Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta HydraulicDisc?

[Ben C]

On 2007-09-06, Dave Larrington <[email protected]> wrote:
> In news:[email protected],
> Ben C <[email protected]> tweaked the Babbage-Engine to tell us:
>
>> Yes, although I also got that "perhaps 170C" from a bit of googling.
>> The page I found made a distinction between "wet" and "dry" boiling
>> points, "wet" being what you get when your brake fluid has absorbed
>> 3% of water.
>>
>> Here it is: http://www.afcoracing.com/tech_pages/fluid.shtml
>>
>> I went for the "wet" boiling point of DOT 4 since I heard somewhere
>> else that bicycle brake fluid boils much more easily than the car
>> stuff (although it strips the paint less).
>>
>> Brake fluid should never boil in a car unless it's very old. You
>> should be able to get the pads practically on fire before the fluid
>> boils. But I have heard tell of fluid boiling occurring with MTB
>> disks, implying to me that the stuff people are putting in boils at a
>> rather lower temp than DOT4 or DOT5.1.
>>
>> Dry for DOT5.1 is 288 deg C according to them.
>
>
> I use DOT 5.1 from Halfrauds in all my hydraulic discs and can't recall any
> problems which might have been caused by boiling fluid. This is 99.9%
> on-road, admittedly, but even try to keep a recumbent down to a sane speed
> on a steep wet twisty downhill in the middle of the night using only the
> rear brake[1] it's been OK.

Yes I think you'd have a hard time boiling DOT 5.1 in anything, which is
as it should be. Boiling brake fluid is not something you file under
"acceptable".

> 1 - the front one decided to lose interest after a minor off - no sign of a
> fluid leak and rebleeding seems to have restored normal functionality.
> Colour me baffled.

Perhaps it got a gulp of air into the lines when it was upside down.

 

[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>You will find those are not intended for anything like loaded touring
>>or additionally have a drum or disc [1] brake intended for use as a
>>drag brake. For example, a racing tandem doesn't have these issues.
>maybe so but seems plenty about. which seems a odd saving when the
>tamdem can be the price of a new car.

It's also a large weight saving. The Arai brake, which is the only really
effective solution for long descents, weighs a ton because it's a giant
heatsink.

>i can see that Santana have spent a lot of time and effort into tamdem
>brakes. consdering the possible weight, that still looks quite under
>powered when you consider the weights.

But your perceptions of brake "power" are worthless because every decent
design of brake has exactly the same stopping power on a solo.

>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
>>easier to lift the rear wheel.
>if you don't shift your weight about yes,

What I say remains accurate. It's elementary mechanics.
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[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>If you're just "yanking on the lever" with a well-adjusted cable rim
>>brake, that's your poor technique.
>no it is easyer to make a controlled emergency stop if the lever
>requires less force.

This is not necessarily true. If the brake could be put completely on with
the touch of a feather, it would be impossible to make a controlled
emergency stop; if the brake required your absolute maximum hand strength
to put on, it would also be impossible. Therefore it is nonsense to say
that less (or more) force always makes it easier.

Somewhere between those two points is a spot or region where it is
easiest, but to say that that's a spot not a region and that that spot
happens to be the amount of force required by the brakes you have _and_
that that will be true for any user is pure guesswork.

>>>2nd at higher speeds you will have a job to lock the wheel, unless you
>>>delbertly unweight a wheel etc.
>>This one won't wash with anyone who has made emergency stops downhill on
>>road. We might not brake as much, but the speeds are higher.
>if your locking managing to lock the wheels at high speeds in the dry
>etc then you either have tires with not enought grip or are not
>countering with your weight. which a hill would help with.

Did I say I'd locked the wheels? No.

But - more than once - descending at speed, with heavy panniers (so with
the overall centre of gravity already lower and to the rear) - I've
had to brake so hard it's finished with the thump of the rear wheel
regaining contact with the road.

Bog ordinary cantilevers. You don't need hydraulic discs to make a
controller emergency stop at high speeds.
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[David Damerell]

Quoting Peter Clinch <[email protected]>:
>David Damerell wrote:
>>Well, no. There's a dodge going on here where the real advantage of not
>>needing as much maintenance is twisted into better performance (because
>>the performance is better when unmaintained). That's double accounting; if
>>you're going to argue based on the unmaintained performance, you can't
>>argue that they need less maintenance.
>Two things:
>1) maintenance is an improved feature
>2) performance, via better control through more sensitivity, is an
>improved feature.

But that's a dodge. What you were talking about was performance via not
degrading as badly when unmaintained, and that's double accounting with
"less maintenance".

Performance via better control through more sensitivity is something
that's basically been made up here. It's the usual confusion - "this
_feels_ better so it must _be_ better" (combined with "this feels better
_to me_ so it must be better _for everyone_").

As I've just written in another article - too much sensitivity won't work,
too much force won't work. Somewhere between there's a sweet spot or
region; when you say you know that's a spot and it happens to be where
your brake setup is - for every user, no less - you're just speculating.
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[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>If you're just "yanking on the lever" with a well-adjusted cable rim
> >>brake, that's your poor technique.
> >no it is easyer to make a controlled emergency stop if the lever
> >requires less force.
>
> This is not necessarily true. If the brake could be put completely on with
> the touch of a feather, it would be impossible to make a controlled
> emergency stop; if the brake required your absolute maximum hand strength
> to put on, it would also be impossible. Therefore it is nonsense to say
> that less (or more) force always makes it easier.
>
> Somewhere between those two points is a spot or region where it is
> easiest, but to say that that's a spot not a region and that that spot
> happens to be the amount of force required by the brakes you have _and_
> that that will be true for any user is pure guesswork.
>
yes still needs to be some resistance, or it would be too easy to be a
system that was on/off

> >>>2nd at higher speeds you will have a job to lock the wheel, unless you
> >>>delbertly unweight a wheel etc.
> >>This one won't wash with anyone who has made emergency stops downhill on
> >>road. We might not brake as much, but the speeds are higher.
> >if your locking managing to lock the wheels at high speeds in the dry
> >etc then you either have tires with not enought grip or are not
> >countering with your weight. which a hill would help with.
>
> Did I say I'd locked the wheels? No.

look back at your post not the snippage here, you pritty much did if not
in actualality.
>
> But - more than once - descending at speed, with heavy panniers (so with
> the overall centre of gravity already lower and to the rear) - I've
> had to brake so hard it's finished with the thump of the rear wheel
> regaining contact with the road.

yes, but it's very unlikely the paniers are close to your weight, you
can make a much more impact moving your body, assuming the bike allows
it, that is.
>
> Bog ordinary cantilevers. You don't need hydraulic discs to make a
> controller emergency stop at high speeds.

no you don't but all things being equal they should make a better job of
it. it's a over used line but power is nothing with out control.

look do you really think that it's a big con and that brakes haven't
improved over the years? motor vehicals have been useing disks and
hydraulic at that for years, that some companies put some that where
simply not up for the job says more about those companies than what
hydraulic disks can and can't do.

roger
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[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>You will find those are not intended for anything like loaded touring
> >>or additionally have a drum or disc [1] brake intended for use as a
> >>drag brake. For example, a racing tandem doesn't have these issues.
> >maybe so but seems plenty about. which seems a odd saving when the
> >tamdem can be the price of a new car.
>
> It's also a large weight saving. The Arai brake, which is the only really
> effective solution for long descents, weighs a ton because it's a giant
> heatsink.
>
consdering that the weight of a tamdem can be fairly impressive ie in
the folks, thus two big men + gear and thats a whole lot of trouble.

> >i can see that Santana have spent a lot of time and effort into tamdem
> >brakes. consdering the possible weight, that still looks quite under
> >powered when you consider the weights.
>
> But your perceptions of brake "power" are worthless because every decent
> design of brake has exactly the same stopping power on a solo.
>
maybe in paper, but taking my old cant bike away from the rolling downs
and to the beacons shows that while it's brakes can cope with the soft
lumps of the south east. proper hills it lacks the power, compared with
a newer bike with disks.


> >>Wrong again. Regardless of shifting weight, a downhill gradient makes it
> >>easier to lift the rear wheel.
> >if you don't shift your weight about yes,
>
> What I say remains accurate. It's elementary mechanics.

within a very tight artifial peramitors yes. if you shift your postion
and weight the rear is quite useable. even down very steep gradient's

roger
--
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[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>But your perceptions of brake "power" are worthless because every decent
>>design of brake has exactly the same stopping power on a solo.
>maybe in paper,

And in elementary mechanics.

>but taking my old cant bike away from the rolling downs
>and to the beacons shows that while it's brakes can cope with the soft
>lumps of the south east. proper hills it lacks the power, compared with
>a newer bike with disks.

Which is still rubbish because an increasing downhill gradient _reduces_
the maximum deceleration.

>>>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
>>>>easier to lift the rear wheel.
>>>if you don't shift your weight about yes,
>>What I say remains accurate. It's elementary mechanics.
>within a very tight artifial peramitors yes. if you shift your postion
>and weight the rear is quite useable. even down very steep gradient's

Which is also still rubbish as anyone can determine with heavy panniers.
30kg in panniers shifts the centre of gravity more than you can by moving
your bottom; and with 30kg in panniers you can still lift the rear wheel
under braking; and a downhill gradient still reduces the maximum
deceleration before that happens.

You're just clinging to purely psychosomatic ideas of brake power. It
won't wash; and particularly it won't wash with anyone familiar with
tandem applications, where you actually _can_ produce differences in brake
power.
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[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>Somewhere between those two points is a spot or region where it is
>>easiest, but to say that that's a spot not a region and that that spot
>>happens to be the amount of force required by the brakes you have _and_
>>that that will be true for any user is pure guesswork.
>yes still needs to be some resistance, or it would be too easy to be a
>system that was on/off

Reducing your guesswork to what it is.

>>>if your locking managing to lock the wheels at high speeds in the dry
>>>etc then you either have tires with not enought grip or are not
>>>countering with your weight. which a hill would help with.
>>id I say I'd locked the wheels? No.
>look back at your post not the snippage here, you pritty much did if not
>in actualality.

Let's see a quote from you that shows it, then. Hint; you can't.

>>But - more than once - descending at speed, with heavy panniers (so with
>>the overall centre of gravity already lower and to the rear) - I've
>>had to brake so hard it's finished with the thump of the rear wheel
>>regaining contact with the road.
>yes, but it's very unlikely the paniers are close to your weight, you
>can make a much more impact moving your body,

That's also not true. The panniers don't weigh what a body does, true -
but you can easily have 20 or 30kg there - and they are also much further
from the centre of gravity of a normal bike/rider system than a moved
bottom is, so they affect the CoG proportionately more. It's definitely in
the same ballpark.

>>Bog ordinary cantilevers. You don't need hydraulic discs to make a
>>controller emergency stop at high speeds.
>no you don't but all things being equal they should make a better job of
>it.

You can't make a better job of stopping than stopping with the rear wheel
on the edge of lifting.

>look do you really think that it's a big con and that brakes haven't
>improved over the years?

I certainly think it's partly marketing, but I think the advantages of
discs aren't what you think they are. "Power" is a red herring on solos,
and tandems have not found discs exceptionally powerful.

We've had real advantages of hydraulic disc systems listed. Immunity to
wet muddy conditions; low maintenance (especially no rim wear). And, of
course, if a rider has very weak hands they will get a real benefit from
the reduced application force. But "power"? Not a chance.

>motor vehicals have been useing disks and hydraulic at that for years,

So what? Are you going to put a five-speed gearbox on your bike next?
Just because it fits motorised applications doesn't mean it fits bikes.
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[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>But your perceptions of brake "power" are worthless because every decent
> >>design of brake has exactly the same stopping power on a solo.
> >maybe in paper,
>
> And in elementary mechanics.

i'm sure it terms of heat they are much of a muchness. and yes if you
don't move at point X the bike will endo.
>
> >but taking my old cant bike away from the rolling downs
> >and to the beacons shows that while it's brakes can cope with the soft
> >lumps of the south east. proper hills it lacks the power, compared with
> >a newer bike with disks.
>
> Which is still rubbish because an increasing downhill gradient _reduces_
> the maximum deceleration.
>
yes if i sit on the saddle and just jank the brake, but most will learn
to get out of the saddle and use that weight.

> >>>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
> >>>>easier to lift the rear wheel.
> >>>if you don't shift your weight about yes,
> >>What I say remains accurate. It's elementary mechanics.
> >within a very tight artifial peramitors yes. if you shift your postion
> >and weight the rear is quite useable. even down very steep gradient's
>
> Which is also still rubbish as anyone can determine with heavy panniers.
> 30kg in panniers shifts the centre of gravity more than you can by moving
> your bottom; and with 30kg in panniers you can still lift the rear wheel
> under braking; and a downhill gradient still reduces the maximum
> deceleration before that happens.

yes of coarse a hill will increase a heavly laden bikes endo point, but
you weigh a lot more than 30KG and on some bikes you can move that
weight around a lot, not just a minor shift, that is one reason Mountain
bikes don't allways have the sadle up high so that weight can be
shifted. you can get suprisingly low and far back, the limit is the
sadle and the rear tire.
>
> You're just clinging to purely psychosomatic ideas of brake power. It
> won't wash; and particularly it won't wash with anyone familiar with
> tandem applications, where you actually _can_ produce differences in brake
> power.

try taking a bike up and down steep hills good 30% shift your weight
around by that i don't mean your bottom as you put it, but bodly get
right back as far as you can go and as far forward. you may be suprised.

roger
--
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[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>Somewhere between those two points is a spot or region where it is
> >>easiest, but to say that that's a spot not a region and that that spot
> >>happens to be the amount of force required by the brakes you have _and_
> >>that that will be true for any user is pure guesswork.
> >yes still needs to be some resistance, or it would be too easy to be a
> >system that was on/off
>
> Reducing your guesswork to what it is.

brakes that can be feathered with out having to use any force proper
will be easyer to control, most things requiring fine control try not to
require too much effort.
>
> >>>if your locking managing to lock the wheels at high speeds in the dry
> >>>etc then you either have tires with not enought grip or are not
> >>>countering with your weight. which a hill would help with.
> >>id I say I'd locked the wheels? No.
> >look back at your post not the snippage here, you pritty much did if not
> >in actualality.
>
> Let's see a quote from you that shows it, then. Hint; you can't.

fine

">2nd at higher speeds you will have a job to lock the wheel, unless you
delbertly unweight a wheel etc."

>This one won't wash with anyone who has made emergency stops downhill
>on
>road. We might not brake as much, but the speeds are higher.
>
if your not saying you lock your wheels at speed then what are you
saying?

> >>But - more than once - descending at speed, with heavy panniers (so with
> >>the overall centre of gravity already lower and to the rear) - I've
> >>had to brake so hard it's finished with the thump of the rear wheel
> >>regaining contact with the road.
> >yes, but it's very unlikely the paniers are close to your weight, you
> >can make a much more impact moving your body,
>
> That's also not true. The panniers don't weigh what a body does, true -
> but you can easily have 20 or 30kg there - and they are also much further
> from the centre of gravity of a normal bike/rider system than a moved
> bottom is, so they affect the CoG proportionately more. It's definitely in
> the same ballpark.

the only limit to how far back and low is rear tire, and saddle more
than enought to be more than 30KG of panniers. particulally as with 30KG
of panniers the possiblt of shifting ones weight much is limited.
>
> >>Bog ordinary cantilevers. You don't need hydraulic discs to make a
> >>controller emergency stop at high speeds.
> >no you don't but all things being equal they should make a better job of
> >it.
>
> You can't make a better job of stopping than stopping with the rear wheel
> on the edge of lifting.
>
correct which is why you need to shift ones' weight back and push that
point to a higher point.

not needed on a tamdem but is on a solo.

> >look do you really think that it's a big con and that brakes haven't
> >improved over the years?
>
> I certainly think it's partly marketing, but I think the advantages of
> discs aren't what you think they are. "Power" is a red herring on solos,
> and tandems have not found discs exceptionally powerful.
>
considering the weight that a tamdem could be, they really should be
useing something a with a lot more bite. even the big disks you like are
still rather light weight.

power isn't a red herring, while it is possible to endo it is also
possible to counter, up to a point, which disks are not at so far.

> We've had real advantages of hydraulic disc systems listed. Immunity to
> wet muddy conditions; low maintenance (especially no rim wear). And, of
> course, if a rider has very weak hands they will get a real benefit from
> the reduced application force. But "power"? Not a chance.

reduced application force is certinaly a real plus in some situations,
very few roads are steep enought to be a issue though tamdems might make
more. but certinaly off road, the differnace from decending down a long
steep hill on cant's or disks can be felt.

and also mean that one doesn't need to put whole hand on lever when you
really should be worring about that rock...
>
> >motor vehicals have been useing disks and hydraulic at that for years,
>
> So what? Are you going to put a five-speed gearbox on your bike next?
> Just because it fits motorised applications doesn't mean it fits bikes.

it means just becuase x number of companies made a balls up of it
doesn't mean there is anything wrong with the underlying idea.

it works else where and very well. on faster heaver vehicals than a
tamdem.

roger
--
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[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>Quoting Roger Merriman <[email protected]>:
>>>David Damerell <[email protected]> wrote:
>>>>But your perceptions of brake "power" are worthless because every decent
>>>>design of brake has exactly the same stopping power on a solo.
>>>maybe in paper,
>>And in elementary mechanics.
>i'm sure it terms of heat they are much of a muchness. and yes if you
>don't move at point X the bike will endo.

And for a given bottom position, every design of brake has the same
stopping power.

>>>but taking my old cant bike away from the rolling downs
>>>and to the beacons shows that while it's brakes can cope with the soft
>>>lumps of the south east. proper hills it lacks the power, compared with
>>>a newer bike with disks.
>>Which is still rubbish because an increasing downhill gradient _reduces_
>>the maximum deceleration.
>yes if i sit on the saddle and just jank the brake, but most will learn
>to get out of the saddle and use that weight.

Doesn't matter. If you can brake on the those soft lumps, you can manage
the deceleration possible on proper hills because it _is less_.

>>Which is also still rubbish as anyone can determine with heavy panniers.
>>30kg in panniers shifts the centre of gravity more than you can by moving
>>your bottom; and with 30kg in panniers you can still lift the rear wheel
>>under braking; and a downhill gradient still reduces the maximum
>>deceleration before that happens.
>yes of coarse a hill will increase a heavly laden bikes endo point, but
>you weigh a lot more than 30KG and on some bikes you can move that
>weight around a lot,

You can move _some_ of that weight around a lot; your arms and legs don't
move so much for a given bottom shift. And when we say "a lot", it's not a
lot compared to the distance that rear panniers are below and to the rear
of the saddle.

>>You're just clinging to purely psychosomatic ideas of brake power. It
>>won't wash; and particularly it won't wash with anyone familiar with
>>tandem applications, where you actually _can_ produce differences in brake
>>power.
>try taking a bike up and down steep hills good 30%

When the gradient gets steep enough, the available braking before endo is
small regardless of bottom position. That's one reason it's so blindingly
obvious you're taking rubbish; you're picking the worse case for a brake
to demonstrate supposedly superior power.

>shift your weight around by that i don't mean your bottom as you put it

Yes, you do. Your hands won't move; your shoulders won't get any further
from the handlebars than they are with straight arms, although they will
drop a bit. Your feet aren't going anywhere. The bottom is exactly the
part that moves a lot.
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[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>Quoting Roger Merriman <[email protected]>:
>>>yes still needs to be some resistance, or it would be too easy to be a
>>>system that was on/off
>>Reducing your guesswork to what it is.
>brakes that can be feathered with out having to use any force proper
>will be easyer to control, most things requiring fine control try not to
>require too much effort.

This is just restating the guesswork. Yes, there's a sweet spot or region
- but you've failed to show that the brakes you personally prefer are in
it or that other designs are outside it - for all possible rider hand
strengths.

>>>look back at your post not the snippage here, you pritty much did if not
>>>in actualality.
>>Let's see a quote from you that shows it, then. Hint; you can't.
>fine

Coo, you're literally minded. But let's see a quote from _me_ that shows I
said it?

>>This one won't wash with anyone who has made emergency stops downhill
>>on road. We might not brake as much, but the speeds are higher.
>if your not saying you lock your wheels at speed then what are you
>saying?

On a good surface what happens first with the front brake - front lock or
rear lift?

>the only limit to how far back and low is rear tire, and saddle more
>than enought to be more than 30KG of panniers.

No. Atop the rear tyre, the very bottom of the weight you shifted is at
the top of where panniers would be.

>particulally as with 30KG
>of panniers the possiblt of shifting ones weight much is limited.

Try reading comprehension; it's either/or. The point is, a rider with
heavy panniers has an overall centre of gravity just as low and rearward
without shifting his weight.

>>You can't make a better job of stopping than stopping with the rear wheel
>>on the edge of lifting.
>correct which is why you need to shift ones' weight back and push that
>point to a higher point.

Try reading comprehension.

>>I certainly think it's partly marketing, but I think the advantages of
>>discs aren't what you think they are. "Power" is a red herring on solos,
>>and tandems have not found discs exceptionally powerful.
>considering the weight that a tamdem could be, they really should be
>useing something a with a lot more bite.

That's sort of the point. There's actually some chance of discovering
which brakes are powerful.

>>We've had real advantages of hydraulic disc systems listed. Immunity to
>>wet muddy conditions; low maintenance (especially no rim wear). And, of
>>course, if a rider has very weak hands they will get a real benefit from
>>the reduced application force. But "power"? Not a chance.
>reduced application force is certinaly a real plus in some situations,
>very few roads are steep enought to be a issue

As I've explained to you several times now, the steeper the road, the
_less_ the maximum braking.

>and also mean that one doesn't need to put whole hand on lever when you
>really should be worring about that rock...

Yes, I worry about rocks with my fingers. Not.

>>So what? Are you going to put a five-speed gearbox on your bike next?
>>Just because it fits motorised applications doesn't mean it fits bikes.
>it works else where and very well. on faster heaver vehicals than a
>tamdem.

I've no doubt a disc system as heavy-duty as those on a motor car would
make a fine brake, if you didn't mind it weighing as much as your bike
did before you fitted it. Of course, it would still be pointless on a solo
because the limit on a solo still isn't braking "power".
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruitkonomiyaki,pickup_types:"!$?=/,scores:
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rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace

 

[Peter Clinch]

David Damerell wrote:

> This is not necessarily true. If the brake could be put completely on with
> the touch of a feather, it would be impossible to make a controlled
> emergency stop; if the brake required your absolute maximum hand strength
> to put on, it would also be impossible. Therefore it is nonsense to say
> that less (or more) force always makes it easier.
>
> Somewhere between those two points is a spot or region where it is
> easiest, but to say that that's a spot not a region and that that spot
> happens to be the amount of force required by the brakes you have _and_
> that that will be true for any user is pure guesswork.

But rather less guesswork if they happen to have considerable experience
of multiple brake systems. How much time have you actually spent using
hydraulic brake systems?

> Bog ordinary cantilevers. You don't need hydraulic discs to make a
> controller emergency stop at high speeds.

No, but that doesn't mean to say it wouldn't be easier. Again I ask,
how much time have you actually spent using hydraulic brake systems?

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Peter Clinch]

David Damerell wrote:

> But that's a dodge. What you were talking about was performance via not
> degrading as badly when unmaintained, and that's double accounting with
> "less maintenance".

Oh deary me, I have talked about *both* performance being better through
better feel when maintained and being better in all respects when not
maintained and left for some time.

That's two things. Both are better with hydraulics.

> Performance via better control through more sensitivity is something
> that's basically been made up here.

No, it's based on direct experience. How much experience do you
actually have of hydraulic brakes? How much experience do world cup
MTBers have of hydraulic brakes? And which actuation method do they prefer?

> It's the usual confusion - "this
> _feels_ better so it must _be_ better" (combined with "this feels better
> _to me_ so it must be better _for everyone_").

As opposed to "this is what I use and I think it's fine so obviously
anyone else finding anuthing better is deluded"...

> As I've just written in another article - too much sensitivity won't work,

It isn't "too much" that hydraulics give you, it's more than cables, but
less than too much. A better amount, in other words.

> too much force won't work. Somewhere between there's a sweet spot or
> region; when you say you know that's a spot and it happens to be where
> your brake setup is - for every user, no less - you're just speculating.

For every user, no, but if one is playing the advice/probability game
then you go with a best liklihood, and it's most likely that A Given
User will find hydraulics better in use than cables to start with, and
quite a bit better than that with time as the cables fail to degrade
IMHO. How much experience of hydraulic brakes do you actually have?

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>Quoting Roger Merriman <[email protected]>:
> >>>David Damerell <[email protected]> wrote:
> >>>>But your perceptions of brake "power" are worthless because every decent
> >>>>design of brake has exactly the same stopping power on a solo.
> >>>maybe in paper,
> >>And in elementary mechanics.
> >i'm sure it terms of heat they are much of a muchness. and yes if you
> >don't move at point X the bike will endo.
>
> And for a given bottom position, every design of brake has the same
> stopping power.

yes but you'll have a job realising that. you will not beable to pull
the levers hard enought.

you can get to the point that the bike will not endo how ever hard you
pull the brakes.
>
> >>>but taking my old cant bike away from the rolling downs
> >>>and to the beacons shows that while it's brakes can cope with the soft
> >>>lumps of the south east. proper hills it lacks the power, compared with
> >>>a newer bike with disks.
> >>Which is still rubbish because an increasing downhill gradient _reduces_
> >>the maximum deceleration.
> >yes if i sit on the saddle and just jank the brake, but most will learn
> >to get out of the saddle and use that weight.
>
> Doesn't matter. If you can brake on the those soft lumps, you can manage
> the deceleration possible on proper hills because it _is less_.
>
no it's perfectly possible to counter. it isn't hard at all.

> >>Which is also still rubbish as anyone can determine with heavy panniers.
> >>30kg in panniers shifts the centre of gravity more than you can by moving
> >>your bottom; and with 30kg in panniers you can still lift the rear wheel
> >>under braking; and a downhill gradient still reduces the maximum
> >>deceleration before that happens.
> >yes of coarse a hill will increase a heavly laden bikes endo point, but
> >you weigh a lot more than 30KG and on some bikes you can move that
> >weight around a lot,
>
> You can move _some_ of that weight around a lot; your arms and legs don't
> move so much for a given bottom shift. And when we say "a lot", it's not a
> lot compared to the distance that rear panniers are below and to the rear
> of the saddle.
>
on a bike with out rider yes, but a heavily panniered bike will have a
rider when moving, and is likely to be a lot heaver, higher and more
forward, reduceing the benfit of the paniers. with regard to endos

> >>You're just clinging to purely psychosomatic ideas of brake power. It
> >>won't wash; and particularly it won't wash with anyone familiar with
> >>tandem applications, where you actually _can_ produce differences in brake
> >>power.
> >try taking a bike up and down steep hills good 30%
>
> When the gradient gets steep enough, the available braking before endo is
> small regardless of bottom position. That's one reason it's so blindingly
> obvious you're taking rubbish; you're picking the worse case for a brake
> to demonstrate supposedly superior power.

i'm not i'm pointing out that it is possible to counter the endo and
that riding up and down steep hills doesn't not mean that you end up
endoing every time you have to do a emergecy brake.
>
> >shift your weight around by that i don't mean your bottom as you put it
>
> Yes, you do. Your hands won't move; your shoulders won't get any further
> from the handlebars than they are with straight arms, although they will
> drop a bit. Your feet aren't going anywhere. The bottom is exactly the
> part that moves a lot.

on a mountain bike your shoulder will be above and just behind the
handle bars, you can move your shoulder to just above the saddle very
few hills if any would need such a move. your hands and feet stay put
but you can mover your trunk in a ark down and behind. which puts a lot
of weight lower down and rear.

roger
--
www.rogermerriman.com

 

[Roger Merriman]

David Damerell <[email protected]> wrote:

> Quoting Roger Merriman <[email protected]>:
> >David Damerell <[email protected]> wrote:
> >>Quoting Roger Merriman <[email protected]>:
> >>>yes still needs to be some resistance, or it would be too easy to be a
> >>>system that was on/off
> >>Reducing your guesswork to what it is.
> >brakes that can be feathered with out having to use any force proper
> >will be easyer to control, most things requiring fine control try not to
> >require too much effort.
>
> This is just restating the guesswork. Yes, there's a sweet spot or region
> - but you've failed to show that the brakes you personally prefer are in
> it or that other designs are outside it - for all possible rider hand
> strengths.
>
i don't care if the brakes are disks rims, gas, wire fluid, or what
ever.

what i do care about are brakes that will scrub off speed ie 40 to 50
range and allow one to decend with power left.

> >>>look back at your post not the snippage here, you pritty much did if not
> >>>in actualality.
> >>Let's see a quote from you that shows it, then. Hint; you can't.
> >fine
>
> Coo, you're literally minded. But let's see a quote from _me_ that shows I
> said it?
>
> >>This one won't wash with anyone who has made emergency stops downhill
> >>on road. We might not brake as much, but the speeds are higher.
> >if your not saying you lock your wheels at speed then what are you
> >saying?
>
> On a good surface what happens first with the front brake - front lock or
> rear lift?
>
rear lift normally, hence the need to counter.

> >the only limit to how far back and low is rear tire, and saddle more
> >than enought to be more than 30KG of panniers.
>
> No. Atop the rear tyre, the very bottom of the weight you shifted is at
> the top of where panniers would be.
>
no you get a lot further behind than that. at the end of the ark you
will either hit the very edge of the tire.

> >particulally as with 30KG
> >of panniers the possiblt of shifting ones weight much is limited.
>
> Try reading comprehension; it's either/or. The point is, a rider with
> heavy panniers has an overall centre of gravity just as low and rearward
> without shifting his weight.

with paniers you still have yours truely which is much heaver, far
higher, and forward. which more than makes up for the panniers.

>
> >>You can't make a better job of stopping than stopping with the rear wheel
> >>on the edge of lifting.
> >correct which is why you need to shift ones' weight back and push that
> >point to a higher point.
>
> Try reading comprehension.
>
> >>I certainly think it's partly marketing, but I think the advantages of
> >>discs aren't what you think they are. "Power" is a red herring on solos,
> >>and tandems have not found discs exceptionally powerful.
> >considering the weight that a tamdem could be, they really should be
> >useing something a with a lot more bite.
>
> That's sort of the point. There's actually some chance of discovering
> which brakes are powerful.
>
there is differnce between heat and power.
> >>We've had real advantages of hydraulic disc systems listed. Immunity to
> >>wet muddy conditions; low maintenance (especially no rim wear). And, of
> >>course, if a rider has very weak hands they will get a real benefit from
> >>the reduced application force. But "power"? Not a chance.
> >reduced application force is certinaly a real plus in some situations,
> >very few roads are steep enought to be a issue
>
> As I've explained to you several times now, the steeper the road, the
> _less_ the maximum braking.

yes and as i've pointed out you can very effectvly counter that.
>
> >and also mean that one doesn't need to put whole hand on lever when you
> >really should be worring about that rock...
>
> Yes, I worry about rocks with my fingers. Not.

if your trying to navigate a technical section you will want to keep
most of your fingers on the bars for control not brakes.
>
> >>So what? Are you going to put a five-speed gearbox on your bike next?
> >>Just because it fits motorised applications doesn't mean it fits bikes.
> >it works else where and very well. on faster heaver vehicals than a
> >tamdem.
>
> I've no doubt a disc system as heavy-duty as those on a motor car would
> make a fine brake, if you didn't mind it weighing as much as your bike
> did before you fitted it. Of course, it would still be pointless on a solo
> because the limit on a solo still isn't braking "power".

it wouldn't need to be as heavy weight, but bike brakes are light weight
things, look at the disks very thin, there is a middle ground.

roger
--
www.rogermerriman.com

 

[Jon]

"Roger Merriman" <[email protected]> wrote
>
> what i do care about are brakes that will scrub off speed ie 40 to 50
> range and allow one to decend with power left.

Not sure what "decend with power left" means.

But it seems to me that there are perhaps some points of agreement:

1) for braking methods that rely on slowing wheel rotations [1],
there is a maximum obtainable deceleration rate on a bicycle
before the rear will lift and rotate around the front contact
point.

2) changing weight distribution (or bicycle geometry) affects that
maximum deceleration rate.

3) going down a hill implicitly shifts the bike and rider weight
distribution forward.

4) the weight distribution downhill cannot be "further back" than
it would be with the same rider position on flat ground, hence
the maximum possible deceleration rate downhill is lower
than on flat.

5) properly designed and adjusted disk and rim bicycle braking
systems, cable and hydraulic, can produce braking force greater
than the maximum possible deceleration rate.

6) braking power above that required to produce the maximum
deceleration rate is irrelevant for how quickly one may stop.

7) [gratuitous ARBC content] long wheelbase recumbent
bikes certainly have a greater maximum potential
deceleration rate than upright bikes.

This says nothing about which system is nicer, easier to use,
maintain, modulate and control, or resists fading, or is better
suited for wet and muddy conditions, etc... Or which one
makes your bike look cool and your friends jealous! %^)

There was recently a very good explanation of the limits
of bicycle braking on the phred touring mailing list. Should
be in the archives at:

http://www.phred.org/mailman/listinfo/touring

It was pointed why it's not a good idea to follow cars at
high speeds too closely on a bicycle. Cars can stop at
much higher deceleration rates than bicycles.

Jon Meinecke

[1] alternative braking methods could include dropping an anchor,
deploying a drag parachute, firing retro-rockets, hitting a large
rock face (with or without a tunnel entrance painted on it), etc...

See Wiley Coyote field tests of Acme Products for examples...
%^)

 

[Jon]

"Jon" <[email protected]> wrote
> There was recently a very good explanation of the limits
> of bicycle braking on the phred touring mailing list. Should
> be in the archives at:
>

Here's the link to the archived article on bike braking limits
from the touring mailing list

http://search.bikelist.org/getmsg.asp?Filename=touring.10709.0118.eml

Jon

 

[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>Quoting Roger Merriman <[email protected]>:
>>And for a given bottom position, every design of brake has the same
>>stopping power.
>yes but you'll have a job realising that. you will not beable to pull
>the levers hard enought.

Also rubbish, and a particularly worthless piece of rubbish to produce to
me when you know I ride tandem. Our centre of gravity's far further back
than you can produce with any contortions in the saddle; I can brake
harder than any solo. Hand strength is not the limiting factor.

>on a bike with out rider yes, but a heavily panniered bike will have a
>rider when moving, and is likely to be a lot heaver, higher and more
>forward, reduceing the benfit of the paniers. with regard to endos

Reading comprehension again. The point is, the CoG of "normal rider
position, heavy panniers" is as far back and down as "abnormal rider
position".

>>When the gradient gets steep enough, the available braking before endo is
>>small regardless of bottom position. That's one reason it's so blindingly
>>obvious you're taking rubbish; you're picking the worse case for a brake
>>to demonstrate supposedly superior power.
>i'm not

Yes, you are; the steeper the hill, the less the braking before an endo.
--
David Damerell <[email protected]> Kill the tomato!
Today is Leicesterday, August.

 

[David Damerell]

Quoting Roger Merriman <[email protected]>:
>David Damerell <[email protected]> wrote:
>>>if your not saying you lock your wheels at speed then what are you
>>>saying?
>>On a good surface what happens first with the front brake - front lock or
>>rear lift?
>rear lift normally, hence the need to counter.

So I was not saying you lock the wheels. You _made that up_.

>>Try reading comprehension; it's either/or. The point is, a rider with
>>heavy panniers has an overall centre of gravity just as low and rearward
>>without shifting his weight.
>with paniers you still have yours truely which is much heaver, far
>higher, and forward. which more than makes up for the panniers.

Well, no. Panniers weigh less; they're further from the normal centre of
gravity. Works out about the same.

>>>considering the weight that a tamdem could be, they really should be
>>>useing something a with a lot more bite.
>>That's sort of the point. There's actually some chance of discovering
>>which brakes are powerful.
>there is differnce between heat and power.

Yes, and I'm talking about power. Tandems decelerate twice the load and
can decelerate harder.

>>As I've explained to you several times now, the steeper the road, the
>>_less_ the maximum braking.
>yes and as i've pointed out you can very effectvly counter that.

Well, no, you've babbled aimlessly. A given bottom position can also be
used on a shallower slope; once you do that, on the steeper slope, the
maximum braking is... less.

>>I've no doubt a disc system as heavy-duty as those on a motor car would
>>make a fine brake, if you didn't mind it weighing as much as your bike
>>did before you fitted it. Of course, it would still be pointless on a solo
>>because the limit on a solo still isn't braking "power".
>it wouldn't need to be as heavy weight, but bike brakes are light weight
>things, look at the disks very thin, there is a middle ground.

It would still be pointless for the reason above.
--
David Damerell <[email protected]> Kill the tomato!
Today is Leicesterday, August.