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

On 2017-10-30 13:17, Doug Landau wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote:
On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote:
On 2017-10-29 09:45, wrote:
On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote:

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.

There is NO brake the is proof against wet mud. In fact it is perhaps
worse on a disk since the additional pressure of the pads can turn
the silicon present in most muds into cutting instruments that on rim
brakes cuts into the rubber show rather than the hard and thin disk
pad.


Actually, no. I've had mud literally dripping from the calipers which
had become barely recognizable brownish blobs. The only thing that
happens is that they make an awful grinding noise just like muddy rim
brakes do. With the two major differences that they still come on full
force immediately and that this grinding does not eat up aluminum.
Aluminum as one of the braking surfaces plain does not make any sense,
certainly not in a muddy environment.

A downside of bicycle disc brakes is that in contrast to most motor
vehicles the rotors have "vent holes" and weight weenie spiders. This
results in rather fast heat-up and in "brake mousse" when you plow
through thick vegetation on an overgrown trail. Mashed star-thistle and
other weeds get shredded and a sort of pulp develops which cakes up in
the holes of the rotor. It doesn't diminish the brake force but lets of
a bad stench. One of the reasons why I carry a Swiss Army knife in a
pocket. Not in a pannier, so I can whip it out in seconds. This also
helps in poking out the giant mud clump that forms behind the BB and can
prevent the rear wheel from turning.

Joerg - that additional noise is wear.


Sure. However, the rotors last thousands of miles, cost around $20 and
take only minutes to change. The pads cost $2/pair for ceramic-based
material (like motorcycles have) and last around 1000mi depending on
turf and weather. That is way more hassle than with a motor vehicle but
way less hassle than swapping out a shot rim.

I started riding again in fall 2013, using an older model MTB with
almost zero miles on it. By the end of 2013 it had around 1000mi on it
and the front rim looks horrible.

The problem in our area is this: Mud contains granules of decomposed
granite. Rubber pads need water diverter grooves and the granules lodge
in these grooves. They also pierce the rubber itself and lodge in there.
When pulling the lever that lets of a horrid grinding noise. Coming down
a hill you have to keep the brake engaged and you can literally hear the
rim being tortured all the way to the bottom of the hill. On flat
surfaces you have to stop and pry out the granules. On a rainy day that
means stopping every few miles. I stand by my opinion that rim brakes
are inadequate for any serious MTB riding.

That is the reason to use Kool-stop Salmons. The compound will not let granules lodge.


So then why does it on my road bike? I use Koolstop up front, black and
salmon. Gravel flakes embed in both when I travel gravel roads or
unpaved sections during soggy weather. Plus they have grooves which is
where they mostly embed:

http://sheldonbrown.com/harris/images/brk14.jpg

--
Regards, Joerg

http://www.analogconsultants.com/

On Monday, October 30, 2017 at 1:58:51 PM UTC-7, Joerg wrote:
On 2017-10-30 13:17, Doug Landau wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote:
On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote:
On 2017-10-29 09:45, wrote:
On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote:

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.

There is NO brake the is proof against wet mud. In fact it is perhaps
worse on a disk since the additional pressure of the pads can turn
the silicon present in most muds into cutting instruments that on rim
brakes cuts into the rubber show rather than the hard and thin disk
pad.


Actually, no. I've had mud literally dripping from the calipers which
had become barely recognizable brownish blobs. The only thing that
happens is that they make an awful grinding noise just like muddy rim
brakes do. With the two major differences that they still come on full
force immediately and that this grinding does not eat up aluminum.
Aluminum as one of the braking surfaces plain does not make any sense,
certainly not in a muddy environment.

A downside of bicycle disc brakes is that in contrast to most motor
vehicles the rotors have "vent holes" and weight weenie spiders. This
results in rather fast heat-up and in "brake mousse" when you plow
through thick vegetation on an overgrown trail. Mashed star-thistle and
other weeds get shredded and a sort of pulp develops which cakes up in
the holes of the rotor. It doesn't diminish the brake force but lets of
a bad stench. One of the reasons why I carry a Swiss Army knife in a
pocket. Not in a pannier, so I can whip it out in seconds. This also
helps in poking out the giant mud clump that forms behind the BB and can
prevent the rear wheel from turning.

Joerg - that additional noise is wear.


Sure. However, the rotors last thousands of miles, cost around $20 and
take only minutes to change. The pads cost $2/pair for ceramic-based
material (like motorcycles have) and last around 1000mi depending on
turf and weather. That is way more hassle than with a motor vehicle but
way less hassle than swapping out a shot rim.

I started riding again in fall 2013, using an older model MTB with
almost zero miles on it. By the end of 2013 it had around 1000mi on it
and the front rim looks horrible.

The problem in our area is this: Mud contains granules of decomposed
granite. Rubber pads need water diverter grooves and the granules lodge
in these grooves. They also pierce the rubber itself and lodge in there.
When pulling the lever that lets of a horrid grinding noise. Coming down
a hill you have to keep the brake engaged and you can literally hear the
rim being tortured all the way to the bottom of the hill. On flat
surfaces you have to stop and pry out the granules. On a rainy day that
means stopping every few miles. I stand by my opinion that rim brakes
are inadequate for any serious MTB riding.

That is the reason to use Kool-stop Salmons. The compound will not let granules lodge.


So then why does it on my road bike? I use Koolstop up front, black and
salmon. Gravel flakes embed in both when I travel gravel roads or
unpaved sections during soggy weather. Plus they have grooves which is
where they mostly embed:

http://sheldonbrown.com/harris/images/brk14.jpg

--
Regards, Joerg

http://www.analogconsultants.com/

Take a pic next time until then we don't believe it

On Monday, October 30, 2017 at 1:48:30 PM UTC-7, Joerg wrote:
On 2017-10-30 12:44, wrote:
On Monday, October 30, 2017 at 9:51:06 AM UTC-7, Joerg wrote:

I worked in med-tech for a long time and so far all docs are of
opposite opinion.

Yes, some benefits of helmets will be offset by increase sisk
taking. Also, there were no Kawasaki Ninjas and such before the
helmet law.

I know and that is why it is dangerous to listen to doctors.

http://www.vehicularcyclist.com/kunich.html


With all due respect, quote

"... that no area receives more than a single blow. While it is plain
why this is done, it most assuredly does not mimic the real world where
a person falling off a bicycle may have his head bounce down the road
several times before stopping ..."

doesn't apply to many serious accidents. Most that I know of were one
big smack into something hard. A tree, a rock, a car. You might roll off
and hit something else or the pavement but not at full brunt anymore.
Others have had such crashes where they came away alright but the
styrofoam inside the helmet had clearly absorbed a lot of the impact
energy and was crushed. That's when the helmet must be replaced.

This is why you find styrofoam in or behind the bumber of many cars.


There is no change since 2002 because the only way of improving a
helmet is via increasing the size. And helmets are already of
bothersome size to people.

Remember that I was the safety director of the American Federation of
Motorcyclists after I gave up racing. I was also a professional
mechanic with the American Motorcycle Association.

So when I speak about helmets it is from a position of study as well
as painful experience.


Ok, everybody has their opinion. The docs I spoke to were very much
convinced of the benefits of helmets. Some accidents remained the same
in terms of force despite advances in motorcycle engines. For example in
cities where traffic is slow it doesn't matter much whether you ride a
Ninja or a 250.

What if you ride a Ninja 250?
https://www.google.com/search?q=ninj...w=1322&bih=672


That's one area where they saw a noticable drop in the
severity of head injuries.

Ninja 250 riders have less-severe head injuries?

On 2017-10-30 14:04, Doug Landau wrote:
On Monday, October 30, 2017 at 1:58:51 PM UTC-7, Joerg wrote:
On 2017-10-30 13:17, Doug Landau wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote:
On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote:
On 2017-10-29 09:45, wrote:
On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote:

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.

There is NO brake the is proof against wet mud. In fact it is perhaps
worse on a disk since the additional pressure of the pads can turn
the silicon present in most muds into cutting instruments that on rim
brakes cuts into the rubber show rather than the hard and thin disk
pad.


Actually, no. I've had mud literally dripping from the calipers which
had become barely recognizable brownish blobs. The only thing that
happens is that they make an awful grinding noise just like muddy rim
brakes do. With the two major differences that they still come on full
force immediately and that this grinding does not eat up aluminum.
Aluminum as one of the braking surfaces plain does not make any sense,
certainly not in a muddy environment.

A downside of bicycle disc brakes is that in contrast to most motor
vehicles the rotors have "vent holes" and weight weenie spiders. This
results in rather fast heat-up and in "brake mousse" when you plow
through thick vegetation on an overgrown trail. Mashed star-thistle and
other weeds get shredded and a sort of pulp develops which cakes up in
the holes of the rotor. It doesn't diminish the brake force but lets of
a bad stench. One of the reasons why I carry a Swiss Army knife in a
pocket. Not in a pannier, so I can whip it out in seconds. This also
helps in poking out the giant mud clump that forms behind the BB and can
prevent the rear wheel from turning.

Joerg - that additional noise is wear.


Sure. However, the rotors last thousands of miles, cost around $20 and
take only minutes to change. The pads cost $2/pair for ceramic-based
material (like motorcycles have) and last around 1000mi depending on
turf and weather. That is way more hassle than with a motor vehicle but
way less hassle than swapping out a shot rim.

I started riding again in fall 2013, using an older model MTB with
almost zero miles on it. By the end of 2013 it had around 1000mi on it
and the front rim looks horrible.

The problem in our area is this: Mud contains granules of decomposed
granite. Rubber pads need water diverter grooves and the granules lodge
in these grooves. They also pierce the rubber itself and lodge in there.
When pulling the lever that lets of a horrid grinding noise. Coming down
a hill you have to keep the brake engaged and you can literally hear the
rim being tortured all the way to the bottom of the hill. On flat
surfaces you have to stop and pry out the granules. On a rainy day that
means stopping every few miles. I stand by my opinion that rim brakes
are inadequate for any serious MTB riding.

That is the reason to use Kool-stop Salmons. The compound will not let granules lodge.


So then why does it on my road bike? I use Koolstop up front, black and
salmon. Gravel flakes embed in both when I travel gravel roads or
unpaved sections during soggy weather. Plus they have grooves which is
where they mostly embed:

http://sheldonbrown.com/harris/images/brk14.jpg

--
Regards, Joerg

http://www.analogconsultants.com/

Take a pic next time until then we don't believe it


We? Are you now spokesman for the whole NG? Was there a party convention
with flags and brass band that I missed?

As I said I no longer use rim brakes on my MTB. I do on the road bike
(and only because it can't take disc brake calipers) but soggy days are
still far away and I usually don't carry a camera. My cell phone is a
Nokia 2115i which was introduced shortly after the Flintstone's rock
car, has no camera.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-10-30 14:06, Doug Landau wrote:
On Monday, October 30, 2017 at 1:48:30 PM UTC-7, Joerg wrote:
On 2017-10-30 12:44, wrote:
On Monday, October 30, 2017 at 9:51:06 AM UTC-7, Joerg wrote:

I worked in med-tech for a long time and so far all docs are of
opposite opinion.

Yes, some benefits of helmets will be offset by increase sisk
taking. Also, there were no Kawasaki Ninjas and such before the
helmet law.

I know and that is why it is dangerous to listen to doctors.

http://www.vehicularcyclist.com/kunich.html


With all due respect, quote

"... that no area receives more than a single blow. While it is plain
why this is done, it most assuredly does not mimic the real world where
a person falling off a bicycle may have his head bounce down the road
several times before stopping ..."

doesn't apply to many serious accidents. Most that I know of were one
big smack into something hard. A tree, a rock, a car. You might roll off
and hit something else or the pavement but not at full brunt anymore.
Others have had such crashes where they came away alright but the
styrofoam inside the helmet had clearly absorbed a lot of the impact
energy and was crushed. That's when the helmet must be replaced.

This is why you find styrofoam in or behind the bumber of many cars.


There is no change since 2002 because the only way of improving a
helmet is via increasing the size. And helmets are already of
bothersome size to people.

Remember that I was the safety director of the American Federation of
Motorcyclists after I gave up racing. I was also a professional
mechanic with the American Motorcycle Association.

So when I speak about helmets it is from a position of study as well
as painful experience.


Ok, everybody has their opinion. The docs I spoke to were very much
convinced of the benefits of helmets. Some accidents remained the same
in terms of force despite advances in motorcycle engines. For example in
cities where traffic is slow it doesn't matter much whether you ride a
Ninja or a 250.

What if you ride a Ninja 250?
https://www.google.com/search?q=ninj...w=1322&bih=672


That's one area where they saw a noticable drop in the
severity of head injuries.

Ninja 250 riders have less-severe head injuries?


I meant this kind of 250:

https://upload.wikimedia.org/wikiped...c/cd/Maico.jpg

--
Regards, Joerg

http://www.analogconsultants.com/

On Monday, October 30, 2017 at 1:54:27 PM UTC-7, Joerg wrote:

snip

Well, perhaps it was from older parts but I saw a significant number
of MTB riders walking their bikes back off of hills. Those were the
older cable pull brakes so that might have been when they were still
developing the proper compounds.

https://www.youtube.com/watch?v=Wdb7KEc7xJI


Wow, 2x the stopping distance for the rim brakes. I wouldn't have
imagined it could be that much worse.


This is comparing an 11 speed Ghost with an aluminum el-cheapo
Raleigh. This was a highly unfair test to begin with: On the climbing
test the Raleigh had an eight speed compact that simply didn't have
the correct gearing. And the bicycle size and set-up was entirely
wrong.

On the braking test it was hydraulic disks against what appeared to
the the old-fashioned long throw brakes. There was so much bend in
the brakes that you could bottom out the lever.


I don't think he bottomed out the levers.


On the TT again the problem was that there simply wasn't the proper
gearing. And since the Raleigh wasn't sized correctly it was nearly
impossible to get into an aero position.

Personally in the brake test I believe my Skeleton brakes would have
finished not exactly with the disks but really close. There is no
flex to speak of in my brakes and while I think I could lock the
front wheel and allow the rear wheel to rise off of the ground there
is absolutely no day I would do such a thing.

My bikes are set up similar seating position to the Raleigh. But I
could merely change the stem to gain a position such as the Ghost. I
personally don't give much credit to the aerodynamics of a frame.


Gearing and such are a different matter but brakes are safety-relevant.
I wouldn't want to compromise there.

I don't know about TK's skeleton brakes, but a pair of Ultegra level dual pivots stop just as a well as a front disc in dry conditions, and any difference in stopping power is eclipsed by traction loss or other safety issues, like losing front-end or rear-end control. As for rear power, a disc is stronger than a dual pivot because of cable stretch, but it is not necessarily a good thing. A rear hydraulic disc can be too powerful for a novice user. I've fish-tailed a half dozen times on my discs, mostly while getting used to the increased braking power but once recently with a well-weighted panic stop. Braking distance also depends on rider skill, experience and nerves.

Having ridden discs in dry and wet this weekend (waiting for my replacement racing bike with ordinary rim brakes), discs were un-spectacular on Saturday (dry) and were in fact annoying because of screeching, and on Sunday (wet muddy gravel ride), they were great and were actually less screechy, no rim grinding and really stopped well. I continue to give discs a thumbs-up for wet weather riding. With that said, on Sunday I was riding with a guy on a CX bike with cantis, and he seemed to be doing fine. The only brake issue were experienced by my BCF (best cycling friend) who was using TRP cable discs. He had to stop and adjust them. You have to be mindful of cable discs. The brakes work great when properly adjusted.

-- Jay Beattie.

On 2017-10-29 09:13, wrote:
On Friday, October 27, 2017 at 6:13:58 PM UTC-7, 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.

2) The disk is not connected to the rim, so it doesn't bend and
warp when you hit a pothole. Again, the pads can sit closer and
have higher MA.

3) The disk doesn't thermally couple to the tire, so no blowouts on
long descents.

4) The disk is solid, so there's less flexing when you squeeze it
with the pads.

1) there is no such thing as a 622 mm disk. And there would be
insufficient fork clearance on any bike including cross bikes.

2) While the disk is not attached to the rim what gives you the idea
that the spokes stretch or bend? Especially modern wheels are
virtually a rigid structure.


With bike disc brakes? They do stretch, big time. When I brake really
hard on the MTB, shift down and then muscle up a hill you can hear the
spokes going KENG, KEINGGG, POCK, TO-TO-TOCK. Probably comes from the
points where they cross.


3) And you can see disks distort when one pad wears out which is
pretty rapidly.


One pad? That can only happen on mechanical disc brakes which are
designed cheaply. Hydraulic disc brakes have calipers with two or four
pistons, not just one. In automotive there are older ones with just one
but then the whole caliper floats on sideways rails.


... Deep grooves are worn into the disk pretty rapidly in
these cases. There is simply insufficient room for a deep enough pad
to get reasonable wear characteristics.


Mine wear almost perfectly in a uniform fashion.


4) The disks aren't solid anymore. They are drilled and grooved and
the inside diameter is reduced to the usable minimum. The carriers
are aluminum and it is possible to actually melt the carrier on a
racer.


Most regular rotors don't have aluminum spiders. That that do take a
while for the heat to cross the rivets.


As everything else there are advantages and disadvantages but the
fact remains that almost all of the advantages are over-ridden by the
fact that they are nothing more than marketing.


What, disc brakes are just marketing? My opinon is the complete
opposite. There are stretches of trail I would walk instead of ride if I
didn't have hydraulic disc brakes. They have saved the bacon more than
once. The last incident was a big fat rattlesnake. The MTB came to a
halt 3ft from it. 2ft would probably not have been enough to avoid a
strike and in the boonies without cell coverage that can become a problem.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-10-29 08:58, wrote:
On Friday, October 27, 2017 at 5:48:25 PM UTC-7, 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....

I am somewhat puzzled as well. Off-road and especially with the
rather immense weight of Joerg's full suspension I can understand the
disks since you could bend the rims inwards with the forces you have
to apply to slow on very steep terrain at high speeds. But road
bikes?

Two days ago as I returned home I crossed a patch of concrete and
then grass. I found myself having to pump the skeleton brakes because
they were so powerful they were about to lock the wheels even on the
concrete. Why in heavens name would I need a disk? And why would you
EVER ride on the streets in such a manner that the half second it
takes to clear water from the front of the brake shoe would be the
difference between having an accident and not?


One of many examples, happened to me: A buck came running smack-dab into
my path, from diagonally behind. He clearly must have seen but ignored
me. Without disc brakes we would likely have collided.

--
Regards, Joerg

http://www.analogconsultants.com/

On Monday, October 30, 2017 at 2:16:43 PM UTC-7, Joerg wrote:
On 2017-10-30 14:04, Doug Landau wrote:
On Monday, October 30, 2017 at 1:58:51 PM UTC-7, Joerg wrote:
On 2017-10-30 13:17, Doug Landau wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote:
On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote:
On 2017-10-29 09:45, wrote:
On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote:

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.

There is NO brake the is proof against wet mud. In fact it is perhaps
worse on a disk since the additional pressure of the pads can turn
the silicon present in most muds into cutting instruments that on rim
brakes cuts into the rubber show rather than the hard and thin disk
pad.


Actually, no. I've had mud literally dripping from the calipers which
had become barely recognizable brownish blobs. The only thing that
happens is that they make an awful grinding noise just like muddy rim
brakes do. With the two major differences that they still come on full
force immediately and that this grinding does not eat up aluminum.
Aluminum as one of the braking surfaces plain does not make any sense,
certainly not in a muddy environment.

A downside of bicycle disc brakes is that in contrast to most motor
vehicles the rotors have "vent holes" and weight weenie spiders. This
results in rather fast heat-up and in "brake mousse" when you plow
through thick vegetation on an overgrown trail. Mashed star-thistle and
other weeds get shredded and a sort of pulp develops which cakes up in
the holes of the rotor. It doesn't diminish the brake force but lets of
a bad stench. One of the reasons why I carry a Swiss Army knife in a
pocket. Not in a pannier, so I can whip it out in seconds. This also
helps in poking out the giant mud clump that forms behind the BB and can
prevent the rear wheel from turning.

Joerg - that additional noise is wear.


Sure. However, the rotors last thousands of miles, cost around $20 and
take only minutes to change. The pads cost $2/pair for ceramic-based
material (like motorcycles have) and last around 1000mi depending on
turf and weather. That is way more hassle than with a motor vehicle but
way less hassle than swapping out a shot rim.

I started riding again in fall 2013, using an older model MTB with
almost zero miles on it. By the end of 2013 it had around 1000mi on it
and the front rim looks horrible.

The problem in our area is this: Mud contains granules of decomposed
granite. Rubber pads need water diverter grooves and the granules lodge
in these grooves. They also pierce the rubber itself and lodge in there.
When pulling the lever that lets of a horrid grinding noise. Coming down
a hill you have to keep the brake engaged and you can literally hear the
rim being tortured all the way to the bottom of the hill. On flat
surfaces you have to stop and pry out the granules. On a rainy day that
means stopping every few miles. I stand by my opinion that rim brakes
are inadequate for any serious MTB riding.

That is the reason to use Kool-stop Salmons. The compound will not let granules lodge.


So then why does it on my road bike? I use Koolstop up front, black and
salmon. Gravel flakes embed in both when I travel gravel roads or
unpaved sections during soggy weather. Plus they have grooves which is
where they mostly embed:

http://sheldonbrown.com/harris/images/brk14.jpg

--
Regards, Joerg

http://www.analogconsultants.com/

Take a pic next time until then we don't believe it


We? Are you now spokesman for the whole NG? Was there a party convention
with flags and brass band that I missed?

Yes. The election that decided this NG's creation. Now quit yer whining and take the goddam pic. This will be of interest to many here. The salmon koolstops and their resistance to embedding rocks are part of the lore of this group, and salmons are popular out of proportion here. Now quit complaining about a little effort to do your part, and show us pics of granules embedded in your salmon.

On 2017-10-30 15:10, Doug Landau wrote:
On Monday, October 30, 2017 at 2:16:43 PM UTC-7, Joerg wrote:
On 2017-10-30 14:04, Doug Landau wrote:
On Monday, October 30, 2017 at 1:58:51 PM UTC-7, Joerg wrote:
On 2017-10-30 13:17, Doug Landau wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg
wrote:
On 2017-10-29 12:57, wrote:
On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg
wrote:
On 2017-10-29 09:45, wrote:
On Saturday, October 28, 2017 at 8:09:18 AM UTC-7,
Joerg wrote:

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.

There is NO brake the is proof against wet mud. In
fact it is perhaps worse on a disk since the
additional pressure of the pads can turn the silicon
present in most muds into cutting instruments that on
rim brakes cuts into the rubber show rather than the
hard and thin disk pad.


Actually, no. I've had mud literally dripping from the
calipers which had become barely recognizable brownish
blobs. The only thing that happens is that they make an
awful grinding noise just like muddy rim brakes do.
With the two major differences that they still come on
full force immediately and that this grinding does not
eat up aluminum. Aluminum as one of the braking
surfaces plain does not make any sense, certainly not
in a muddy environment.

A downside of bicycle disc brakes is that in contrast
to most motor vehicles the rotors have "vent holes" and
weight weenie spiders. This results in rather fast
heat-up and in "brake mousse" when you plow through
thick vegetation on an overgrown trail. Mashed
star-thistle and other weeds get shredded and a sort of
pulp develops which cakes up in the holes of the rotor.
It doesn't diminish the brake force but lets of a bad
stench. One of the reasons why I carry a Swiss Army
knife in a pocket. Not in a pannier, so I can whip it
out in seconds. This also helps in poking out the giant
mud clump that forms behind the BB and can prevent the
rear wheel from turning.

Joerg - that additional noise is wear.


Sure. However, the rotors last thousands of miles, cost
around $20 and take only minutes to change. The pads cost
$2/pair for ceramic-based material (like motorcycles have)
and last around 1000mi depending on turf and weather. That
is way more hassle than with a motor vehicle but way less
hassle than swapping out a shot rim.

I started riding again in fall 2013, using an older model
MTB with almost zero miles on it. By the end of 2013 it had
around 1000mi on it and the front rim looks horrible.

The problem in our area is this: Mud contains granules of
decomposed granite. Rubber pads need water diverter grooves
and the granules lodge in these grooves. They also pierce
the rubber itself and lodge in there. When pulling the
lever that lets of a horrid grinding noise. Coming down a
hill you have to keep the brake engaged and you can
literally hear the rim being tortured all the way to the
bottom of the hill. On flat surfaces you have to stop and
pry out the granules. On a rainy day that means stopping
every few miles. I stand by my opinion that rim brakes are
inadequate for any serious MTB riding.

That is the reason to use Kool-stop Salmons. The compound
will not let granules lodge.


So then why does it on my road bike? I use Koolstop up front,
black and salmon. Gravel flakes embed in both when I travel
gravel roads or unpaved sections during soggy weather. Plus
they have grooves which is where they mostly embed:

http://sheldonbrown.com/harris/images/brk14.jpg

-- Regards, Joerg

http://www.analogconsultants.com/

Take a pic next time until then we don't believe it


We? Are you now spokesman for the whole NG? Was there a party
convention with flags and brass band that I missed?

Yes. The election that decided this NG's creation.


Ah, a Chinese style coronation :-)


... Now quit yer
whining and take the goddam pic.


Can you tell me how when the weather is bone dry for months?


... This will be of interest to many
here. The salmon koolstops and their resistance to embedding rocks
are part of the lore of this group, and salmons are popular out of
proportion here.


Maybe there are versions with li'l gremlins in the grooves that shovel
all the dirt out that gets in. Mine don't have those gremlins.


... Now quit complaining about a little effort to do
your part, and show us pics of granules embedded in your salmon.


See above. And it better rain hard soon because my black/salmon
Koolstops are very close to worn down and I certainly will not replace
them with new Koolstops. They wanted $17/pair for the MTB version last
time I looked. Not going to happen. IME Clarks work just as well, last
as long and cost only $4/pair.

In terms of grinding after mud exposure I found there was hardly any
difference between Koolstops and Clarks.

--
Regards, Joerg

http://www.analogconsultants.com/