-like pads available at that time
pretty uninspiring and noisy. At some point I bled them with
drugstore mineral oil, and their lever return became sluggish.
I didn't know what brake boosters were for then (though I was aware of
Gorilla boosters), and my brakes didn't come with them, so the Maguras
were pretty brutal to my brake bosses.
Chalo
Clive George
news:hkpun4tajj63t28m7...@4ax.com...
>>ok andre, i can't be bothered to spend ages digging through every single
>>product detail of any particular manufacturer's website. mea culpa.
>>but if you think that means, contrary to basic physics, that "closed"
>>systems /aren't/ subject to binding when the brake fluid heats and
>>expands, you'd be /way/ off base.
>>
> Yet they work, and work well.
> Maybe it's just that nobody else is stupid enough to adjust the pads
> to within a gnats tadger of the rim.
Heh - something I discovered on installation. My fingers aren't as strong
when they're at the start of the lever stroke, so I arrange it so there's
enough of a gap to get them to a better part of the stroke.
Chalo
>
> Andre Jute wrote:
> >
> > You'd be less of a tiresome internet contrarian, Jimbo, if you
> > occasionally did your homework before spouting off.
>
> product detail of any particular manufacturer's website. mea culpa.
What?! Aren't you the "ferret out the secret tension limits of every
manufacturer's rim or suffer my wrath and contempt" guy?
Ahem, there are specs for these things, you know! Harrumph!
Chalo