#11
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Discs
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
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Discs
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
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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
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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
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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
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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
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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
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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
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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
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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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