Discs

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?

On Thu, 16 Nov 2017 07:47:19 +0100, 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?

https://www.ebay.com/sch/Honda-Motor...i.html?_fsrp=1
https://www.boschautoparts.com/en/au...c-brake-rotors
http://www.aerobrake.com/?gclid=EAIa... AEgLxKfD_BwE
--
Cheers,

John B.

On Thursday, November 16, 2017 at 7:47:23 AM UTC+1, 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 is my guess.

Lou

wrote in message
...
On Thursday, November 16, 2017 at 7:47:23 AM UTC+1, 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 is my guess.

Sometimes its about water clearance, but probably a "two birds with one
stone" kind of thing.

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?

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

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

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.Â* Why do bicycle discs have them?

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?

Ned

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?

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?

Ned

The thinner, the lighter. Thicker discs do not cool worse as heat
dissipated is the same as the surface area.
And replacement rate goes up.

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/

On Thursday, November 16, 2017 at 6:43:23 AM UTC-7, 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?

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

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

when there's a brake tug on the front end ...hearing is at aloss with closed windows ...then the brake is inspected with an LED thru slots in the disc...check with Goo Images

I cured one-two with a direct spraying at the car wash..last removing a tick tick not herd thru a closed ac window pass side... accidently pulled into the pressure manure wagon spray hold

when in doubt get down turn wheels spray both sides .. same for bike ? spray first ask later

On Friday, November 17, 2017 at 12:42:42 PM UTC-7, wrote:
On Thursday, November 16, 2017 at 6:43:23 AM UTC-7, 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?

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

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

when there's a brake tug on the front end ...hearing is at aloss with closed windows ...then the brake is inspected with an LED thru slots in the disc...check with Goo Images

I cured one-two with a direct spraying at the car wash..last removing a tick tick not herd thru a closed ac window pass side... accidently pulled into the pressure manure wagon spray hold

when in doubt get down turn wheels spray both sides .. same for bike ? spray first ask later

goo.gl/j6Dzkj

the xtreme wavy cut has my curiosity but not found here. saw it hard to track a circle on that.