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  1. #101
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    Quote Originally Posted by OO7 View Post
    How much for da' whole plane?
    I don't know, as I bought these from the manufacturer of brakes for the plane.

    I seem to recall something around 100.000.000$ but I may be mistaken


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  2. #102
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    Quote Originally Posted by jpeters View Post
    LOL HA HA thats funny don't forget pics. Wont they break easy if they hit something?
    They are surprisingly strong. i have used this material in the past for performance car brakes, and they turned out to not be fragile at all.

    I would expect them to be quite a bit stronger regarding impact, than steel rotors.

    That will also be enhanced by using a composite carrier.



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  3. #103
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    A pic of the starting point.


    Magura

  4. #104
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    I'd be surprised if that worked at all on a mountain bike. Carbon-carbon brakes require a lot of heat. Formula 1 cars use them but at temperatures of at least 750* F (with optimal temperatures around 1200* F).

    You can also imagine the amount of heat generated by a landing airplane, fighter jet or not…

  5. #105
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    Quote Originally Posted by deadbolt View Post
    I'd be surprised if that worked at all on a mountain bike. Carbon-carbon brakes require a lot of heat. Formula 1 cars use them but at temperatures of at least 750* F (with optimal temperatures around 1200* F).

    You can also imagine the amount of heat generated by a landing airplane, fighter jet or not…
    The need for high temperature for carbon brakes to work, is an old wives tale.

    I have been working with this material previously, as I engineered brakes for performance cars in the past.

    It is true that the last bit of brake power (between 5 and 10% depending on the composite in question), is gained at higher temperatures. However, we are talking surface temperature, so in the event that you need a lot of brake power, the disc will rotate twice, and you have maximum performance.

    1200F (approx. 650C) is however not the optimum working temp., but rather the max. working temp., as oxidation kicks in at around 600C.
    750F (approx. 400C) would be the sweet spot, and not the minimum temp. Again, we are talking surface temp., and even my steel rotors are hitting 300C on a regular ride, judging by the color they get.

    On planes they use an anti oxidation agent, to allow for max. temp. around 800C, but have problems making the anti oxidation agent perform permanently, thus it is re-applied when brakes are maintained.

    Magura

    EDIT: Having said that, I don't know anything about the brakes used in formula 1, but have extensive experience with the type of carbon used for planes and performance cars.

  6. #106
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    Yeah, on the F1 cars they like a minimum of 750* F with a maximum of 1800* F.

    There are high performance sports cars that run them now as well so I'd imagine they're constructed to run at lower temps. That said, that's still a long way from temps generated by a mountain bike.

    I did find a company that makes carbon-carbon road pads, however, the description says they are a "low-temperature" formulation:

    "Zipp worked closely with the leading brake producer for Formula 1 race teams to bring thermally conductive, low-temperature brake pad technology to the bike market..."

    You obviously seem to have some experience with these composites and I only have a basic knowledge from what I've read. It would seem to me a composite designed to work at temperatures of 750* F may not be the best choice for a mountain bike; just sayin'

    Anyway, good luck. I look forward to your impressions/results...

  7. #107
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    Quote Originally Posted by deadbolt View Post
    Yeah, on the F1 cars they like a minimum of 750* F with a maximum of 1800* F.

    There are high performance sports cars that run them now as well so I'd imagine they're constructed to run at lower temps. That said, that's still a long way from temps generated by a mountain bike.

    I did find a company that makes carbon-carbon road pads, however, the description says they are a "low-temperature" formulation:

    "Zipp worked closely with the leading brake producer for Formula 1 race teams to bring thermally conductive, low-temperature brake pad technology to the bike market..."

    You obviously seem to have some experience with these composites and I only have a basic knowledge from what I've read. It would seem to me a composite designed to work at temperatures of 750* F may not be the best choice for a mountain bike; just sayin'

    Anyway, good luck. I look forward to your impressions/results...
    The carbon road pads, are nothing like what Zipp would like to market them as being.
    I base this on the fact that Zipp rims, are a epoxy/carbon composite.
    It is just marketing BS that they try to make it seem they are similar.
    Zipp need to keep things at a much lower temp., for the simple reason that their rims will be damaged by higher temp. Here we are talking like 100C.

    I also am fairly confident that the carbon types used for formula 1 these days, is working in a much wider temp. range. The narrow temp. range is an old wives tale left over from the very beginning of carbon brakes in formula 1.
    Keep in mind that most of the circus you see around formula 1 is entertainment. The real engineering is kept secret.

    There are very many different friction composites out there today, so far I have worked with 3 different types, and none of them had the narrow temp. range that most people seem to think composite brakes suffer from.


    Magura

  8. #108
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    Lmao

    Quote Originally Posted by Mr.Magura View Post
    a small update on the project.

    Recently I got my hands on a brake rotor from a F16 Fighting Falcon.
    They are also made of Carbenix 3000, and guess what, they happen to be 205mm in diameter.

    So next step is to make a spider for it, and machine it down to the right thickness.


    Magura
    Oh my God, dude. Here, the engineers figure out ways to keep the joke rubber dog poop from sticking to th mold. You're taking apart fighter jet parts and finding ways to hack them on to bicycles.

    I love how the mufuggers here on this board are second guessing you, when you are the one with big enough engineer chops to 1) get your hands on Carbenix scraps to mess with and 2) how to fabricate, install and test brake pads made of Carbenix on your bicycle in your spare time. Then, the punchline is they get all pishy with you for saying that if you made them commercially, they would probably be around $150 a set or more. Duh... that's why nobody is going to make them commercially! You never said you would. This is all just fun engineer's experimentation.

    Science is mostly opinion? That dude obviously had no science background... probably believes global warming is a myth.

    2>1... that is not an opinion.

    Ha... All I wanted to do was to add some computer chip heat sinks to a copper plate tucked into a brake caliper to see if it would help keep the pad temps down, and keep heat from sinking into the caliper.

    I made a monster!!

  9. #109
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    Quote Originally Posted by pimpbot View Post
    Science is mostly opinion? That dude obviously had no science background... probably believes global warming is a myth. :

    warming from a greenhouse effect is real, but we are actually set to get colder, as we are entering a record low, low period of the sunspot cycle. Which has much more effect on global temps than the greenhouse effect.

    OFF TOPIC

  10. #110
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    Quote Originally Posted by pimpbot View Post
    Oh my God, dude. Here, the engineers figure out ways to keep the joke rubber dog poop from sticking to th mold. You're taking apart fighter jet parts and finding ways to hack them on to bicycles.

    I love how the mufuggers here on this board are second guessing you, when you are the one with big enough engineer chops to 1) get your hands on Carbenix scraps to mess with and 2) how to fabricate, install and test brake pads made of Carbenix on your bicycle in your spare time. Then, the punchline is they get all pishy with you for saying that if you made them commercially, they would probably be around $150 a set or more. Duh... that's why nobody is going to make them commercially! You never said you would. This is all just fun engineer's experimentation.

    Science is mostly opinion? That dude obviously had no science background... probably believes global warming is a myth.

    2>1... that is not an opinion.

    Ha... All I wanted to do was to add some computer chip heat sinks to a copper plate tucked into a brake caliper to see if it would help keep the pad temps down, and keep heat from sinking into the caliper.

    I made a monster!!

    Ahhh, insanity at last

    On a different note, I just realized that the envelope with the piece of Carbenix I promised you could have, was still not mailed.
    It has been mailed 15 minutes ago.
    Sorry about the delay.

    By the way, we may get a chance to meet up in the beginning of October in SF.


    Magura

  11. #111
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    Quote Originally Posted by Mr.Magura View Post
    A pic of the starting point.


    Magura
    Looks like that rotor is thick enough to slice a few bike-sized rotors out of...

  12. #112
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    How much did you say it would cost for a set of rotors and pads I just may have a guy who would buy it?

  13. #113
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    Quote Originally Posted by jpeters View Post
    How much did you say it would cost for a set of rotors and pads I just may have a guy who would buy it?
    Just the raw material cost for a rotor and a set of pads, will approach 1.400$
    For having it machined, I would guess some 200-300$, but that would require I can find somebody whom are willing and able to do so.
    The composite spider is relatively cheap to make.

    So a set for both front and rear, is double of that.
    For the rear I though fail to see the point of this approach.

    Magura

  14. #114
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    Quote Originally Posted by Mr.Magura View Post
    Just the raw material cost for a rotor and a set of pads, will approach 1.400$
    For having it machined, I would guess some 200-300$, but that would require I can find somebody whom are willing and able to do so.
    The composite spider is relatively cheap to make.

    So a set for both front and rear, is double of that.
    For the rear I though fail to see the point of this approach.

    Magura
    No thanks sorry to waste your time I was thinking less

  15. #115
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    Quote Originally Posted by jpeters View Post
    No thanks sorry to waste your time I was thinking less
    No problem. I didn't expect anybody to be interested in something that expensive, so I just did a rough calc.

    The pads alone are a more digestible 100$ (just machining cost as I have offered to sponsor materials for a few), and I have somebody around willing to machine them.

    Magura

  16. #116
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    Quote Originally Posted by chameleoneel View Post
    warming from a greenhouse effect is real, but we are actually set to get colder, as we are entering a record low, low period of the sunspot cycle. Which has much more effect on global temps than the greenhouse effect.

    OFF TOPIC
    *chuckle*

  17. #117
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    Quote Originally Posted by Mr.Magura View Post
    No problem. I didn't expect anybody to be interested in something that expensive, so I just did a rough calc.

    The pads alone are a more digestible 100$ (just machining cost as I have offered to sponsor materials for a few), and I have somebody around willing to machine them.

    Magura
    So we are talking 70€ or 530 dkk Shipped to Flensburg ? Is that for just one brake or both front and rear?

    PS I know you are not making money its just I have friends who love stuff like this. Including myself

  18. #118
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    Quote Originally Posted by jpeters View Post
    So we are talking 70€ or 530 dkk Shipped to Flensburg ? Is that for just one brake or both front and rear?

    PS I know you are not making money its just I have friends who love stuff like this. Including myself
    The 100$ figure is for pads for one brake.

    Shipping to Flensburg can't be all that expensive, so 30 DKK sounds about right.
    I just sent a piece of Carbenix big enough for a set of pads to California, and that cost me 50 DKK (10$).


    Magura

  19. #119
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    So you need the old pads and the cash and you will send the new ones ?

    Did you ever ride in Apenrade on the mtb trail and I was wondering do you have mtb specific trails out your way? If you do maybe we could take a trip to ride with you.

  20. #120
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    Quote Originally Posted by jpeters View Post
    So you need the old pads and the cash and you will send the new ones ?

    Did you ever ride in Apenrade on the mtb trail and I was wondering do you have mtb specific trails out your way? If you do maybe we could take a trip to ride with you.

    Yes I need a set of pads, and a pic of the caliper. The old pads will not be damaged, as they are just for taking dimensions, and can be returned as well.

    Regarding meeting up, I'm sure open to that, but please let's take that in private.

    If you're situated in the northern part of Germany it would be easy to get together.


    Magura

  21. #121
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    It seems this is gonna happen sooner than expected.
    I just finished machining the rotor after splitting it in two.
    I guess my expectations to how much time it would take to machine it, were a little pessimistic, as they were based on 15" rotors.

    I guess if I don't get held up by something, I will even get around to casting the carbon fiber spider today.

    Magura

  22. #122
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    And as promised, a pic.


    Magura

  23. #123
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    Quote Originally Posted by Mr.Magura View Post
    It seems this is gonna happen sooner than expected.
    I just finished machining the rotor after splitting it in two.
    I guess my expectations to how much time it would take to machine it, were a little pessimistic, as they were based on 15" rotors.

    I guess if I don't get held up by something, I will even get around to casting the carbon fiber spider today.

    Magura
    I am confused Magura you said you will have someone machine the pads for me but you are machining your own rotors? I don't understand do you have a machine shop or are you using a machine shop?

  24. #124
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    Quote Originally Posted by Mr.Magura View Post
    And as promised, a pic.


    Magura

    Nice I wish I had the cash to put some on fighter jet brakes on my bike.

  25. #125
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    Quote Originally Posted by jpeters View Post
    I am confused Magura you said you will have someone machine the pads for me but you are machining your own rotors? I don't understand do you have a machine shop or are you using a machine shop?
    Hmm, the confusion seems understandable

    I have a machine workshop and a lab myself. It is for making work related prototypes.
    I use my own machine workshop for making my own hobby projects as well, as you can see.

    As I have plenty of things to do, I don't make any serial production, and besides that, I don't feel like making my hobby turn into a job, as that would destroy a good spare time entertainment source, and replace it with a low pay job.

    So, I have given a friend of mine a small machine workshop, which is intended to get him off his butt (he got sagged lately), thus having somebody to sort out machining for my real job, and makes me able to sort out machining of a few hobby parts to get me some feedback in exchange.

    So, you're right on both accounts, I have a machine workshop, and I buy from a machine workshop.

    Magura

  26. #126
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    Wow, it's great that you're willing to go to these lengths to test all this out, musy be pretty fun! Hopefully it's things like this which poineer the mainstream brands to push their development further and further.

    Magura, How did you go about splitting your F16 rotor?

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    Quote Originally Posted by joehspicer@msn.com View Post
    Wow, it's great that you're willing to go to these lengths to test all this out, musy be pretty fun! Hopefully it's things like this which poineer the mainstream brands to push their development further and further.

    Magura, How did you go about splitting your F16 rotor?
    It sure is fine entertainment.

    The mainstream brands I would guess, have no particular interest in developing much faster than the competitors, and as you can see previously in this thread, there is a strong opposition to spending that kind of money by the general consumer.
    If we wanted some hefty development in the MTB market, people will have to get used to that a top end bike is on the wrong side of 20.000$, which I don't see happening anytime soon

    I split the rotor by cutting it with a metal saw by hand. No fancy equipment involved, which by the way is the case for all the stuff I make. It's all handmade, on manual machines, and with hand tools.


    Magura

  28. #128
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    Quote Originally Posted by Mr.Magura View Post
    It sure is fine entertainment.

    The mainstream brands I would guess, have no particular interest in developing much faster than the competitors, and as you can see previously in this thread, there is a strong opposition to spending that kind of money by the general consumer.
    If we wanted some hefty development in the MTB market, people will have to get used to that a top end bike is on the wrong side of 20.000$, which I don't see happening anytime soon

    I split the rotor by cutting it with a metal saw by hand. No fancy equipment involved, which by the way is the case for all the stuff I make. It's all handmade, on manual machines, and with hand tools.


    Magura
    Do you have a cnc machine or do you just use a lathe and a milling machine?

  29. #129
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    Quote Originally Posted by jpeters View Post
    Do you have a cnc machine or do you just use a lathe and a milling machine?
    I have no CNC machinery. All my machines are manual.

    The heftiest machine I have, is a 6 axis grinding machine (also manual).
    I don't know what they're called in English, but in German it's a "stikkel sleifer".



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  30. #130
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    Quote Originally Posted by Mr.Magura View Post
    I have no CNC machinery. All my machines are manual.

    The heftiest machine I have, is a 6 axis grinding machine (also manual).
    I don't know what they're called in English, but in German it's a "stikkel sleifer".



    Magura
    Are you talking about a milling machine?

  31. #131
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    Thanks!

    Quote Originally Posted by Mr.Magura View Post
    The 100$ figure is for pads for one brake.

    Shipping to Flensburg can't be all that expensive, so 30 DKK sounds about right.
    I just sent a piece of Carbenix big enough for a set of pads to California, and that cost me 50 DKK (10$).


    Magura
    Next time I'm over there in the good 'ole DK, I'l buy you a few fat beers... and not frickin' Tuborg (unless that is what you like ).

    It took 4 of those to get my 2 year old to go to sleep!

    <a href="https://picasaweb.google.com/lh/photo/QbfOz2Hud4qX3x1CGWCs8g?feat=embedwebsite"><img src="https://lh3.googleusercontent.com/-Jrc3YUXcjts/S_oUSw5lQxI/AAAAAAAAOhA/_BHuVFMSbGM/s800/IMG_6165.JPG" height="800" width="600" /></a>

    (okay, I didn't really give them to my two year old! It was a bad joke, allright?!? My wife hates this pic. )
    Last edited by pimpbot; 07-17-2011 at 08:31 AM.

  32. #132
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    Quote Originally Posted by jpeters View Post
    Are you talking about a milling machine?
    No, both my milling machines are only 5 axis.

    This is the grinding machine :

    http://www.bnmaskiner.dk/index.pl?ch...arenummer=6065

    I was lucky to find a brand new one a few month ago. I think they have not been made the last 15 years. Back then they were very expensive, starting from 15.000€ and up.
    Today very few people are able to use them, so I got a brand new one for like 1.600€


    Magura

  33. #133
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    Quote Originally Posted by pimpbot View Post
    Next time I'm over there in the good 'ole DK, I'l buy you a few fat beers... and not frickin' Tuborg (unless that is what you like ).
    You just have some fun with the Carbenix, and let me know what it turns out like for you.

    As for beers, I don't drink that stuff usually, red wine and bubbly are the house drinks here.
    I grew up with Tuborg, and to be honest, I think they can take credit for me disliking beer in general today

    Anyhow, we can drink ourselves clever in San Francisco in October. It is sure now that I'll be going. Rumor has it that there will be a fresh supply of Serbian Rakija of the better kind.


    Magura

    EDIT:

    Btw., that is child abuse! Next time I see you feeding him Tuborg, I will have to let the social authorities in on it.
    For crying out loud, give the kid a Guinness or some other decent beer

  34. #134
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    380 volt?

    Quote Originally Posted by Mr.Magura View Post
    No, both my milling machines are only 5 axis.

    This is the grinding machine :

    http://www.bnmaskiner.dk/index.pl?ch...arenummer=6065

    I was lucky to find a brand new one a few month ago. I think they have not been made the last 15 years. Back then they were very expensive, starting from 15.000€ and up.
    Today very few people are able to use them, so I got a brand new one for like 1.600€


    Magura
    I always wondered how they do other power feeds in Europe. Here, we normally have 120 volt, and 240v single phase available. We normally have two 120v circuits fed to a normal house, out of phase from each other. We hang half of the circuits of one phase, and the other half on the other phase. Tie the ends together for 240v for bigger draw for clothes dryers, electric car chargers, electric water heaters, etc. More industrial applications use 3 120v circuits for three phase 480v, and so on. I work on outdoor turbine sirens (alarms) that run on three phase 480v.

    I wonder how you get 380v out of 220v circuits? I guess I should just wikipedia search it.

    Heh... 220v is funny. We plug any of our US electronics in over there (designed for 120v-240v, auto voltage switching) and it flashes and arcs like crazy.

  35. #135
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    Quote Originally Posted by pimpbot View Post
    I always wondered how they do other power feeds in Europe. Here, we normally have 120 volt, and 240v single phase available. We normally have two 120v circuits fed to a normal house, out of phase from each other. We hang half of the circuits of one phase, and the other half on the other phase. Tie the ends together for 240v for bigger draw for clothes dryers, electric car chargers, electric water heaters, etc. More industrial applications use 3 120v circuits for three phase 480v, and so on. I work on outdoor turbine sirens (alarms) that run on three phase 480v.

    I wonder how you get 380v out of 220v circuits? I guess I should just wikipedia search it.

    Heh... 220v is funny. We plug any of our US electronics in over there (designed for 120v-240v, auto voltage switching) and it flashes and arcs like crazy.

    380V is made of 3 x 220V here. Exactly how that works out, is out of my field, but wild guessing would be that it's a matter of phase relations. For my 3 phase equipment, I run a frequency converter off of single phase 220V, and let the electronics take care of the rest. That makes for adjustable speed for the machines to boot, which comes in handy.

    Magura

  36. #136
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    Heck yeah!

    Quote Originally Posted by Mr.Magura View Post

    Anyhow, we can drink ourselves clever in San Francisco in October. It is sure now that I'll be going. Rumor has it that there will be a fresh supply of Serbian Rakija of the better kind.

    You're on! How long are you going to stay here?

    I had a German foreign exchange student stay with me back in 1997 for a year. He and is spouse are also coming out to stay with me a few weeks for a visit in early October. I don't know what my social schedule will be like, but we can probably get a ride and drinks to happen some time, that is, if you can slum it on one my lower rent bikes . Bring your pedals, helmet, clothes and shoes, and I'll make the rest happen. I'm sure my wife will like to blow the cobwebs off her Danish and talk with you a bit.

    Man, I'll give the Russians some props... Those folks know how to drink.
    Last edited by pimpbot; 07-17-2011 at 09:22 AM.

  37. #137
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    Quote Originally Posted by pimpbot View Post
    You're on! How long are you going to stay here?

    I had a German foreign exchange student stay with me back in 1997 for a year. He and is spouse are also coming out to stay with me a few weeks for a visit in early October. I don't know what my social schedule will be like, but we can probably get a ride and drinks to happen some time, that is, if you can slum it on one my lower rent bikes . Bring your pedals, helmet, clothes and shoes, and I'll make the rest happen. I'm sure my wife will like to blow the cobwebs off her Danish and talk with you a bit.

    Man, I'll give the Russians some props... Those folks know how to drink.
    I'm gonna be in SF for a couple of weeks (early October), as I have to attend an audio conference there, and visit a couple of friends.

    I am by no means a good rider, so just about anything with wheels will be perfectly fine for my skill level. I'll stuff my gear and pedals in the suitcase.

    So your wife speaks Danish? That's rather strange for an American. She would be the second American I see, whom have taken a shot at learning Danish.

    I had a Russian drinking tutor, does that count?


    Magura

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    On a more serious note, I managed to get the casting of the composite spider done today as well.
    I added 3% CNT (carbon multi wall nanotubes) to the resin, to get it temperature stable up to 200C (gives me like 35-40C+), which I expect should do the trick. The infrared radiation from the carbon rotor is almost double of the polished steel rotors, so temperature should never exceed 200C for extended periods of time.

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    A pic of the fiber that went into the composite spider.

    The types are:
    321g/m2 UD carbon
    200g/m2 twill




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    Very nice Mr Magura. Once again, thanks for sharing your information on this project.

    Don't let the internet "experts" on everything from engineering to materials science put you off.

    "You never know until you give it a red hot go".

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    Got it out of the mould just 10 min. ago.
    Looks like it stayed straight during the high temp post curing, which was my main concern.

    More pics later today.

    Magura

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    Here is the rotor fresh out of the washing machine.
    You can see in the pic, that the brake surface is not 100% dry yet.

    Now all that's left to do, is to drill the mounting holes. and make a set of pads for it, and the prototype is good to go.


    Magura

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    It just dawned on me, that this would have looked fantastic with a layer of Textreme as top layer

    That sure will be the solution next time around.


    Magura

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    Nice !! looks good

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    Quote Originally Posted by jpeters View Post
    Nice !! looks good
    Thanks.


    Here is a pic of the finished rotor.

    I will though most likely reduce the carrier a bit, if things works as expected. Drilling a few 40mm holes would leave it plenty strong enough, and save some weight.


    Magura

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    Guess a hub


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    That looks nuts!

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    Quote Originally Posted by Neily03 View Post
    That looks nuts!
    Just wait, it gets worse

    I have made the caliper 1.5mm wider, now that looks like a lot



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    Well, I thought I could have had a quick test ride tonight, but things took more effort than
    Expected. I ended up rebuilding the caliper, as the pistons needed some attention,
    And I also had to make the caliper 1.5mm wider, to make room for the 3.5mm thick rotor.
    New pads of a different type of Carbenix is also a must.
    Today I put like 5 hours in the project, finished up the rotor and the caliper.
    Tomorrow I hope to get a test ride.


    Magura

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    Excellent. What's the proto rotor dimensions (203mm?) and weight?

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    This is a really interesting project. I'm curious to hear how they work out for you. I have heard that carbon rotors must get really hot before they work well (hotter than most bike rotors get under braking) but again would be interested in hearing your experiences with them. I would also like to see a picture of them on a scale or at least hear how much they weigh. Nice work.
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    Quote Originally Posted by TigWorld View Post
    Excellent. What's the proto rotor dimensions (203mm?) and weight?
    Yes it's a 203mm.

    The current weight is 170g, but after the initial test I'll get it down around 130g.
    I just couldn't be bothered to do anything about the weight, till I know I like the way it performs.


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    Quote Originally Posted by mtbnozpikr View Post
    This is a really interesting project. I'm curious to hear how they work out for you. I have heard that carbon rotors must get really hot before they work well (hotter than most bike rotors get under braking) but again would be interested in hearing your experiences with them. I would also like to see a picture of them on a scale or at least hear how much they weigh. Nice work.
    Let's debunk the "carbon based brakes must be glowing red to work" myth.

    It entirely depends which type of carbon is used. A good example is that you now can see, that carbon brakes have found their way to street cars.
    I have been working with development of carbon brakes for performance cars in the past, an can assure you that carbon brakes also work when cold.

    There is a little piece of math that it seems most people forget about here. For instance a formula 1 car, is a weight hunting project. To make the brakes as small as possible, they choose a carbon type designed to work at higher temperatures, thus rendering the infrared emission much higher, allowing for a smaller brake to dissipate more heat, which is basically what brakes are all about, converting energy to heat.
    For a bike brake we don't have unlimited dissipation usually, so a heat sink on the pads to keep the generated heat, from overheating the caliper and boiling the brake fluid, seems like a good starting point (see thermographic images earlier in this thread).
    Next step would be to be able to dissipate more heat through the rotor, which can either be achieved through having more surface, or higher dissipation per mm2. The higher dissipation per mm2, can be achieved by either using a material with higher dissipation factor, or by increasing the working temperature.
    Now by using brake pads with specific directional heat transfer characteristics, higher dissipation factor than regular steel backed pads, and adding a heat sink, I have managed to keep the temperature of the caliper down (see first part of this thread).
    The next step is to increase the allowed working temperature of the rotor, which was achieved by using carbon. This also results in higher dissipation due to the higher infrared emission, based on a higher working temperature under heavy load.
    Add to that the factor of approximately 2 of increased emission, due to the material (compared to steel rotors), and you can see where this is heading.


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    The current weight is 170g, but after the initial test I'll get it down around 130g.
    170g is a good weight for a 203mm rotor. 130g is a great weight for such a size, particularly given the thicker rotor surface.

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    Quote Originally Posted by TigWorld View Post
    170g is a good weight for a 203mm rotor. 130g is a great weight for such a size, particularly given the thicker rotor surface.
    You have to keep in mind, that the density of carbon (2.2), is much lower than of steel (7.8), so relatively low weight was to be expected.


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    Quote Originally Posted by Mr.Magura View Post
    Let's debunk the "carbon based brakes must be glowing red to work" myth.

    It entirely depends which type of carbon is used. A good example is that you now can see, that carbon brakes have found their way to street cars.
    I have been working with development of carbon brakes for performance cars in the past, an can assure you that carbon brakes also work when cold.

    There is a little piece of math that it seems most people forget about here. For instance a formula 1 car, is a weight hunting project. To make the brakes as small as possible, they choose a carbon type designed to work at higher temperatures, thus rendering the infrared emission much higher, allowing for a smaller brake to dissipate more heat, which is basically what brakes are all about, converting energy to heat.
    For a bike brake we don't have unlimited dissipation usually, so a heat sink on the pads to keep the generated heat, from overheating the caliper and boiling the brake fluid, seems like a good starting point (see thermographic images earlier in this thread).
    Next step would be to be able to dissipate more heat through the rotor, which can either be achieved through having more surface, or higher dissipation per mm2. The higher dissipation per mm2, can be achieved by either using a material with higher dissipation factor, or by increasing the working temperature.
    Now by using brake pads with specific directional heat transfer characteristics, higher dissipation factor than regular steel backed pads, and adding a heat sink, I have managed to keep the temperature of the caliper down (see first part of this thread).
    The next step is to increase the allowed working temperature of the rotor, which was achieved by using carbon. This also results in higher dissipation due to the higher infrared emission, based on a higher working temperature under heavy load.
    Add to that the factor of approximately 2 of increased emission, due to the material (compared to steel rotors), and you can see where this is heading.


    Magura
    That's all well and good, but you have completely failed to explain why this carbon will work at the relatively cool braking temperatures of mountain bikes (compared to road cars, F1 cars & fighter jets). You've gone on and on about heat dissipation, but said nothing about working temperatures.

    And to be clear, it isn't a myth that carbon-carbon requires higher temperatures, at least, as you point out, some carbon-carbon composites (such as those used in F1). Clearly, a minimum of 750* F is higher than standard steel rotors.

    It'll be cool when you get these done to do some repeatable tests, like towing your bike with a car at a given speed, say 25 MPH and see which stops faster (similar to how automotive brakes are tested).

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    Quote Originally Posted by deadbolt View Post
    That's all well and good, but you have completely failed to explain why this carbon will work at the relatively cool braking temperatures of mountain bikes (compared to road cars, F1 cars & fighter jets). You've gone on and on about heat dissipation, but said nothing about working temperatures.

    And to be clear, it isn't a myth that carbon-carbon requires higher temperatures, at least, as you point out, some carbon-carbon composites (such as those used in F1). Clearly, a minimum of 750* F is higher than standard steel rotors.

    It'll be cool when you get these done to do some repeatable tests, like towing your bike with a car at a given speed, say 25 MPH and see which stops faster (similar to how automotive brakes are tested).
    If you read my previous post once more, you'll see that I explained that there are types of carbon that works at different temperatures.
    F1 is sure a high temp. type, but for instance the type used for the fighter planes, is not.
    The type used for planes has a maximum working temperature, around 600C, and are working from temperatures below 0C. The type used for planes actually get damaged above 600C due to oxidation.
    For a road car, you also don't have the high temp. types in use, as they also need brake power at any temperature.
    The previous brakes I engineered for a performance car, were running at maximum 350C as I recall, and most of the time, they were below 100C during regular driving.

    Try reading up on the different types of carbon based friction materials. Just from Honeywell you will see a few different types, with very different characteristics.


    Magura


    EDIT: If you read the rest of the thread, you will see that it already has proven to be working, when used for pads. The friction properties of steel are much lower than of carbon, so adding a carbon rotor to the equation, will only improve things. How much it will improve the performance, is depending on a few factors, but a rough calculation says around 50%.

  58. #158
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    Quote Originally Posted by deadbolt View Post
    That's all well and good, but you have completely failed to explain why this carbon will work at the relatively cool braking temperatures of mountain bikes (compared to road cars, F1 cars & fighter jets). You've gone on and on about heat dissipation, but said nothing about working temperatures...
    Why should he bother explaining anything (although he has already done so repeatedly in this thread)? He's not engaging in some hypothetical/theoretical internet type off. The guy's built a rotor and is about to give it a go on his bike. It's not going to take a lot of riding to know if it actually works or not. I'm sure we'll get a ride report and then we'll all know whether that particular carbon based braking compound / brake pad combo works or not.

    I just don't get the armchair negativity. If you've built one of these rotors from the same material as Mr Magura is using and the results were less then spectacular, then by all means jump in and save the bloke from "wasting" his time. If you haven't, then sit back and enjoy the information the bloke's sharing.

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    Quote Originally Posted by Mr.Magura View Post
    If you read my previous post once more, you'll see that I explained that there are types of carbon that works at different temperatures.
    F1 is sure a high temp. type, but for instance the type used for the fighter planes, is not.
    The type used for planes has a maximum working temperature, around 600C, and are working from temperatures below 0C. The type used for planes actually get damaged above 600C due to oxidation.
    For a road car, you also don't have the high temp. types in use, as they also need brake power at any temperature.
    The previous brakes I engineered for a performance car, were running at maximum 350C as I recall, and most of the time, they were below 100C during regular driving.

    Try reading up on the different types of carbon based friction materials. Just from Honeywell you will see a few different types, with very different characteristics.


    Magura


    EDIT: If you read the rest of the thread, you will see that it already has proven to be working, when used for pads. The friction properties of steel are much lower than of carbon, so adding a carbon rotor to the equation, will only improve things. How much it will improve the performance, is depending on a few factors, but a rough calculation says around 50%.


    I've read your posts very carefully. You keep saying that carbon-carbon brakes requiring higher temperatures is a myth. Then you go on to say that some composites are specifically designed to operate at lower temperatures. 100*C is 212*F, that's still awfully hot for an mtb rotor…

    I can see the c-c pads working on steel rotors, it's the c-c rotor that has me skeptical.

    From the little research I've done, I see that Carbonex was formulated to reduce oxidation, but still has an operating temperature of 700*C (~1300*F):

    "The results shown in Figure 1 clearly show that the catalytic effect of potassium acetate is most profound in the 700°C region and diminishes significantly at higher temperatures. This is in agreement with the prevailing theory that Group I metals catalyze by assisting in "active site" formation and that this step is the rate limiting step in this temperature range [3], which also happens to be the typical operating temperature range for carbon/carbon friction materials." http://acs.omnibooksonline.com/data/...1997_ii498.pdf

    The static coefficient of friction for a standard brake material on cast iron is ~0.4; carbon-carbon: ~0.6, so I wouldn't say steel is much lower. The advantage to carbon-carbon, at least for race cars, is the amount of heat they can take and their considerable weight savings. Decelerating a Formula 1 car at up to 6G's produces a LOT of heat…

    The literature I quoted is a little dated, if you have literature or a data sheet that shows the operating temperature for the materials your using I'd love to see them.

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    Quote Originally Posted by deadbolt View Post
    I've read your posts very carefully. You keep saying that carbon-carbon brakes requiring higher temperatures is a myth. Then you go on to say that some composites are specifically designed to operate at lower temperatures. 100*C is 212*F, that's still awfully hot for an mtb rotor…

    I can see the c-c pads working on steel rotors, it's the c-c rotor that has me skeptical.

    From the little research I've done, I see that Carbonex was formulated to reduce oxidation, but still has an operating temperature of 700*C (~1300*F):

    "The results shown in Figure 1 clearly show that the catalytic effect of potassium acetate is most profound in the 700°C region and diminishes significantly at higher temperatures. This is in agreement with the prevailing theory that Group I metals catalyze by assisting in "active site" formation and that this step is the rate limiting step in this temperature range [3], which also happens to be the typical operating temperature range for carbon/carbon friction materials." http://acs.omnibooksonline.com/data/...1997_ii498.pdf

    The static coefficient of friction for a standard brake material on cast iron is ~0.4; carbon-carbon: ~0.6, so I wouldn't say steel is much lower. The advantage to carbon-carbon, at least for race cars, is the amount of heat they can take and their considerable weight savings. Decelerating a Formula 1 car at up to 6G's produces a LOT of heat…

    The literature I quoted is a little dated, if you have literature or a data sheet that shows the operating temperature for the materials your using I'd love to see them.
    Your information is not a little outdated, but very much outdated.



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    Quote Originally Posted by TigWorld View Post
    Why should he bother explaining anything (although he has already done so repeatedly in this thread)? He's not engaging in some hypothetical/theoretical internet type off. The guy's built a rotor and is about to give it a go on his bike. It's not going to take a lot of riding to know if it actually works or not. I'm sure we'll get a ride report and then we'll all know whether that particular carbon based braking compound / brake pad combo works or not.

    I just don't get the armchair negativity. If you've built one of these rotors from the same material as Mr Magura is using and the results were less then spectacular, then by all means jump in and save the bloke from "wasting" his time. If you haven't, then sit back and enjoy the information the bloke's sharing.
    Ok, you seem like a nice guy, so I'll help you out there.

    You see those who can, do. Those who can't, teach. Those who can't teach, teach gym.

    If people can't even teach gym, no wonder they're so negative

    Magura

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    Quote Originally Posted by Mr.Magura View Post
    Let's debunk the "carbon based brakes must be glowing red to work" myth.

    It entirely depends which type of carbon is used. A good example is that you now can see, that carbon brakes have found their way to street cars.
    I have been working with development of carbon brakes for performance cars in the past, an can assure you that carbon brakes also work when cold.

    There is a little piece of math that it seems most people forget about here. For instance a formula 1 car, is a weight hunting project. To make the brakes as small as possible, they choose a carbon type designed to work at higher temperatures, thus rendering the infrared emission much higher, allowing for a smaller brake to dissipate more heat, which is basically what brakes are all about, converting energy to heat.
    For a bike brake we don't have unlimited dissipation usually, so a heat sink on the pads to keep the generated heat, from overheating the caliper and boiling the brake fluid, seems like a good starting point (see thermographic images earlier in this thread).
    Next step would be to be able to dissipate more heat through the rotor, which can either be achieved through having more surface, or higher dissipation per mm2. The higher dissipation per mm2, can be achieved by either using a material with higher dissipation factor, or by increasing the working temperature.
    Now by using brake pads with specific directional heat transfer characteristics, higher dissipation factor than regular steel backed pads, and adding a heat sink, I have managed to keep the temperature of the caliper down (see first part of this thread).
    The next step is to increase the allowed working temperature of the rotor, which was achieved by using carbon. This also results in higher dissipation due to the higher infrared emission, based on a higher working temperature under heavy load.
    Add to that the factor of approximately 2 of increased emission, due to the material (compared to steel rotors), and you can see where this is heading.


    Magura
    I'm glad to see that you know your principles of heat transfer. Obviously the thermoconductivity (k) of carbon is much much less than steel therefore for the same heat put in, more will be dissipated as you mentioned. Did you also take into consideration the convection coefficient (h)? Much more complicated than thermoconductivity (you probably know) but important nonetheless. Reynolds numbers which are obviously dependent on velocity, Nusselt numbers, and finally heat transferred. Did you consider convection as negligible because the convection is so low?

    You seem like a very well versed person when it comes to this kind of stuff (mechanical engineer?) so I'm sure nothing fell between the cracks. Great work. I look forward to hearing actual performance information/reviews.
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    Quote Originally Posted by deadbolt View Post
    [i][color=blue]The static coefficient of friction for a standard brake material on cast iron is ~0.4; carbon-carbon: ~0.6, so I wouldn't say steel is much lower.
    Wouldn't we be talking kinetic friction here since usually you try not to lock up your wheels? Also, since friction coefficients are between 0 and around 1 (maybe a little greater), 0.2 difference is significant.
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    Quote Originally Posted by mtbnozpikr View Post
    I'm glad to see that you know your principles of heat transfer. Obviously the thermoconductivity (k) of carbon is much much less than steel therefore for the same heat put in, more will be dissipated as you mentioned. Did you also take into consideration the convection coefficient (h)? Much more complicated than thermoconductivity (you probably know) but important nonetheless. Reynolds numbers which are obviously dependent on velocity, Nusselt numbers, and finally heat transferred. Did you consider convection as negligible because the convection is so low?

    You seem like a very well versed person when it comes to this kind of stuff (mechanical engineer?) so I'm sure nothing fell between the cracks. Great work. I look forward to hearing actual performance information/reviews.
    You got a point there about convection, but I have simply left it out, as it would be close to the same for both steel and carbon.
    As you say, the calculations for convection cooling are much more complicated, but to some extend they can be simplified, with only small deviations from the full monty, when it's something as relatively simple as this.

    The thermal conductivity of carbon is actually better than of steel. For the type of carbon in question, it's thermal conductivity is between aluminium and copper.
    However a property of carbon that is much more interesting, is that it can be having direction dependent thermal conductivity. That is actually what I have taken advantage of with the pads, so the thermal transfer is higher in the direction from the pad to the heat sink, than from the pad to the caliper.
    After I finished up the first carbon brake project for a car, I was so fascinated by the thermal properties of carbon based materials, that I used it for thermal management of an audio amplifier I built at the time. The active devices are all situated in one side, within 50 x 100mm. The heat sinks are all around the chassis. The temperature difference from one end to the other of the chassis, is less than 1C.
    The pic is from one of the first test runs of the amplifier. On the pic it's hard to see, but it is 60 cm in diameter, and weighs in around 90 kg.


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    Quote Originally Posted by mtbnozpikr View Post
    Wouldn't we be talking kinetic friction here since usually you try not to lock up your wheels? Also, since friction coefficients are between 0 and around 1 (maybe a little greater), 0.2 difference is significant.
    Yes, 0.2 is a 50% increase of 0.4. I would tend to agree that 50% is significant.

    Now please quit confusing people with facts


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    I just got back from a quick test ride.

    That brake is simply brutal!

    The limiting factor seems to be tire grip and courage.

    A 203mm rotor is sure overkill now.

    Only issue so far, was initial screaming, but that seems to be gone now.


    Magura

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    A couple of pics of the final setup.


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    You are the man you made carbon rotors and pads from scratch NICE!!! But I bet people we be saying prove it any 203 mm brake will work good That looks so cool you have a 3000 dollar set of brakes on your MTB lol hate to brake one of those babies lol. When you get a chance find a nice big hill and let us know how they do. Will you keep them on ? I hope I get a chance to come try them.

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    Quote Originally Posted by jpeters View Post
    You are the man you made carbon rotors and pads from scratch NICE!!! But I bet people we be saying prove it any 203 mm brake will work good That looks so cool you have a 3000 dollar set of brakes on your MTB lol hate to brake one of those babies lol. When you get a chance find a nice big hill and let us know how they do. Will you keep them on ? I hope I get a chance to come try them.
    Well, I'm in the fortunate situation, that I don't care too much what people say.
    I'm having a good time, the stuff I play with tends to work well, and I've paid for it myself

    Speaking of paying, no reason to make this seem more crazy than it is, it's only going to go on the front end, so we are down to 1.500$ per bike

    I will do some testing the following days. I want to get a thermographic image to compare to the previous tests, and I want to see if I can overload it somehow, just to see what fails first.
    I though seem to have a small problem, as I am not sure I like how much my fork deflects when applying the brake. So far I have maybe run like 2/3 of maximum power, and it looked scary to say the least.

    I will keep it on at least till I'm done testing. Then I'll save it for next time I'm in a place where they could be more fun.

    You have had an invitation, so feel free to make use of it.


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    Quote Originally Posted by Mr.Magura View Post
    Well, I'm in the fortunate situation, that I don't care too much what people say.
    I'm having a good time, the stuff I play with tends to work well, and I've paid for it myself

    Speaking of paying, no reason to make this seem more crazy than it is, it's only going to go on the front end, so we are down to 1.500$ per bike

    I will do some testing the following days. I want to get a thermographic image to compare to the previous tests, and I want to see if I can overload it somehow, just to see what fails first.
    I though seem to have a small problem, as I am not sure I like how much my fork deflects when applying the brake. So far I have maybe run like 2/3 of maximum power, and it looked scary to say the least.

    I will keep it on at least till I'm done testing. Then I'll save it for next time I'm in a place where they could be more fun.

    You have had an invitation, so feel free to make use of it.


    Magura
    Yeah that is all that counts have fun with it. I love to tinker with stuff like that I wish I had the know how and the funds to do so. Thanks For sharing your experience

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    A guy who is working for a brake manufacturer, and also a MTBR member, gave me an idea for the next step by the way.

    He had been tinkering with cooling down the brake fluid. Now if I could make that work, I could ditch the heat sinks, and simply forget about heat issues completely.

    Unfortunately his policy is to not join in on threads, unless there is a specific question regarding one of his products, but I know he is following this thread, hence the reference, so he could get some credit for the idea.

    Magura

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    Quote Originally Posted by Mr.Magura View Post
    A guy who is working for a brake manufacturer, and also a MTBR member, gave me an idea for the next step by the way.

    He had been tinkering with cooling down the brake fluid. Now if I could make that work, I could ditch the heat sinks, and simply forget about heat issues completely.

    Unfortunately his policy is to not join in on threads, unless there is a specific question regarding one of his products, but I know he is following this thread, hence the reference, so he could get some credit for the idea.

    Magura
    I do not see how you could keep the fluid cool. Possibly by adding a heat sink to the caliper? It would need to be big and get a lot of air like a rc car motor heat sink or maybe a heatsink with internal lines running through like a oil cooler.


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    Quote Originally Posted by jpeters View Post
    I do not see how you could keep the fluid cool. Possibly by adding a heat sink to the caliper? It would need to be big and get a lot of air like a rc car motor heat sink or maybe a heatsink with internal lines running through like a oil cooler.


    http://www.google.com/search?hl=en&q...og&sa=N&tab=wi
    I just tossed the idea out, without having given it much thought yet.

    A solution could be to run 2 hydraulic lines, and circulate the fluid. If done like that, the lines could just be attached to the frame with adhesive thermal tape, and let the frame take care of the dissipation. That way the caliper would get fresh cold fluid, every time the lever is operated.

    This I do admit is a half baked solution, and sure something that needs more thought still.


    Magura

  74. #174
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    Hmmm, yeah...

    Quote Originally Posted by Mr.Magura View Post
    I just tossed the idea out, without having given it much thought yet.

    A solution could be to run 2 hydraulic lines, and circulate the fluid. If done like that, the lines could just be attached to the frame with adhesive thermal tape, and let the frame take care of the dissipation. That way the caliper would get fresh cold fluid, every time the lever is operated.

    This I do admit is a half baked solution, and sure something that needs more thought still.


    Magura
    Maybe some sort of one way valve on one side of two lines. Both lines get pressurized during braking, then as the brake returns to normal, the fluid only returns one direction, maybe through a tubular heat sink. It will get you a bit of circulation, might not be enough to do a whole lot, but given that the current systems give you exactly none, it has to be an improvement. Would probably be fairly easy to rig up... maybe a drill and tap a second port on the caliper. Might make it a total PITA to bleed.

  75. #175
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    Quote Originally Posted by pimpbot View Post
    Maybe some sort of one way valve on one side of two lines. Both lines get pressurized during braking, then as the brake returns to normal, the fluid only returns one direction, maybe through a tubular heat sink. It will get you a bit of circulation, might not be enough to do a whole lot, but given that the current systems give you exactly none, it has to be an improvement. Would probably be fairly easy to rig up... maybe a drill and tap a second port on the caliper. Might make it a total PITA to bleed.
    My initial idea is to put one way valves on both lines, connect the return line to the bleed port of the caliper, and connect the two lines close to the lever.
    One valve only is not working, as the fluid will take the easiest path, thus the line without the valve.
    If done like proposed above, bleeding would become a walk in the park, as all that would be needed, would be to add fluid till there is no more air in the system.

    After thinking a bit more about it, the hydraulic lines may be enough to cool down the fluid, as they actually have a lot of surface.

    Have you received anything yet? It should have reached you yesterday.

    Magura

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    Now after I have gotten some time with this brake, a small update.

    It seems that everything is as it should be.
    Wear seems minimal, and power is plenty. I had it on a big hill today, and power actually increases a bit as it heats up, some 10% or so. Modulation is about the same as the original Hope M4, which is not half bad in my book.
    I am yet to get some more hard proof, as the weather has been less than co-operative.
    For getting some respectable measurements, I need preferably no wind at all, or it will throw off the results by a mile.


    Magura

  77. #177
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    Quote Originally Posted by OO7 View Post
    You'z gonna have FIGHTER JET brakes?
    I know right?

    You'd think Mr.Magura would re-work some carbon carbon off the old space shuttle
    (that was a joke)

  78. #178
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    Quote Originally Posted by Mr.Magura View Post
    A guy who is working for a brake manufacturer, and also a MTBR member, gave me an idea for the next step by the way.

    He had been tinkering with cooling down the brake fluid. Now if I could make that work, I could ditch the heat sinks, and simply forget about heat issues completely.

    Unfortunately his policy is to not join in on threads, unless there is a specific question regarding one of his products, but I know he is following this thread, hence the reference, so he could get some credit for the idea.

    Magura
    Perhaps a capilary style (like in phase change where the outgoing line cools the return line) redundant return line? The redundant coil would act like a reservoir upping the heat capacity.

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    Quote Originally Posted by weescott View Post
    Perhaps a capilary style (like in phase change where the outgoing line cools the return line) redundant return line? The redundant coil would act like a reservoir upping the heat capacity.
    Could you elaborate a bit?

    I'm not sure I follow your train of thought.


    Magura

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    Quote Originally Posted by DeerhillJDOG View Post
    I know right?

    You'd think Mr.Magura would re-work some carbon carbon off the old space shuttle
    (that was a joke)

    Hey now that they don't need the space shuttle anymore, maybe.........



    Magura

  81. #181
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    Quote Originally Posted by deadbolt View Post
    I've read your posts very carefully. You keep saying that carbon-carbon brakes requiring higher temperatures is a myth. Then you go on to say that some composites are specifically designed to operate at lower temperatures. 100*C is 212*F, that's still awfully hot for an mtb rotor…
    Sorry, but 100ºC is not an "awfully hot" temperature at all.

    I haven't measured disc temperature using proper devices (I'd like to carry a thermocouple or a thermal imaging camera on my rides, but the bag is always too full to carry them ), but I'm sure that exceeds 100 ºC as any water that contacts the discs boils violently, after descending a steep section. (And, no, I don't live on top of the mt. Everest and the water boils here at 97-98 ºC)
    A pessimist is an experienced optimist

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    Quote Originally Posted by Pableras View Post
    Sorry, but 100ºC is not an "awfully hot" temperature at all.

    I haven't measured disc temperature using proper devices (I'd like to carry a thermocouple or a thermal imaging camera on my rides, but the bag is always too full to carry them ), but I'm sure that exceeds 100 ºC as any water that contacts the discs boils violently, after descending a steep section. (And, no, I don't live on top of the mt. Everest and the water boils here at 97-98 ºC)
    True, 100C is not much at all for a rotor. My stainless steel rotor got colored from the heat, which sure does not happen at 100C.
    Besides that it looses about 10% of the power at 20C, which still means a gain of 25% in worst case scenarios. Most of the time, it will be above 100C, or get there real quick.

    Magura

  83. #183
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    I do concur however it may be that its relatively easy now to provide too much brake and that traction is the limiting factor at the wheel this has been proved in testing as well as rotors seeing well over 100 degrees. I think stiffer calipers with bigger oil volume might be interestiing .

  84. #184
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    Nothing to add, but Pimpbot and Mr. Magura.....GREAT THREAD ! Thank you
    Poaching Demo...that's why we can't have nice things...

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    Quote Originally Posted by compositepro View Post
    I do concur however it may be that its relatively easy now to provide too much brake and that traction is the limiting factor at the wheel this has been proved in testing as well as rotors seeing well over 100 degrees. I think stiffer calipers with bigger oil volume might be interestiing .
    I agree that the next natural step is stiffer calipers. Oil volume is debatable, as the volume would be better placed away from the caliper.


    You got mail.


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  86. #186
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    I'm not sure what to say, FIGHTER JET BRAKES ON A MTB!!!!! you sir are my idol. I want to try something more like Pimpbot's idea (read "cheaper") some time this summer. I can't wait to see where this thread goes. Magura, will this brake ever end up on your custom carbon DH rig?

  87. #187
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    Quote Originally Posted by elcoolio1 View Post
    I'm not sure what to say, FIGHTER JET BRAKES ON A MTB!!!!! you sir are my idol. I want to try something more like Pimpbot's idea (read "cheaper") some time this summer. I can't wait to see where this thread goes. Magura, will this brake ever end up on your custom carbon DH rig?
    The brake is sure going on the carbon DH rig, you know, for color coordination purposes

    Next step for me (after getting a bit of measurements of the brake setup) is to finish up the carbon frame, so that I have something a bit more versatile as test rig.

    After that and a trip to the alps, we will see what next step will be, or if any step is needed.




    Magura

  88. #188
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    Quote Originally Posted by Mr.Magura View Post
    Could you elaborate a bit?

    I'm not sure I follow your train of thought.


    Magura
    I think he's referring to heat pipes like they sometimes use to move heat from CPUs so the heat-sink can be bigger than would fit on the CPU

  89. #189
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    shimano did a fluid cooler on a (ridiculously powerful) dual disc brake they built a bunch of years ago:



    magura, you're my hero. mad fabrication skills (following the frame thread as well). the amp looks sick too (details)?

  90. #190
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    werent the racers finding that it was too powerfull though? the dual disc setup.

    anyways, if the fluid is going to get hot enough to be a problem, just include a larger resivoir. once the fluid heats up and expands it will just expand into the resivoir and no longer be a problem. unless you are getting into where you will boil DOT5 fluid, which is very very unlikely on those brakes which insulate the pad heat from the caliper, you shouldnt have to worry.
    if you are braking hard enough to overheat the fluid, I would think a small scoop to grab direct air for cooling to the caliper would be most effective and lightest. since to get that heat you would have to be going very fast.

    buell did this with their latest racebike, they use a huge rim mounted inside out disc on only one side, and it didnt get the air that dual discs in the center get, so it lost performance when it got too hot. they added a small duct into the front fender and improved braking. And thats a bike that goes from 180mph down to probably 30mph as fast as possible in racing. also is what F1 racercars use, I recall the size of the ducts differed depending on the driving style and course, to keep the brakes within their optimal temperature range (however high/low/broad that may be).

    adding more cooling over what you have, at anything less than top tier racing speeds, is likely to just add weight though without any benefit. That would start to be silly. Though, the whole project started as silly, you ended up with a lighter and fiercely powerful result. You may have reached the tipping point where more power CAN be had but cant be used, and will only add weight, and that would then decrease the overall performance.

    Wicked awsome though.
    how does the carbenix have different heat transfer properties in different directions? or is that top secret tech? do they align the grain so as to allow conductivity between ends but not sides of "fibers" or vice versa, are we looking at layered graphene here essentially?
    Last edited by Dichotomous; 07-27-2011 at 11:41 AM.

  91. #191
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    Well, I feel like an idiot after reading this thread

    Amazing job Magura and Pimpbot!
    "Nothing compares to the simple pleasure of a bike ride." - John F. Kennedy

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    11' Giant XTC 2 29er

  92. #192
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    Late to this thread (followed from his frame thread), but Mr.Magura's work is inspiring. I don't agree w/ everything he says but LOVE the fact he does it. (FWIW, I have carbon ceramic brakes on my 996tt and they're definitely weak in the cold and downright lousy when cold AND wet. Plus have VERY low impact tolerance - have to put in 2 pins when taking the wheels on/off to prevent from bumping them.)

    But to solve the pad to caliper heat exchange, take a page from PFCs racing calipers. Use ceramic caps on the pistons to limit convection from the pads. You could probably find a ceramic spray coating (like from Swain?) to put on the inner throat of the caliper to limit the radiation transfer too.

    Keep at it!

  93. #193
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    Quote Originally Posted by smdubovsky View Post
    Late to this thread (followed from his frame thread), but Mr.Magura's work is inspiring. I don't agree w/ everything he says but LOVE the fact he does it. (FWIW, I have carbon ceramic brakes on my 996tt and they're definitely weak in the cold and downright lousy when cold AND wet. Plus have VERY low impact tolerance - have to put in 2 pins when taking the wheels on/off to prevent from bumping them.)

    But to solve the pad to caliper heat exchange, take a page from PFCs racing calipers. Use ceramic caps on the pistons to limit CONDUCTION from the pads. You could probably find a ceramic spray coating (like from Swain?) to put on the inner throat of the caliper to limit the radiation transfer too.

    Keep at it!
    fyp

  94. #194
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    Yeah, thats what I meant. Brain fart

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    Quote Originally Posted by xy9ine View Post
    shimano did a fluid cooler on a (ridiculously powerful) dual disc brake they built a bunch of years ago:



    magura, you're my hero. mad fabrication skills (following the frame thread as well). the amp looks sick too (details)?
    Today I have attempted to overheat the fluid, but did not manage to do so. I had a friend pull me with a moped. I was braking for like 5 minutes, and had no issues.
    So the additional cooling of the caliper is no longer of interest.


    The amplifier is a class A amp (real class A without pseudo bias and the like), biased by an air core inductor of 180mH (the inductor alone is approx. 20 kg of copper), the output stage is a balanced single ended pair of power JFET's, each mono block sports 250.000uF of power supply capacitance, hereof 328uF of DIY PP film capacitors, 2.2mH shielded and cooled inductors, and a 1000VA toroid transformer. Rectifiers are fast soft recovery snubbed discrete diodes.
    The boards were milled, and are made of glass reinforced PTFE, also DIY.
    All the metal and carbon work is DIY, including the bolts and heat sinks. The chassis is cast aluminium, I did the mould and the casting myself. It is in fact made of aluminium car rims from the metal scrap yard.
    The output power can be scaled up to 50W, but is currently running at 20W, which with my speakers offers a sound pressure in my living room of 110dB.
    They draw 180W of electrical power at all times per channel, idle or full throttle makes no difference. The inrush current is pretty brutal, so in order to keep them from blowing fuses left and right, I have a button on each of them for switching on, and they have been equipped with a soft start circuit.
    The sound is among the most natural out there, making acoustic music stand out, but allows for respectable reproduction of Guns 'n' Roses as well

    The first pic is of the remote, the rest should be self explanatory.


    Magura

  96. #196
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    Quote Originally Posted by Dichotomous View Post
    werent the racers finding that it was too powerfull though? the dual disc setup.

    anyways, if the fluid is going to get hot enough to be a problem, just include a larger resivoir. once the fluid heats up and expands it will just expand into the resivoir and no longer be a problem. unless you are getting into where you will boil DOT5 fluid, which is very very unlikely on those brakes which insulate the pad heat from the caliper, you shouldnt have to worry.
    if you are braking hard enough to overheat the fluid, I would think a small scoop to grab direct air for cooling to the caliper would be most effective and lightest. since to get that heat you would have to be going very fast.

    buell did this with their latest racebike, they use a huge rim mounted inside out disc on only one side, and it didnt get the air that dual discs in the center get, so it lost performance when it got too hot. they added a small duct into the front fender and improved braking. And thats a bike that goes from 180mph down to probably 30mph as fast as possible in racing. also is what F1 racercars use, I recall the size of the ducts differed depending on the driving style and course, to keep the brakes within their optimal temperature range (however high/low/broad that may be).

    adding more cooling over what you have, at anything less than top tier racing speeds, is likely to just add weight though without any benefit. That would start to be silly. Though, the whole project started as silly, you ended up with a lighter and fiercely powerful result. You may have reached the tipping point where more power CAN be had but cant be used, and will only add weight, and that would then decrease the overall performance.

    Wicked awsome though.
    how does the carbenix have different heat transfer properties in different directions? or is that top secret tech? do they align the grain so as to allow conductivity between ends but not sides of "fibers" or vice versa, are we looking at layered graphene here essentially?
    The targets were to get plenty of power, and to get completely around fading.
    Those targets have been achieved and even exceeded.

    You are right that there is no need for more power. This is the point where traction is the limiting factor. The only additions I will make to this project are to make the rotor a bit lighter, and I will make ceramic pistons. The ceramic pistons will mostly be due to less maintenance, as the steel pistons tend to need service from time to time to remain smooth running.


    The official reason why some types of Carbenix heat transfer depending on direction, is secret enough for them not to tell me about it, if that's making it top secret, well I don't know.
    My understanding of why, is that the grain is aligned and in layers.


    Magura

  97. #197
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    Quote Originally Posted by nikojan View Post
    Well, I feel like an idiot after reading this thread

    Amazing job Magura and Pimpbot!
    Oh, then we are much alike.
    Some time ago, somebody informed me that I am an idiot too



    Magura

  98. #198
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    I may have missed this information - are you using 2000 or 4000 series Carbenix?

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    Quote Originally Posted by jtmartino View Post
    I may have missed this information - are you using 2000 or 4000 series Carbenix?
    Rotors are 4000, pads are 2000


    Magura

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    Quote Originally Posted by smdubovsky View Post
    Late to this thread (followed from his frame thread), but Mr.Magura's work is inspiring. I don't agree w/ everything he says but LOVE the fact he does it. (FWIW, I have carbon ceramic brakes on my 996tt and they're definitely weak in the cold and downright lousy when cold AND wet. Plus have VERY low impact tolerance - have to put in 2 pins when taking the wheels on/off to prevent from bumping them.)

    But to solve the pad to caliper heat exchange, take a page from PFCs racing calipers. Use ceramic caps on the pistons to limit convection from the pads. You could probably find a ceramic spray coating (like from Swain?) to put on the inner throat of the caliper to limit the radiation transfer too.

    Keep at it!


    The impact tolerance of the brakes on a car, is due to their size. They are not flexible at all, so if they get hit by something, they go south. I had the same problem back when working on car brakes. The brake on the bike, is rather impact resistant, as it's quite flexible.

    Full ceramic pistons are in the pipeline.


    Magura

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