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  #11  
Old November 16th 17, 10:21 PM posted to rec.bicycles.tech
Tosspot[_3_]
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Posts: 1,096
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On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.


Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.

[1] In deference to John B.
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  #12  
Old November 17th 17, 12:24 AM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 4,699
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On 2017-11-16 09:24, Ned Mantei wrote:
On 16-11-17 14:43, AMuzi wrote:
On 11/16/2017 12:47 AM, Tosspot wrote:
Why do they have holes in them?

Car discs don't, motorbike discs don't, aircraft discs
don't. Why do bicycle discs have them?



Weight and also for swiping dirt and stuff. However, larger holes carry
a risk if you ride too close to another guy on a trail with finer
decomposed granite (we have a lot of that stuff). If a granule flies
into a rotor slot of the front wheel that can make for an "interesting
event".

Another downside of holes is the accumulation of "brake mousse" when you
ride through dense vegetation. It cakes up in there and then bakes. In
our area with yellow star-thistle and all that it can also stink. But
nothing that a Swiss Army knife can't fix. Just don't use it for cutting
sausage afterwards.


Many do have slots or holes. Typical low-end auto discs have a center
air channel. Our researcher discovered this by completely ignoring
normal maintenance:

http://www.yellowjersey.org/photosfr...t/NRCTDISC.JPG


As a maybe related question: Why do bike discs allow for so little wear?
The Shimano Ice-Tech discs are 1.8 mm thick, and need to replaced when
they wear to 1.5 mm. Would there be an issue with cooling if they were
thicker? Or, in the worst case, is this just a way for Shimano to sell
more replacements?


Buy rotors that are at least 1.9mm or thicker. On an MTB they last
around 5000 miles depending on turf, probably much longer on road bikes.
My first ones were 2.2mm and lasted even longer but couldn't find any
last month. It is also important to buy the better ones and not the
"resin pad only" rotors.

I sure wish they were 3mm or more.

--
Regards, Joerg

http://www.analogconsultants.com/
  #13  
Old November 17th 17, 12:28 AM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 4,699
Default Discs

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.


Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


[1] In deference to John B.



--
Regards, Joerg

http://www.analogconsultants.com/
  #14  
Old November 17th 17, 12:56 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 3,641
Default Discs

On Thu, 16 Nov 2017 19:17:22 -0000, "Ian Field"
wrote:



"Tosspot" wrote in message
m...
Why do they have holes in them?

Car discs don't, motorbike discs don't, aircraft discs don't. Why do
bicycle discs have them?


Damn - I was just seeking crowd funding for a start up in motorcycle disc
locks.

Vaguely remember seeing a car disc with holes - but can't remember where.

its to a considerable extent, a trendy thing, and not many aircraft cruise
past the girlies on the high street. Aircraft probably use cast iron discs
because it works better and is lighter than stainless - and cast iron might
be too brittle to make loads of holes in it.


Most aircraft use multiple disks
http://tinyurl.com/y7c5qb55
--
Cheers,

John B.

  #15  
Old November 17th 17, 01:09 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 3,641
Default Discs

On Thu, 16 Nov 2017 15:28:13 -0800, Joerg
wrote:

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.


Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


https://www.amazon.com/SRAM-Guide-Ul.../dp/B00XAY7CYK
or
http://www.jensonusa.com/SRAM-Guide-...te-Disc-Brake/
The SRAM brake Ultimate Brake with 950mm front discs and 1,800 rear
discs.

I assume these are for the "go fast people".
--
Cheers,

John B.

  #16  
Old November 17th 17, 01:23 AM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 4,699
Default Discs

On 2017-11-16 16:09, John B. wrote:
On Thu, 16 Nov 2017 15:28:13 -0800, Joerg
wrote:

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.

Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


https://www.amazon.com/SRAM-Guide-Ul.../dp/B00XAY7CYK
or
http://www.jensonusa.com/SRAM-Guide-...te-Disc-Brake/
The SRAM brake Ultimate Brake with 950mm front discs and 1,800 rear
discs.


Quote "ROTOR SIZES: 140, 160, 170, 180, 200mm"

I've got that already. It's not solid rotors.


I assume these are for the "go fast people".



What's so special about this stuff other than very high prices?

--
Regards, Joerg

http://www.analogconsultants.com/
  #17  
Old November 17th 17, 01:36 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 9,068
Default Discs

On 11/16/2017 6:09 PM, John B. wrote:
On Thu, 16 Nov 2017 15:28:13 -0800, Joerg
wrote:

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.

Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


https://www.amazon.com/SRAM-Guide-Ul.../dp/B00XAY7CYK
or
http://www.jensonusa.com/SRAM-Guide-...te-Disc-Brake/
The SRAM brake Ultimate Brake with 950mm front discs and 1,800 rear
discs.

I assume these are for the "go fast people".


Or at least "stop fast people".
Note: rotor not included.
Also, I believe 950mm and 180mm are hydraulic tube lengths.
Rotors that large would not clear any standard bicycle wheel!

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #18  
Old November 17th 17, 02:03 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 3,641
Default Discs

On Thu, 16 Nov 2017 18:36:04 -0600, AMuzi wrote:

On 11/16/2017 6:09 PM, John B. wrote:
On Thu, 16 Nov 2017 15:28:13 -0800, Joerg
wrote:

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.

Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


https://www.amazon.com/SRAM-Guide-Ul.../dp/B00XAY7CYK
or
http://www.jensonusa.com/SRAM-Guide-...te-Disc-Brake/
The SRAM brake Ultimate Brake with 950mm front discs and 1,800 rear
discs.

I assume these are for the "go fast people".


Or at least "stop fast people".
Note: rotor not included.
Also, I believe 950mm and 180mm are hydraulic tube lengths.
Rotors that large would not clear any standard bicycle wheel!


Yup. I read the SRAM site and the maximum rotor size seems to be
200mm.
--
Cheers,

John B.

  #19  
Old November 17th 17, 02:05 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 3,641
Default Discs

On Thu, 16 Nov 2017 16:23:34 -0800, Joerg
wrote:

On 2017-11-16 16:09, John B. wrote:
On Thu, 16 Nov 2017 15:28:13 -0800, Joerg
wrote:

On 2017-11-16 13:21, Tosspot wrote:
On 16/11/17 20:38, David Scheidt wrote:
Tosspot wrote:
:Why do they have holes in them?

:Car discs don't, motorbike discs don't, aircraft discs don't. Why do
:bicycle discs have them?

Lots of high-performance car brake rotors are drilled or slotted.
Slotting is more common on better stuff, holes can crack. They serve
a couple of features. One, people think they're cool. two, they
allow the gasses that come off brake pads somewhere to go (this is a
non-issue with modern pads, but it was a problem in the dark ages).
Three, they give water somewhere to go. Four, they improve cooling
(increase surface area). five, the clean pads, and reduce wear.

Gasses off a bicycle pad? Really?

Nobody drills rims, and most[1] motorbikes, which are exposed to the
rain don't.

Because 75 kg of me at 30 kph is the same KE as 160 kph Audi at 1.5
tonnes? Nah.

Hmmm...could it be it helps to clean them? They aren't dissipating the
KE, so they don't get Eeek! hot. But surely the crud would build up in
the holes?

I'm going to order a solid one for the front and fit it in the spring
and see if it makes any difference.


If you find a place (in the US or China) that sells solid 8" or 203mm
rotors please let us know.


https://www.amazon.com/SRAM-Guide-Ul.../dp/B00XAY7CYK
or
http://www.jensonusa.com/SRAM-Guide-...te-Disc-Brake/
The SRAM brake Ultimate Brake with 950mm front discs and 1,800 rear
discs.


Quote "ROTOR SIZES: 140, 160, 170, 180, 200mm"

I've got that already. It's not solid rotors.


I assume these are for the "go fast people".



What's so special about this stuff other than very high prices?


Good Lord! It is made by SRAM and everyone knows that they build super
stuff. Some of which is even used on TdeF racing bicycles :-)

--
Cheers,

John B.

  #20  
Old November 17th 17, 07:00 AM posted to rec.bicycles.tech
Tosspot[_3_]
external usenet poster
 
Posts: 1,096
Default Discs

On 17/11/17 00:56, John B. wrote:
On Thu, 16 Nov 2017 19:17:22 -0000, "Ian Field"
wrote:



"Tosspot" wrote in message
...
Why do they have holes in them?

Car discs don't, motorbike discs don't, aircraft discs don't. Why do
bicycle discs have them?


Damn - I was just seeking crowd funding for a start up in motorcycle disc
locks.

Vaguely remember seeing a car disc with holes - but can't remember where.

its to a considerable extent, a trendy thing, and not many aircraft cruise
past the girlies on the high street. Aircraft probably use cast iron discs
because it works better and is lighter than stainless - and cast iron might
be too brittle to make loads of holes in it.


Most aircraft use multiple disks
http://tinyurl.com/y7c5qb55


They ain't made of drillium though. Mind you

https://www.youtube.com/watch?v=lUMuOyMTQ8Y

Perhaps they should be. Stairs! Bring the ****ing stairs!!!

 




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