Why do some forks and frames have brake rotor size limits?
 

On Sat, 28 Oct 2017 08:09:28 -0700, Joerg
wrote:

On 2017-10-27 17:11, John B. wrote:
On Fri, 27 Oct 2017 06:58:27 -0700, Joerg
wrote:

On 2017-10-27 01:11, John B. wrote:
On Wed, 25 Oct 2017 07:53:11 -0700, Joerg
wrote:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

On 2017-10-24 07:27, wrote:
On Tuesday, October 24, 2017 at 2:19:48 AM UTC-7, John B. wrote:
On Mon, 23 Oct 2017 10:09:20 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 12:48:29 +0700, John B.
wrote:

On Sun, 22 Oct 2017 20:51:15 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 07:02:08 +0700, John B.
wrote:

But re disc brake cooling F1 car brakes appear to work with
the discs red hot. In the 1,000 degree (F) range. And they
use Carbon Fiber discs too :-) And everyone knows that CF
is better.

"Thermal Conductivity of Carbon Fiber, and other Carbon
Based Materials"
http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html


"So...Is Carbon Fiber a good heat conductor?
As usual the answer is "it depends." The short answer is NO
not when regular carbon fiber is made up in regular epoxy and
expected to conduct heat across the thickness. IF a highly
carbonized pan fiber with graphite or diamond added, is
measured for heat transmission in the length of the fiber it
is very good and can rival and exceed copper."

On the other hand, they seem to work pretty well :-) See
https://www.youtube.com/watch?v=h5JcHAEmIYM for a visual
indication of heat dissipation. :-)

Impressive. I'll assume it's a carbon-carbon rotor, since all F1
cars seem to using them.

Undoubtedly so. But if the advantage of "carbon" bikes can be
extolled that a carbon-carbon frame must have twice the bragging
rights :-)


http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/


(4 pages)
"A typical road car uses a cast iron brake disc with an organic
brake pad. In an F1 car, though, the same material is used for
both disc and pad, and this material is known as carbon-carbon -
a significantly different material to the carbon-fibre
composites used in the rest of the car" In other words, the F1
brakes are NOT made from CF.

Some detail on Formula 1 brakes:
https://www.youtube.com/watch?v=ev6XTdlKElw

Fun destroying brakes:
https://www.youtube.com/watch?v=KslGsXMgmqg The brake starting
at 4:45 sure looks like CF but I'm not sure.

Maybe twin disk brakes would be easier?
http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg


https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg
https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg


https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg
https://www.minibikecraze.co.uk/wp-content/uploads/bs0978.jpg
https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268

Given the coefficient of friction between a 1.25" wide rubber tire
(32mm) and a wet road probably dragging the feet will work. :-)

Joerg's experience is with full suspension MTB's. These things are
incredibly heavy and long wheelbased. He has his judgement of disks
and it is no doubt quite accurate for his experience and riding.

I have disks on a much lighter and shorter wheelbased bike. I know
the failings up close and personal. I simply cannot imagine WHY a
person would want a more complicated system than that offered by the
Campy Skeleton brakes.


The reason can be summed up in one word: Rain :-)

But last Sunday I started out my "weekend" ride in the rain. It had
been raining nearly all night and the roads had a lot of water on them
- note we have been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility wasn't working very well
and I rode 20 Km of a 30 Km ride in light rain and flooded roads in
many places. I was splashing through water in some places and cars
were splashing through (and splashing me) in others.

Of course, Sunday is much lighter traffic then on work days but still,
Bangkok is rated as one of the cities with the most chaotic traffic
in the world, and I did have to stop suddenly several time, on flooded
roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back brake stops me
somewhat slowly and front brake stops rather suddenly, both brakes
together provides best stopping. No long wait after grabbing a brake
lever although I did think of you with your stopping problems and I
have the feeling that the brake lever pressure might be a tiny bit
more to stop in the rain but if it was it was so little that it
couldn't be quantified.

But of course I am using quality brake pads. Why it costs me US$12.12
a wheel just for pads alone.... but they do last a year or more.


It seems Californian rain and Thai rain aren't the same. When it rains
heavily and I have to do a surprise emergency stop after not having used
the brakes for a while there is 1-2sec of nada, absolutely nothing. It
makes no difference whatsoever whether I use $17 high-falutin Koolstop
rain-rated pads or $4 Clarks pads. The experience of other riders around
here and in this NG is similar.

Which, to be honest, I find a little mystifying as I've had pretty
constant success with conventional brakes.

Frankly, I can't believe this is solely because I'm somehow so
uniquely skilled or that y'all are all in the awkward squad

I do see a number of people here and many who are not here who seem to
have ridden for years using conventional brakes without complaint and
some of the blogs I read don't even talk about brakes. Dave Moulton,
for example. An old fellow, used to race bikes, came to the U.S. in
about 1979 and built frames commercially for years, now retired, has
one entry in his blog about brakes - "centering side pull brakes".

Another blog from the long distance side of the bicycleing world, The
Blayleys, who are into Audex's and who apparently each ride in the
neighborhood of 10,000 miles annually, mentions Vee brakes in
reference to a Tandem while a photo of them on a tandem on their web
page shows disc brakes. On the other hand, when she discusses a "good
brevet bike she simply says that the "brakes must clear the fenders
and probably long reach caliper brakes will suffice".

In short, it seems that brakes just don't seem to be a hot subject in
much of the cycling fraternity.


To a large part that is because most cyclist will not ride in driving
rain. Some do and those know exactly how that delay with rim brakes
feels. Occasionally it is called "free fall" because that's how it feels
like.

Well, the Blayleys state that the husband, John, has ridden 10 - 17
thousand miles a year for the past 25 years and the wife, Pamela, has
ridden from 10 - 14 thousand miles a year for the past 20 years, or
another way to put it might be that together they have ridden from 20
- 30 thousand miles a year for the past 20 years.

Somehow I suspect that they may have encountered rain in that period.


And grandpa has driven his cars without safety belts yet survived ...


Well, since you mentioned it. My two grandfathers, neither of whom
ever had a road accident. One died at 92 and the other at 87. My
father never had a road accident although he did get a speeding ticket
once, died at 87. My mother had one "accident", a guy ran a red light
and tee-boned her car, no speeding tickets, died at 86. All deaths
were considered "natural".

Do you really believe that safety belts would have benefited them?

--
Cheers,

John B.

Why do some forks and frames have brake rotor size limits?
 

On Sun, 29 Oct 2017 07:53:49 +0700, John B.
wrote:

I was thinking of air brakes configured more like a bird's wings. When
folded they would provide a certain amount of streamlining for the
rear of the bike and when actuated have a substantial amount of
stopping power.

When I lived in Albany County, I used air brakes all the time. Sitting
up straight and spreading yourself out will slow you quite a lot.

Once I left the top of a hill at the same time as another rider -- he
tucked, I, less confident, sat up. He reached the bottom when I was
about half-way down. And I had better bearings.

In Kosciusko County, going too fast is hardly ever a problem.

--
Joy Beeson
joy beeson at comcast dot net
http://wlweather.net/PAGEJOY/

Why do some forks and frames have brake rotor size limits?
 

On Sat, 28 Oct 2017 15:12:37 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 06:23:59 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 03:54:43 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

I'm not sure that is correct. After all some old Greek guy was
supposed to have said, "Give me a lever and a place to stand and I
will move the earth". Nothing about being close.

No. I'm pretty certain I'm right here. Let's say that you can pull 100 lbs
on your brake lever and the lever has 2" of play before it hits your bars.
You can fiddle with leverage many places in the system, but the product of
that initial 100 lbs and 2" will be constant in the system. If the final
travel of the brake pads is 1/2", then you can apply 400 lbs force to the
pads. If you tighten up your tolerances such that the pads only have to
move 1/16", then you can increase the leverage to the point where you can
apply 3200 lbs force to the pads. In disk brake systems this reduction in
pad-disk distance allow the MA to be increased to compensate for the
decreased leverage of the disk on the wheel. The increases brake pad
pressure at a given bike deceleration is what gives disk brakes more
consistent performance in the wet.

Movement of the parts doesn't make any difference the efficiency is
the pressure applied to the brake lever versus the pressure applied to
the braking device, usually the pads themselves.

A lever that is 1 foot long and moves, lets say, one quarter of the
diameter of a 2 foot circle applies the same force to a load located 1
foot from the fulcrum as a 100 ft lever which moves 1/4 of the
diameter of a 200 ft circle applies to a load that is 100 ft. from the
fulcrum. The first lever moves 19 inches and the second moves 157
feet.

Sure. But the distance you can move your brake lever is limited by the
length of your fingers, and so the distance you can move at the lever end
is essentially fixed. To increase the mechanical advantage in THAT system,
you have to reduce the distance the brake pads move. No ifs, ands, buts or
maybes.

You are talking about two different things. Mechanical efficiency and
how long your fingers are.

They aren't really related.
--
Cheers,

John B.

Theoretically, the mechanical advantage of a brake system and the length of
your fingers aren't related, but practically, in this example of the
mechanical advantage of a bicycle brake system, the two quantities are
chained together at the ankles. You can't have high brake pad travel and
high mechanical advantage unless the travel of the brake lever is very
large, and human hand dimensions just won't allow that.

Well you can continue to equate mechanical advantage with long, or
short, fingers but it doesn't make it true :-)

But you keep talking about the large clearance between the rim brake
pads and the rim versus the disc pads and the disc which isn't
necessarily true.

I use brifters - Shimano STI brake&shifters - on two of my bikes and
considering the rather limited travel of the brake levers the pads
need to be fitted very closely to the rims, and of course, the rims
need to be very straight. The two bikes are about 1,000 km from where
I'm presently located so I'm going much by memory but I think that the
pad to rim clearance is about 1mm. The two bikes I have here both have
down tube shifting and the brake pad clearance is largely determined
by where I want the brake levers to be when the brakes are applied,
but measuring one bike shows that the clearance is about 6mm.

I can sense no appreciable difference in the pressure I feel against
my fingers when stopping any of the four bikes.
--
Cheers,

John B.

Why do some forks and frames have brake rotor size limits?
 

On Saturday, October 28, 2017 at 5:06:46 PM UTC-7, Joerg wrote:
On 2017-10-28 16:59, jbeattie wrote:
On Saturday, October 28, 2017 at 3:40:36 PM UTC-7, AMuzi wrote:
On 10/28/2017 4:27 PM, jbeattie wrote:
On Saturday, October 28, 2017 at 12:08:44 PM UTC-7, Sir Ridesalot
wrote:
On Saturday, October 28, 2017 at 11:09:18 AM UTC-4, Joerg
wrote:
On 2017-10-27 17:11, John B. wrote:
On Fri, 27 Oct 2017 06:58:27 -0700, Joerg
wrote:

On 2017-10-27 01:11, John B. wrote:
On Wed, 25 Oct 2017 07:53:11 -0700, Joerg
wrote:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

On 2017-10-24 07:27, wrote:
On Tuesday, October 24, 2017 at 2:19:48 AM
UTC-7, John B. wrote:
On Mon, 23 Oct 2017 10:09:20 -0700, Jeff
Liebermann wrote:

On Mon, 23 Oct 2017 12:48:29 +0700, John
B. wrote:

On Sun, 22 Oct 2017 20:51:15 -0700, Jeff
Liebermann wrote:

On Mon, 23 Oct 2017 07:02:08 +0700,
John B. wrote:

But re disc brake cooling F1 car
brakes appear to work with the discs
red hot. In the 1,000 degree (F)
range. And they use Carbon Fiber
discs too :-) And everyone knows that
CF is better.

"Thermal Conductivity of Carbon Fiber,
and other Carbon Based Materials"
http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html




"So...Is Carbon Fiber a good heat conductor?
As usual the answer is "it depends."
The short answer is NO not when regular
carbon fiber is made up in regular
epoxy and expected to conduct heat
across the thickness. IF a highly
carbonized pan fiber with graphite or
diamond added, is measured for heat
transmission in the length of the fiber
it is very good and can rival and
exceed copper."

On the other hand, they seem to work
pretty well :-) See
https://www.youtube.com/watch?v=h5JcHAEmIYM
for a visual indication of heat
dissipation. :-)

Impressive. I'll assume it's a
carbon-carbon rotor, since all F1 cars seem
to using them.

Undoubtedly so. But if the advantage of
"carbon" bikes can be extolled that a
carbon-carbon frame must have twice the
bragging rights :-)


http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/




(4 pages)
"A typical road car uses a cast iron brake
disc with an organic brake pad. In an F1
car, though, the same material is used for
both disc and pad, and this material is
known as carbon-carbon - a significantly
different material to the carbon-fibre
composites used in the rest of the car" In
other words, the F1 brakes are NOT made
from CF.

Some detail on Formula 1 brakes:
https://www.youtube.com/watch?v=ev6XTdlKElw



Fun destroying brakes:
https://www.youtube.com/watch?v=KslGsXMgmqg
The brake starting at 4:45 sure looks like
CF but I'm not sure.

Maybe twin disk brakes would be easier?
http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg




https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg
https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg




https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg
https://www.minibikecraze.co.uk/wp-content/uploads/bs0978..jpg


https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268

Given the coefficient of friction between a
1.25" wide rubber tire (32mm) and a wet road
probably dragging the feet will work. :-)

Joerg's experience is with full suspension
MTB's. These things are incredibly heavy and
long wheelbased. He has his judgement of disks
and it is no doubt quite accurate for his
experience and riding.

I have disks on a much lighter and shorter
wheelbased bike. I know the failings up close
and personal. I simply cannot imagine WHY a
person would want a more complicated system
than that offered by the Campy Skeleton
brakes.


The reason can be summed up in one word: Rain
:-)

But last Sunday I started out my "weekend" ride in
the rain. It had been raining nearly all night and
the roads had a lot of water on them - note we have
been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility
wasn't working very well and I rode 20 Km of a 30
Km ride in light rain and flooded roads in many
places. I was splashing through water in some
places and cars were splashing through (and
splashing me) in others.

Of course, Sunday is much lighter traffic then on
work days but still, Bangkok is rated as one of
the cities with the most chaotic traffic in the
world, and I did have to stop suddenly several
time, on flooded roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back
brake stops me somewhat slowly and front brake
stops rather suddenly, both brakes together
provides best stopping. No long wait after grabbing
a brake lever although I did think of you with your
stopping problems and I have the feeling that the
brake lever pressure might be a tiny bit more to
stop in the rain but if it was it was so little
that it couldn't be quantified.

But of course I am using quality brake pads. Why it
costs me US$12.12 a wheel just for pads alone....
but they do last a year or more.


It seems Californian rain and Thai rain aren't the
same. When it rains heavily and I have to do a
surprise emergency stop after not having used the
brakes for a while there is 1-2sec of nada,
absolutely nothing. It makes no difference whatsoever
whether I use $17 high-falutin Koolstop rain-rated
pads or $4 Clarks pads. The experience of other
riders around here and in this NG is similar.

Which, to be honest, I find a little mystifying as I've
had pretty constant success with conventional brakes.

Frankly, I can't believe this is solely because I'm
somehow so uniquely skilled or that y'all are all in
the awkward squad

I do see a number of people here and many who are not
here who seem to have ridden for years using
conventional brakes without complaint and some of the
blogs I read don't even talk about brakes. Dave
Moulton, for example. An old fellow, used to race
bikes, came to the U.S. in about 1979 and built frames
commercially for years, now retired, has one entry in
his blog about brakes - "centering side pull brakes".

Another blog from the long distance side of the
bicycleing world, The Blayleys, who are into Audex's
and who apparently each ride in the neighborhood of
10,000 miles annually, mentions Vee brakes in reference
to a Tandem while a photo of them on a tandem on their
web page shows disc brakes. On the other hand, when she
discusses a "good brevet bike she simply says that the
"brakes must clear the fenders and probably long reach
caliper brakes will suffice".

In short, it seems that brakes just don't seem to be a
hot subject in much of the cycling fraternity.


To a large part that is because most cyclist will not
ride in driving rain. Some do and those know exactly how
that delay with rim brakes feels. Occasionally it is
called "free fall" because that's how it feels like.

Well, the Blayleys state that the husband, John, has ridden
10 - 17 thousand miles a year for the past 25 years and the
wife, Pamela, has ridden from 10 - 14 thousand miles a year
for the past 20 years, or another way to put it might be
that together they have ridden from 20 - 30 thousand miles
a year for the past 20 years.

Somehow I suspect that they may have encountered rain in
that period.


And grandpa has driven his cars without safety belts yet
survived ...

For people who do not shy away from unpaved roads or use a
lot of singletrack and ride in the rain there is a much more
extreme issue: Wet mud. You may have never encountered it but
I have many times. You reach in and, after a second or two of
nothing, the rim brakes come on but let off an awful grinding
noise. You can literally hear the rim being tortured but
because of a rapidly approaching curve you can't let go. As I
have mentioned before the rims on my old MTB are only 1000mi
old but the front rim is almost shot from all that. Deep
grooves.

I stand by my opinion that rim brakes are fair weather
brakes. Then they are fine but not when the going gets tough.
Like this kind of weather:

https://www.youtube.com/watch?v=mX_EKybzK4Y


I might comment that I've ridden coaster brakes, drum
brakes, rod pull brakes, cantilever brakes, side pull
single pivot caliper brakes, double pivot caliper, Vee
brakes and for one short ride a cable disc brake. and
at the time I rode them I found all the brakes to give
acceptable service. Well with one exception, rim brakes
and chrome plated steel rims were sometimes a bit iffy
:-)


Yes, those were the worst. It got a little better with
aluminum rims but not a lot. In the world of automotive
such a brake "system" would not stand the slightest
change of being legal.

Finally after many decades the bicycle industry woke up
and adopted what the automotive guys had all along, disc
brakes. Why should I accept an inferior brake system on a
new bike when there is a much better one?

Well, when I worked on airplanes I remember that the F-4
had multi plate disc brakes which provided a tremendous
amount of stopping power in a very small package.


Some tandems have that as well, and of course motorcycles:
Two discs up front. But not stacks of discs.


One supposes that will be next big improvement in bicycle
brakes. Or perhaps a drag chute for those long downhill's
to keep the rims from melting?


I've thought about it :-)

-- Regards, Joerg

http://www.analogconsultants.com/

Oh ****! I've ridden many hundreds of miles off road in dry and
wet sand, mud, heavy rain, rutted roads/trails and did so on an
MTB with cantilever brakes and NEVER had trouble stopping
either when I needed to or when I wanted too. I've ridden on
ice and in 4 inches+ deep snowand also never had trouble
stopping.

Perhaps you ride too fast for the conditions/sight lines or you
don't keep your brakes adjusted properly.

Really? I have trouble standing up on ice. There is a point at
which you don't want super-strong brakes.

-- Jay Beattie.


Yeah me too. Snow is one thing - I'm used to that- but ice is
quite another. Depending on the recent weather, a frozen slick
patch of ice under snow will dump me right on my ass. We mere
humans would have some trouble with Jobst's famous tour down a
frozen Swiss river.

I live at a whopping 400 feet (about) elevation. The garage in my
building is probably 0 feet. That minor elevation change sometimes
means the difference between ice and no ice -- so I walk outside in
the morning and say f*** this! And then I jump in the car and
half-way to work, creeping along in traffic, there is no ice -- and
then I regret not riding. So, in order to avoid that regret, I have
done some pretty stupid sh** spinning around on ice or hoofing it in
my SPDs to get out of my neighborhood and then being freaked out
riding over the slick bridges and viaducts into town. I met up with
another guy on a bike who was fish-tailing down the road on one of
those mornings, and we looked at each other and shook our heads --
"we're a couple of idiots." So, now I'm working on not feeling regret
or guilt if I drive. And don't get me going about the dopes who jump
into their Malibus with no-season/no-tread tires and crash on the ice
and/or snow. I'll slap on the snow tires in November. I really miss
studs, but I'm doing penance with studless.


Can't you get studded tires for your bike? Nokian Hakkapeliitta from
Finland or similar.

--
Regards, Joerg

http://www.analogconsultants.com/


I have some crappy Innova studs. They are no guaranty of remaining upright.. Snow and ice are one thing. Freezing rain and sheet ice are another. Even with studs, your wheels can get away from you, and when you hit ice on metal -- like street car and MAX tracks or manhole covers, all bets are off. With that said, odds are better with studs. I do put them on if we're looking at an extended period of snow and/or ice. Portland is not the mid-west, so snow does not stick around very long, and when its fresh, I just ride on CX tires or gravel bike tires. Sometimes, it falls unexpectedly when I'm at work. The town shuts down with all the dopes spinning around in cars (Portland drivers are hysterical in fresh snow), and I just roll right by one whatever tires happen to be on my bike that day. Now, day two or three or four . . . forget it. When it refreezes, it's almost impossible to ride -- or possible but very not fun.

-- Jay Beattie.

Why do some forks and frames have brake rotor size limits?
 

On Sat, 28 Oct 2017 10:32:45 -0700, Jeff Liebermann
wrote:

On Sat, 28 Oct 2017 13:57:05 +0700, John B.
wrote:
Actually, after giving it a bit of thought, I would think that
something like the so called "air brakes" used on some aircraft might
be more practical. they could be operated either by cable or
hydraulics and could be self retracting when not needed.
https://www.preciseflight.com/genera...p/speedbrakes/

Yep. How about a pyramid shaped drag chute? 4 sides of the pyramid
are independent and hinged at the base of the pyramid. The 4 points
of each side come together and are controlled by shroud lines. Pull
on the shroud lines, the 4 peaks come together, and the pyramid acts
like a drag chute. Release the shroud lines, the 4 sides open up, and
the drag is greatly reduced.

Sitting in the mud repacking your drag chute every time you touched
the brake lever might be a bit off putting :-)

That's not really so bad as long as one uses the drag chute only for
an emergency stop. Kinda like that use-once air bag.

As long as you're willing to install a parachute, how about a wing,
parasail, or similar airfoil? Instead of using it to stop the
bicycle, it would provide sufficient lift for the bicycle to go over
obstructions and road hazards.
https://www.google.com/search?q=flying+bicycle&tbm=isch
Only $45,000:
https://www.hammacher.com/Product/12187
It's a bird. It's a plane. It's a biycle?

Maybe just add some permanent aerodynamic drag? At low speeds, it
won't have much effect, but will put an upper limit on the air, err...
ground speed. Something like this:
http://boxercycles.com/wp-content/uploads/2015/01/BN_RocketElectricTrike_014.jpg
http://boxercycles.com/product/rocket/
Nice name. Nice crumple zone.
Only £4,950.00

If you really want to stop quickly, what you need is a retro-rocket.
Normally, the rocket is used to propel the bicycle in the forward
direction. However, for this contrivance, the rocket is used to slow
down the bicycle. Simply attach one of my "Instant Stop Retro Rocket
Brake" systems onto the frame. If you find yourself speeding out of
control in the general direction of an immovable obstruction, merely
press the "stop" button. The rocket will fire forward and bring the
bicycle to a sudden halt. It might also incinerate the obstruction,
but that can be dealt with in court. Soon, everyone will be using
"Rocket Brakes".

I was thinking of air brakes configured more like a bird's wings. When
folded they would provide a certain amount of streamlining for the
rear of the bike and when actuated have a substantial amount of
stopping power.

But taking your idea to heart, they could easily have an adjustable
angle of attack and so could also provide lift under certain
conditions.

A problem with the rocket braking is forward speed versus rocket
thrust. A rocket that would bring you to a stop at, oh say 50 mph,
would have a very different effect at, say 10 mph.
--
Cheers,

John B.

Why do some forks and frames have brake rotor size limits?
 

On Sat, 28 Oct 2017 17:40:36 -0500, AMuzi wrote:

On 10/28/2017 4:27 PM, jbeattie wrote:
On Saturday, October 28, 2017 at 12:08:44 PM UTC-7, Sir Ridesalot wrote:
On Saturday, October 28, 2017 at 11:09:18 AM UTC-4, Joerg wrote:
On 2017-10-27 17:11, John B. wrote:
On Fri, 27 Oct 2017 06:58:27 -0700, Joerg
wrote:

On 2017-10-27 01:11, John B. wrote:
On Wed, 25 Oct 2017 07:53:11 -0700, Joerg
wrote:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

On 2017-10-24 07:27, wrote:
On Tuesday, October 24, 2017 at 2:19:48 AM UTC-7, John B. wrote:
On Mon, 23 Oct 2017 10:09:20 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 12:48:29 +0700, John B.
wrote:

On Sun, 22 Oct 2017 20:51:15 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 07:02:08 +0700, John B.
wrote:

But re disc brake cooling F1 car brakes appear to work with
the discs red hot. In the 1,000 degree (F) range. And they
use Carbon Fiber discs too :-) And everyone knows that CF
is better.

"Thermal Conductivity of Carbon Fiber, and other Carbon
Based Materials"
http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html


"So...Is Carbon Fiber a good heat conductor?
As usual the answer is "it depends." The short answer is NO
not when regular carbon fiber is made up in regular epoxy and
expected to conduct heat across the thickness. IF a highly
carbonized pan fiber with graphite or diamond added, is
measured for heat transmission in the length of the fiber it
is very good and can rival and exceed copper."

On the other hand, they seem to work pretty well :-) See
https://www.youtube.com/watch?v=h5JcHAEmIYM for a visual
indication of heat dissipation. :-)

Impressive. I'll assume it's a carbon-carbon rotor, since all F1
cars seem to using them.

Undoubtedly so. But if the advantage of "carbon" bikes can be
extolled that a carbon-carbon frame must have twice the bragging
rights :-)


http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/


(4 pages)
"A typical road car uses a cast iron brake disc with an organic
brake pad. In an F1 car, though, the same material is used for
both disc and pad, and this material is known as carbon-carbon -
a significantly different material to the carbon-fibre
composites used in the rest of the car" In other words, the F1
brakes are NOT made from CF.

Some detail on Formula 1 brakes:
https://www.youtube.com/watch?v=ev6XTdlKElw

Fun destroying brakes:
https://www.youtube.com/watch?v=KslGsXMgmqg The brake starting
at 4:45 sure looks like CF but I'm not sure.

Maybe twin disk brakes would be easier?
http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg


https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg
https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg


https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg
https://www.minibikecraze.co.uk/wp-content/uploads/bs0978.jpg
https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268

Given the coefficient of friction between a 1.25" wide rubber tire
(32mm) and a wet road probably dragging the feet will work. :-)

Joerg's experience is with full suspension MTB's. These things are
incredibly heavy and long wheelbased. He has his judgement of disks
and it is no doubt quite accurate for his experience and riding.

I have disks on a much lighter and shorter wheelbased bike. I know
the failings up close and personal. I simply cannot imagine WHY a
person would want a more complicated system than that offered by the
Campy Skeleton brakes.


The reason can be summed up in one word: Rain :-)

But last Sunday I started out my "weekend" ride in the rain. It had
been raining nearly all night and the roads had a lot of water on them
- note we have been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility wasn't working very well
and I rode 20 Km of a 30 Km ride in light rain and flooded roads in
many places. I was splashing through water in some places and cars
were splashing through (and splashing me) in others.

Of course, Sunday is much lighter traffic then on work days but still,
Bangkok is rated as one of the cities with the most chaotic traffic
in the world, and I did have to stop suddenly several time, on flooded
roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back brake stops me
somewhat slowly and front brake stops rather suddenly, both brakes
together provides best stopping. No long wait after grabbing a brake
lever although I did think of you with your stopping problems and I
have the feeling that the brake lever pressure might be a tiny bit
more to stop in the rain but if it was it was so little that it
couldn't be quantified.

But of course I am using quality brake pads. Why it costs me US$12.12
a wheel just for pads alone.... but they do last a year or more.


It seems Californian rain and Thai rain aren't the same. When it rains
heavily and I have to do a surprise emergency stop after not having used
the brakes for a while there is 1-2sec of nada, absolutely nothing. It
makes no difference whatsoever whether I use $17 high-falutin Koolstop
rain-rated pads or $4 Clarks pads. The experience of other riders around
here and in this NG is similar.

Which, to be honest, I find a little mystifying as I've had pretty
constant success with conventional brakes.

Frankly, I can't believe this is solely because I'm somehow so
uniquely skilled or that y'all are all in the awkward squad

I do see a number of people here and many who are not here who seem to
have ridden for years using conventional brakes without complaint and
some of the blogs I read don't even talk about brakes. Dave Moulton,
for example. An old fellow, used to race bikes, came to the U.S. in
about 1979 and built frames commercially for years, now retired, has
one entry in his blog about brakes - "centering side pull brakes".

Another blog from the long distance side of the bicycleing world, The
Blayleys, who are into Audex's and who apparently each ride in the
neighborhood of 10,000 miles annually, mentions Vee brakes in
reference to a Tandem while a photo of them on a tandem on their web
page shows disc brakes. On the other hand, when she discusses a "good
brevet bike she simply says that the "brakes must clear the fenders
and probably long reach caliper brakes will suffice".

In short, it seems that brakes just don't seem to be a hot subject in
much of the cycling fraternity.


To a large part that is because most cyclist will not ride in driving
rain. Some do and those know exactly how that delay with rim brakes
feels. Occasionally it is called "free fall" because that's how it feels
like.

Well, the Blayleys state that the husband, John, has ridden 10 - 17
thousand miles a year for the past 25 years and the wife, Pamela, has
ridden from 10 - 14 thousand miles a year for the past 20 years, or
another way to put it might be that together they have ridden from 20
- 30 thousand miles a year for the past 20 years.

Somehow I suspect that they may have encountered rain in that period.


And grandpa has driven his cars without safety belts yet survived ...

For people who do not shy away from unpaved roads or use a lot of
singletrack and ride in the rain there is a much more extreme issue: Wet
mud. You may have never encountered it but I have many times. You reach
in and, after a second or two of nothing, the rim brakes come on but let
off an awful grinding noise. You can literally hear the rim being
tortured but because of a rapidly approaching curve you can't let go. As
I have mentioned before the rims on my old MTB are only 1000mi old but
the front rim is almost shot from all that. Deep grooves.

I stand by my opinion that rim brakes are fair weather brakes. Then they
are fine but not when the going gets tough. Like this kind of weather:

https://www.youtube.com/watch?v=mX_EKybzK4Y


I might comment that I've ridden coaster brakes, drum brakes, rod pull
brakes, cantilever brakes, side pull single pivot caliper brakes,
double pivot caliper, Vee brakes and for one short ride a cable disc
brake. and at the time I rode them I found all the brakes to give
acceptable service. Well with one exception, rim brakes and chrome
plated steel rims were sometimes a bit iffy :-)


Yes, those were the worst. It got a little better with aluminum rims but
not a lot. In the world of automotive such a brake "system" would not
stand the slightest change of being legal.

Finally after many decades the bicycle industry woke up and adopted what
the automotive guys had all along, disc brakes. Why should I accept an
inferior brake system on a new bike when there is a much better one?

Well, when I worked on airplanes I remember that the F-4 had multi
plate disc brakes which provided a tremendous amount of stopping power
in a very small package.


Some tandems have that as well, and of course motorcycles: Two discs up
front. But not stacks of discs.


One supposes that will be next big improvement in bicycle brakes. Or
perhaps a drag chute for those long downhill's to keep the rims from
melting?


I've thought about it :-)

--
Regards, Joerg

http://www.analogconsultants.com/

Oh ****! I've ridden many hundreds of miles off road in dry and wet sand, mud, heavy rain, rutted roads/trails and did so on an MTB with cantilever brakes and NEVER had trouble stopping either when I needed to or when I wanted too. I've ridden on ice and in 4 inches+ deep snowand also never had trouble stopping.

Perhaps you ride too fast for the conditions/sight lines or you don't keep your brakes adjusted properly.

Really? I have trouble standing up on ice. There is a point at which you don't want super-strong brakes.

-- Jay Beattie.


Yeah me too.
Snow is one thing - I'm used to that- but ice is quite
another. Depending on the recent weather, a frozen slick
patch of ice under snow will dump me right on my ass. We
mere humans would have some trouble with Jobst's famous tour
down a frozen Swiss river.

I've never ridden a bicycle on ice or snow but wouldn't studded tires
serve? Either
http://www.peterwhitecycles.com/studdedtires.php
or for severe conditions
https://www.youtube.com/watch?v=sQ4kufaQ-lg
--
Cheers,

John B.

Why do some forks and frames have brake rotor size limits?
 

On Sat, 28 Oct 2017 16:59:47 -0700 (PDT), jbeattie
wrote:

On Saturday, October 28, 2017 at 3:40:36 PM UTC-7, AMuzi wrote:
On 10/28/2017 4:27 PM, jbeattie wrote:
On Saturday, October 28, 2017 at 12:08:44 PM UTC-7, Sir Ridesalot wrote:
On Saturday, October 28, 2017 at 11:09:18 AM UTC-4, Joerg wrote:
On 2017-10-27 17:11, John B. wrote:
On Fri, 27 Oct 2017 06:58:27 -0700, Joerg
wrote:

On 2017-10-27 01:11, John B. wrote:
On Wed, 25 Oct 2017 07:53:11 -0700, Joerg
wrote:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

On 2017-10-24 07:27, wrote:
On Tuesday, October 24, 2017 at 2:19:48 AM UTC-7, John B. wrote:
On Mon, 23 Oct 2017 10:09:20 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 12:48:29 +0700, John B.
wrote:

On Sun, 22 Oct 2017 20:51:15 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 07:02:08 +0700, John B.
wrote:

But re disc brake cooling F1 car brakes appear to work with
the discs red hot. In the 1,000 degree (F) range. And they
use Carbon Fiber discs too :-) And everyone knows that CF
is better.

"Thermal Conductivity of Carbon Fiber, and other Carbon
Based Materials"
http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html


"So...Is Carbon Fiber a good heat conductor?
As usual the answer is "it depends." The short answer is NO
not when regular carbon fiber is made up in regular epoxy and
expected to conduct heat across the thickness. IF a highly
carbonized pan fiber with graphite or diamond added, is
measured for heat transmission in the length of the fiber it
is very good and can rival and exceed copper."

On the other hand, they seem to work pretty well :-) See
https://www.youtube.com/watch?v=h5JcHAEmIYM for a visual
indication of heat dissipation. :-)

Impressive. I'll assume it's a carbon-carbon rotor, since all F1
cars seem to using them.

Undoubtedly so. But if the advantage of "carbon" bikes can be
extolled that a carbon-carbon frame must have twice the bragging
rights :-)


http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/


(4 pages)
"A typical road car uses a cast iron brake disc with an organic
brake pad. In an F1 car, though, the same material is used for
both disc and pad, and this material is known as carbon-carbon -
a significantly different material to the carbon-fibre
composites used in the rest of the car" In other words, the F1
brakes are NOT made from CF.

Some detail on Formula 1 brakes:
https://www.youtube.com/watch?v=ev6XTdlKElw

Fun destroying brakes:
https://www.youtube.com/watch?v=KslGsXMgmqg The brake starting
at 4:45 sure looks like CF but I'm not sure.

Maybe twin disk brakes would be easier?
http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg


https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg
https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg


https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg
https://www.minibikecraze.co.uk/wp-content/uploads/bs0978.jpg
https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268

Given the coefficient of friction between a 1.25" wide rubber tire
(32mm) and a wet road probably dragging the feet will work. :-)

Joerg's experience is with full suspension MTB's. These things are
incredibly heavy and long wheelbased. He has his judgement of disks
and it is no doubt quite accurate for his experience and riding.

I have disks on a much lighter and shorter wheelbased bike. I know
the failings up close and personal. I simply cannot imagine WHY a
person would want a more complicated system than that offered by the
Campy Skeleton brakes.


The reason can be summed up in one word: Rain :-)

But last Sunday I started out my "weekend" ride in the rain. It had
been raining nearly all night and the roads had a lot of water on them
- note we have been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility wasn't working very well
and I rode 20 Km of a 30 Km ride in light rain and flooded roads in
many places. I was splashing through water in some places and cars
were splashing through (and splashing me) in others.

Of course, Sunday is much lighter traffic then on work days but still,
Bangkok is rated as one of the cities with the most chaotic traffic
in the world, and I did have to stop suddenly several time, on flooded
roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back brake stops me
somewhat slowly and front brake stops rather suddenly, both brakes
together provides best stopping. No long wait after grabbing a brake
lever although I did think of you with your stopping problems and I
have the feeling that the brake lever pressure might be a tiny bit
more to stop in the rain but if it was it was so little that it
couldn't be quantified.

But of course I am using quality brake pads. Why it costs me US$12.12
a wheel just for pads alone.... but they do last a year or more.


It seems Californian rain and Thai rain aren't the same. When it rains
heavily and I have to do a surprise emergency stop after not having used
the brakes for a while there is 1-2sec of nada, absolutely nothing. It
makes no difference whatsoever whether I use $17 high-falutin Koolstop
rain-rated pads or $4 Clarks pads. The experience of other riders around
here and in this NG is similar.

Which, to be honest, I find a little mystifying as I've had pretty
constant success with conventional brakes.

Frankly, I can't believe this is solely because I'm somehow so
uniquely skilled or that y'all are all in the awkward squad

I do see a number of people here and many who are not here who seem to
have ridden for years using conventional brakes without complaint and
some of the blogs I read don't even talk about brakes. Dave Moulton,
for example. An old fellow, used to race bikes, came to the U.S. in
about 1979 and built frames commercially for years, now retired, has
one entry in his blog about brakes - "centering side pull brakes".

Another blog from the long distance side of the bicycleing world, The
Blayleys, who are into Audex's and who apparently each ride in the
neighborhood of 10,000 miles annually, mentions Vee brakes in
reference to a Tandem while a photo of them on a tandem on their web
page shows disc brakes. On the other hand, when she discusses a "good
brevet bike she simply says that the "brakes must clear the fenders
and probably long reach caliper brakes will suffice".

In short, it seems that brakes just don't seem to be a hot subject in
much of the cycling fraternity.


To a large part that is because most cyclist will not ride in driving
rain. Some do and those know exactly how that delay with rim brakes
feels. Occasionally it is called "free fall" because that's how it feels
like.

Well, the Blayleys state that the husband, John, has ridden 10 - 17
thousand miles a year for the past 25 years and the wife, Pamela, has
ridden from 10 - 14 thousand miles a year for the past 20 years, or
another way to put it might be that together they have ridden from 20
- 30 thousand miles a year for the past 20 years.

Somehow I suspect that they may have encountered rain in that period.


And grandpa has driven his cars without safety belts yet survived ...

For people who do not shy away from unpaved roads or use a lot of
singletrack and ride in the rain there is a much more extreme issue: Wet
mud. You may have never encountered it but I have many times. You reach
in and, after a second or two of nothing, the rim brakes come on but let
off an awful grinding noise. You can literally hear the rim being
tortured but because of a rapidly approaching curve you can't let go. As
I have mentioned before the rims on my old MTB are only 1000mi old but
the front rim is almost shot from all that. Deep grooves.

I stand by my opinion that rim brakes are fair weather brakes. Then they
are fine but not when the going gets tough. Like this kind of weather:

https://www.youtube.com/watch?v=mX_EKybzK4Y


I might comment that I've ridden coaster brakes, drum brakes, rod pull
brakes, cantilever brakes, side pull single pivot caliper brakes,
double pivot caliper, Vee brakes and for one short ride a cable disc
brake. and at the time I rode them I found all the brakes to give
acceptable service. Well with one exception, rim brakes and chrome
plated steel rims were sometimes a bit iffy :-)


Yes, those were the worst. It got a little better with aluminum rims but
not a lot. In the world of automotive such a brake "system" would not
stand the slightest change of being legal.

Finally after many decades the bicycle industry woke up and adopted what
the automotive guys had all along, disc brakes. Why should I accept an
inferior brake system on a new bike when there is a much better one?

Well, when I worked on airplanes I remember that the F-4 had multi
plate disc brakes which provided a tremendous amount of stopping power
in a very small package.


Some tandems have that as well, and of course motorcycles: Two discs up
front. But not stacks of discs.


One supposes that will be next big improvement in bicycle brakes. Or
perhaps a drag chute for those long downhill's to keep the rims from
melting?


I've thought about it :-)

--
Regards, Joerg

http://www.analogconsultants.com/

Oh ****! I've ridden many hundreds of miles off road in dry and wet sand, mud, heavy rain, rutted roads/trails and did so on an MTB with cantilever brakes and NEVER had trouble stopping either when I needed to or when I wanted too. I've ridden on ice and in 4 inches+ deep snowand also never had trouble stopping.

Perhaps you ride too fast for the conditions/sight lines or you don't keep your brakes adjusted properly.

Really? I have trouble standing up on ice. There is a point at which you don't want super-strong brakes.

-- Jay Beattie.


Yeah me too.
Snow is one thing - I'm used to that- but ice is quite
another. Depending on the recent weather, a frozen slick
patch of ice under snow will dump me right on my ass. We
mere humans would have some trouble with Jobst's famous tour
down a frozen Swiss river.

I live at a whopping 400 feet (about) elevation. The garage in my building is probably 0 feet. That minor elevation change sometimes means the difference between ice and no ice -- so I walk outside in the morning and say f*** this! And then I jump in the car and half-way to work, creeping along in traffic, there is no ice -- and then I regret not riding. So, in order to avoid that regret, I have done some pretty stupid sh** spinning around on ice or hoofing it in my SPDs to get out of my neighborhood and then being freaked out riding over the slick bridges and viaducts into town. I met up with another guy on a bike who was fish-tailing down the road on one of those mornings, and we looked at each other and shook our heads -- "we're a couple of idiots." So, now I'm working on not feeling regret or guilt if I drive. And don't get me going about the dopes who jump into their Malibus with no-season/no-tread tires and crash on the ice and/or snow. I'll slap on the snow tires in
November. I really miss studs, but I'm doing penance with studless.

-- Jay Beattie.

Are studded auto tires legal? I seem to remember that back in the
1960's when I was in Maine that it was illegal to drive studded tires
on bare roads. It was a long time ago and memory is always
questionable but I'm sure that I remember people getting a ticket for
using studded tires under certain conditions.

--
Cheers,

John B.

Why do some forks and frames have brake rotor size limits?
 

John B. wrote:
On Sat, 28 Oct 2017 15:12:37 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 06:23:59 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 03:54:43 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

I'm not sure that is correct. After all some old Greek guy was
supposed to have said, "Give me a lever and a place to stand and I
will move the earth". Nothing about being close.

No. I'm pretty certain I'm right here. Let's say that you can pull 100 lbs
on your brake lever and the lever has 2" of play before it hits your bars.
You can fiddle with leverage many places in the system, but the product of
that initial 100 lbs and 2" will be constant in the system. If the final
travel of the brake pads is 1/2", then you can apply 400 lbs force to the
pads. If you tighten up your tolerances such that the pads only have to
move 1/16", then you can increase the leverage to the point where you can
apply 3200 lbs force to the pads. In disk brake systems this reduction in
pad-disk distance allow the MA to be increased to compensate for the
decreased leverage of the disk on the wheel. The increases brake pad
pressure at a given bike deceleration is what gives disk brakes more
consistent performance in the wet.

Movement of the parts doesn't make any difference the efficiency is
the pressure applied to the brake lever versus the pressure applied to
the braking device, usually the pads themselves.

A lever that is 1 foot long and moves, lets say, one quarter of the
diameter of a 2 foot circle applies the same force to a load located 1
foot from the fulcrum as a 100 ft lever which moves 1/4 of the
diameter of a 200 ft circle applies to a load that is 100 ft. from the
fulcrum. The first lever moves 19 inches and the second moves 157
feet.

Sure. But the distance you can move your brake lever is limited by the
length of your fingers, and so the distance you can move at the lever end
is essentially fixed. To increase the mechanical advantage in THAT system,
you have to reduce the distance the brake pads move. No ifs, ands, buts or
maybes.

You are talking about two different things. Mechanical efficiency and
how long your fingers are.

They aren't really related.
--
Cheers,

John B.

Theoretically, the mechanical advantage of a brake system and the length of
your fingers aren't related, but practically, in this example of the
mechanical advantage of a bicycle brake system, the two quantities are
chained together at the ankles. You can't have high brake pad travel and
high mechanical advantage unless the travel of the brake lever is very
large, and human hand dimensions just won't allow that.

Well you can continue to equate mechanical advantage with long, or
short, fingers but it doesn't make it true :-)

But you keep talking about the large clearance between the rim brake
pads and the rim versus the disc pads and the disc which isn't
necessarily true.

I use brifters - Shimano STI brake&shifters - on two of my bikes and
considering the rather limited travel of the brake levers the pads
need to be fitted very closely to the rims, and of course, the rims
need to be very straight. The two bikes are about 1,000 km from where
I'm presently located so I'm going much by memory but I think that the
pad to rim clearance is about 1mm. The two bikes I have here both have
down tube shifting and the brake pad clearance is largely determined
by where I want the brake levers to be when the brakes are applied,
but measuring one bike shows that the clearance is about 6mm.

I can sense no appreciable difference in the pressure I feel against
my fingers when stopping any of the four bikes.
--
Cheers,

John B.

I think we're pretty close to a standoff here, so I'll invoke the name of
Sheldon, and then give up. Read through

https://www.sheldonbrown.com/cantilever-geometry.html

and tell me if it changes your opinion about what I've been saying.

To summarize my position
1) The mechanical advantage of a brake system (ie: the ratio of pad force
to lever force) is the inverse of the ratio of pad travel to lever travel.

2) bike brakes are made for humans and not orangutans or aliens, so they
all tend to have about the same amount of lever travel.

3) because of 1 and 2, the travel of the brake pad is pretty much inversely
proportional to the mechanical advantage.

4) because of 1, 2 and the fact that brakes need to actually touch the
rim/disk in order to work, the mechanical advantage of a bicycle brake
system is approximately inversely proportional to how far you can set the
pads away from the rim/disk and still have the system work (non-linear
systems excepted).

If you still doubt what I say, you may have to continue the discussion with
somebody else, as I have obviously failed in my attempts to communicate.

Why do some forks and frames have brake rotor size limits?
 

On 10/28/2017 9:06 PM, John B. wrote:
On Sat, 28 Oct 2017 17:40:36 -0500, AMuzi wrote:

On 10/28/2017 4:27 PM, jbeattie wrote:
On Saturday, October 28, 2017 at 12:08:44 PM UTC-7, Sir Ridesalot wrote:
On Saturday, October 28, 2017 at 11:09:18 AM UTC-4, Joerg wrote:
On 2017-10-27 17:11, John B. wrote:
On Fri, 27 Oct 2017 06:58:27 -0700, Joerg
wrote:

On 2017-10-27 01:11, John B. wrote:
On Wed, 25 Oct 2017 07:53:11 -0700, Joerg
wrote:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

On 2017-10-24 07:27, wrote:
On Tuesday, October 24, 2017 at 2:19:48 AM UTC-7, John B. wrote:
On Mon, 23 Oct 2017 10:09:20 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 12:48:29 +0700, John B.
wrote:

On Sun, 22 Oct 2017 20:51:15 -0700, Jeff Liebermann
wrote:

On Mon, 23 Oct 2017 07:02:08 +0700, John B.
wrote:

But re disc brake cooling F1 car brakes appear to work with
the discs red hot. In the 1,000 degree (F) range. And they
use Carbon Fiber discs too :-) And everyone knows that CF
is better.

"Thermal Conductivity of Carbon Fiber, and other Carbon
Based Materials"
http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html


"So...Is Carbon Fiber a good heat conductor?
As usual the answer is "it depends." The short answer is NO
not when regular carbon fiber is made up in regular epoxy and
expected to conduct heat across the thickness. IF a highly
carbonized pan fiber with graphite or diamond added, is
measured for heat transmission in the length of the fiber it
is very good and can rival and exceed copper."

On the other hand, they seem to work pretty well :-) See
https://www.youtube.com/watch?v=h5JcHAEmIYM for a visual
indication of heat dissipation. :-)

Impressive. I'll assume it's a carbon-carbon rotor, since all F1
cars seem to using them.

Undoubtedly so. But if the advantage of "carbon" bikes can be
extolled that a carbon-carbon frame must have twice the bragging
rights :-)


http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/


(4 pages)
"A typical road car uses a cast iron brake disc with an organic
brake pad. In an F1 car, though, the same material is used for
both disc and pad, and this material is known as carbon-carbon -
a significantly different material to the carbon-fibre
composites used in the rest of the car" In other words, the F1
brakes are NOT made from CF.

Some detail on Formula 1 brakes:
https://www.youtube.com/watch?v=ev6XTdlKElw

Fun destroying brakes:
https://www.youtube.com/watch?v=KslGsXMgmqg The brake starting
at 4:45 sure looks like CF but I'm not sure.

Maybe twin disk brakes would be easier?
http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg


https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg
https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg


https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg
https://www.minibikecraze.co.uk/wp-content/uploads/bs0978.jpg
https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268

Given the coefficient of friction between a 1.25" wide rubber tire
(32mm) and a wet road probably dragging the feet will work. :-)

Joerg's experience is with full suspension MTB's. These things are
incredibly heavy and long wheelbased. He has his judgement of disks
and it is no doubt quite accurate for his experience and riding.

I have disks on a much lighter and shorter wheelbased bike. I know
the failings up close and personal. I simply cannot imagine WHY a
person would want a more complicated system than that offered by the
Campy Skeleton brakes.


The reason can be summed up in one word: Rain :-)

But last Sunday I started out my "weekend" ride in the rain. It had
been raining nearly all night and the roads had a lot of water on them
- note we have been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility wasn't working very well
and I rode 20 Km of a 30 Km ride in light rain and flooded roads in
many places. I was splashing through water in some places and cars
were splashing through (and splashing me) in others.

Of course, Sunday is much lighter traffic then on work days but still,
Bangkok is rated as one of the cities with the most chaotic traffic
in the world, and I did have to stop suddenly several time, on flooded
roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back brake stops me
somewhat slowly and front brake stops rather suddenly, both brakes
together provides best stopping. No long wait after grabbing a brake
lever although I did think of you with your stopping problems and I
have the feeling that the brake lever pressure might be a tiny bit
more to stop in the rain but if it was it was so little that it
couldn't be quantified.

But of course I am using quality brake pads. Why it costs me US$12.12
a wheel just for pads alone.... but they do last a year or more.


It seems Californian rain and Thai rain aren't the same. When it rains
heavily and I have to do a surprise emergency stop after not having used
the brakes for a while there is 1-2sec of nada, absolutely nothing. It
makes no difference whatsoever whether I use $17 high-falutin Koolstop
rain-rated pads or $4 Clarks pads. The experience of other riders around
here and in this NG is similar.

Which, to be honest, I find a little mystifying as I've had pretty
constant success with conventional brakes.

Frankly, I can't believe this is solely because I'm somehow so
uniquely skilled or that y'all are all in the awkward squad

I do see a number of people here and many who are not here who seem to
have ridden for years using conventional brakes without complaint and
some of the blogs I read don't even talk about brakes. Dave Moulton,
for example. An old fellow, used to race bikes, came to the U.S. in
about 1979 and built frames commercially for years, now retired, has
one entry in his blog about brakes - "centering side pull brakes".

Another blog from the long distance side of the bicycleing world, The
Blayleys, who are into Audex's and who apparently each ride in the
neighborhood of 10,000 miles annually, mentions Vee brakes in
reference to a Tandem while a photo of them on a tandem on their web
page shows disc brakes. On the other hand, when she discusses a "good
brevet bike she simply says that the "brakes must clear the fenders
and probably long reach caliper brakes will suffice".

In short, it seems that brakes just don't seem to be a hot subject in
much of the cycling fraternity.


To a large part that is because most cyclist will not ride in driving
rain. Some do and those know exactly how that delay with rim brakes
feels. Occasionally it is called "free fall" because that's how it feels
like.

Well, the Blayleys state that the husband, John, has ridden 10 - 17
thousand miles a year for the past 25 years and the wife, Pamela, has
ridden from 10 - 14 thousand miles a year for the past 20 years, or
another way to put it might be that together they have ridden from 20
- 30 thousand miles a year for the past 20 years.

Somehow I suspect that they may have encountered rain in that period.


And grandpa has driven his cars without safety belts yet survived ...

For people who do not shy away from unpaved roads or use a lot of
singletrack and ride in the rain there is a much more extreme issue: Wet
mud. You may have never encountered it but I have many times. You reach
in and, after a second or two of nothing, the rim brakes come on but let
off an awful grinding noise. You can literally hear the rim being
tortured but because of a rapidly approaching curve you can't let go. As
I have mentioned before the rims on my old MTB are only 1000mi old but
the front rim is almost shot from all that. Deep grooves.

I stand by my opinion that rim brakes are fair weather brakes. Then they
are fine but not when the going gets tough. Like this kind of weather:

https://www.youtube.com/watch?v=mX_EKybzK4Y


I might comment that I've ridden coaster brakes, drum brakes, rod pull
brakes, cantilever brakes, side pull single pivot caliper brakes,
double pivot caliper, Vee brakes and for one short ride a cable disc
brake. and at the time I rode them I found all the brakes to give
acceptable service. Well with one exception, rim brakes and chrome
plated steel rims were sometimes a bit iffy :-)


Yes, those were the worst. It got a little better with aluminum rims but
not a lot. In the world of automotive such a brake "system" would not
stand the slightest change of being legal.

Finally after many decades the bicycle industry woke up and adopted what
the automotive guys had all along, disc brakes. Why should I accept an
inferior brake system on a new bike when there is a much better one?

Well, when I worked on airplanes I remember that the F-4 had multi
plate disc brakes which provided a tremendous amount of stopping power
in a very small package.


Some tandems have that as well, and of course motorcycles: Two discs up
front. But not stacks of discs.


One supposes that will be next big improvement in bicycle brakes. Or
perhaps a drag chute for those long downhill's to keep the rims from
melting?


I've thought about it :-)

--
Regards, Joerg

http://www.analogconsultants.com/

Oh ****! I've ridden many hundreds of miles off road in dry and wet sand, mud, heavy rain, rutted roads/trails and did so on an MTB with cantilever brakes and NEVER had trouble stopping either when I needed to or when I wanted too. I've ridden on ice and in 4 inches+ deep snowand also never had trouble stopping.

Perhaps you ride too fast for the conditions/sight lines or you don't keep your brakes adjusted properly.

Really? I have trouble standing up on ice. There is a point at which you don't want super-strong brakes.

-- Jay Beattie.


Yeah me too.
Snow is one thing - I'm used to that- but ice is quite
another. Depending on the recent weather, a frozen slick
patch of ice under snow will dump me right on my ass. We
mere humans would have some trouble with Jobst's famous tour
down a frozen Swiss river.

I've never ridden a bicycle on ice or snow but wouldn't studded tires
serve? Either
http://www.peterwhitecycles.com/studdedtires.php
or for severe conditions
https://www.youtube.com/watch?v=sQ4kufaQ-lg

I've done a lot of riding in snow, but mostly when I was much younger.
(Well, I was almost always much younger...) I still do it occasionally.

Fresh snow isn't much problem at all. One has to take things slow,
especially cornering and braking. But I almost never do it in
significant traffic. And re-frozen slush is almost impossible.

One very avid bike commuter in our club showed up with a broken bone
last year. His studded tires got him all the way from work to his
driveway, but the bump where his driveway met the street sent him down hard.


--
- Frank Krygowski

Why do some forks and frames have brake rotor size limits?
 

On Sun, 29 Oct 2017 01:45:50 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 15:12:37 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 06:23:59 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 03:54:43 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

I'm not sure that is correct. After all some old Greek guy was
supposed to have said, "Give me a lever and a place to stand and I
will move the earth". Nothing about being close.

No. I'm pretty certain I'm right here. Let's say that you can pull 100 lbs
on your brake lever and the lever has 2" of play before it hits your bars.
You can fiddle with leverage many places in the system, but the product of
that initial 100 lbs and 2" will be constant in the system. If the final
travel of the brake pads is 1/2", then you can apply 400 lbs force to the
pads. If you tighten up your tolerances such that the pads only have to
move 1/16", then you can increase the leverage to the point where you can
apply 3200 lbs force to the pads. In disk brake systems this reduction in
pad-disk distance allow the MA to be increased to compensate for the
decreased leverage of the disk on the wheel. The increases brake pad
pressure at a given bike deceleration is what gives disk brakes more
consistent performance in the wet.

Movement of the parts doesn't make any difference the efficiency is
the pressure applied to the brake lever versus the pressure applied to
the braking device, usually the pads themselves.

A lever that is 1 foot long and moves, lets say, one quarter of the
diameter of a 2 foot circle applies the same force to a load located 1
foot from the fulcrum as a 100 ft lever which moves 1/4 of the
diameter of a 200 ft circle applies to a load that is 100 ft. from the
fulcrum. The first lever moves 19 inches and the second moves 157
feet.

Sure. But the distance you can move your brake lever is limited by the
length of your fingers, and so the distance you can move at the lever end
is essentially fixed. To increase the mechanical advantage in THAT system,
you have to reduce the distance the brake pads move. No ifs, ands, buts or
maybes.

You are talking about two different things. Mechanical efficiency and
how long your fingers are.

They aren't really related.
--
Cheers,

John B.

Theoretically, the mechanical advantage of a brake system and the length of
your fingers aren't related, but practically, in this example of the
mechanical advantage of a bicycle brake system, the two quantities are
chained together at the ankles. You can't have high brake pad travel and
high mechanical advantage unless the travel of the brake lever is very
large, and human hand dimensions just won't allow that.

Well you can continue to equate mechanical advantage with long, or
short, fingers but it doesn't make it true :-)

But you keep talking about the large clearance between the rim brake
pads and the rim versus the disc pads and the disc which isn't
necessarily true.

I use brifters - Shimano STI brake&shifters - on two of my bikes and
considering the rather limited travel of the brake levers the pads
need to be fitted very closely to the rims, and of course, the rims
need to be very straight. The two bikes are about 1,000 km from where
I'm presently located so I'm going much by memory but I think that the
pad to rim clearance is about 1mm. The two bikes I have here both have
down tube shifting and the brake pad clearance is largely determined
by where I want the brake levers to be when the brakes are applied,
but measuring one bike shows that the clearance is about 6mm.

I can sense no appreciable difference in the pressure I feel against
my fingers when stopping any of the four bikes.
--
Cheers,

John B.

I think we're pretty close to a standoff here, so I'll invoke the name of
Sheldon, and then give up. Read through

https://www.sheldonbrown.com/cantilever-geometry.html

and tell me if it changes your opinion about what I've been saying.

To summarize my position
1) The mechanical advantage of a brake system (ie: the ratio of pad force
to lever force) is the inverse of the ratio of pad travel to lever travel.

2) bike brakes are made for humans and not orangutans or aliens, so they
all tend to have about the same amount of lever travel.

3) because of 1 and 2, the travel of the brake pad is pretty much inversely
proportional to the mechanical advantage.

4) because of 1, 2 and the fact that brakes need to actually touch the
rim/disk in order to work, the mechanical advantage of a bicycle brake
system is approximately inversely proportional to how far you can set the
pads away from the rim/disk and still have the system work (non-linear
systems excepted).

If you still doubt what I say, you may have to continue the discussion with
somebody else, as I have obviously failed in my attempts to communicate.


Yes, Sheldon says just what I've been saying that mechanical advantage
is the relationship between force in and force out and he describes
it, as I did, two ways. One as a ratio of forces and two a ratio of
distances. i.e., a lever that has a ratio of two to one will exert
twice the force on the shorter end as applied to the longer end and by
the same token that the long end will travel twice as far as the short
end.

It has nothing to do with finger length or brake pad clearance.
--
Cheers,

John B.