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  1. #1
    j73
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    Carbon clincher being safe for descend on hills or mountains...

    I have a all carbon clincher FSA sl-k wheelset with yellow swissstop pads that came with. Today first time using on a long steep descend with curves, and btw being a wet road from the rain last night. My bike handling skills are not the best, I was using the brakes a lot just to have a constant speed of 15-20mph which if I did not brake as much I will easily reach 30-40mph. I'm 125lbs which I don't think give really a big load for trying to stop, but I notice that when I was trying to ride on the brakes and with the combination of on and off I was smelling burned rubber. Guessing the pads are overheating with rims or other way around. Nothing catastrophic happened, and wheelset were okay I guess...I don't see any changes in the braking surface as of now. My question is, are these normal to be like this when being use on steep hills or I'm just braking too much? I read about threads that carbon clinchers tend to warp or even fail when it overheats. Do I have to improve my braking skills?

  2. #2
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    yes they are pretty safe for most roads and some CC's are better then others.... but it all depends on conditions. I did Levi's Gran Fondo this year and honestly wished I had Al clinchers.. I will next year (Shimano C24's already purchased). The main reason is that I could not descend the way I wanted to because of the traffic and thus rode the brakes pretty hard on -15%.

  3. #3
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    Quote Originally Posted by spdntrxi View Post
    yes they are pretty safe for most roads and some CC's are better then others...
    Very true. As much as Zipp annoys me as a company, their CC compound resin is superior to any other I've ridden. Their cC rims stop as good as aluminum in rain and don't overheat.

  4. #4
    Velocipediologist
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    you will be just fine....................you have the right idea, don't ride the brakes the entire way down

  5. #5
    Boyd Cycling owner
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    I would probably swap out the yellow Swissstop for the Black Prince. Better brake pad and MUCH less heat build up.

    Try to brake in an on/off method. Grab both the front and rear brake at the same time and brake pretty hard for a few seconds, then release both for a few seconds. This will build up the heat and then let it dissipate. Don't drag your brakes for prolonged periods of time or switch between using the front and then the rear brake.
    www.boydcycling.com Handcrafted Revolution

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    .....uhmm, coachboyd, how are we supposed to "grab & release" when we're coming down the Altamont? From the reverse direction, not the normal way up?? On those select few nasty steep sections, there no "grab" or "release"; it's more "squeeze 'em for dear life" and hope we all don't hit one another and/or go sailing off the side of the road...hahahahaha

  7. #7
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    Quote Originally Posted by coachboyd View Post
    ... Better brake pad and MUCH less heat build up...
    Only if it defies the laws of physics. Heat is equal to the kinetic and potential energy being dissipated, nothing else. Resultant temperature is almost entirely dependent on the thermal properties of the rim material and its shape. For example, aluminum has a higher specific heat and is much more thermally conductive than CF so peak temperatures will be lower.
    ... 'cuz that's how I roll.

  8. #8
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    Some burning rubber smell is normal for carbon rims.

    The Yellows are the worst pad for putting heat into rims. When I hear of people ruining their rims it's usually with Yellows. If the rim maker recommends any other pad, try those.

    If you're a poor descender and can only go 20mph on a descent where others can do 40, you should not be on carbon clinchers. If everyone is slowing to 20 for tight turns, then you should reconsider using carbon clinchers for that kind of descent.

  9. #9
    Boyd Cycling owner
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    Quote Originally Posted by looigi View Post
    Only if it defies the laws of physics. Heat is equal to the kinetic and potential energy being dissipated, nothing else. Resultant temperature is almost entirely dependent on the thermal properties of the rim material and its shape. For example, aluminum has a higher specific heat and is much more thermally conductive than CF so peak temperatures will be lower.
    Brake pads will absolutely have a say in heat build up. We have done a ton of testing on different brake pads and have seen all sorts of temperatures under the exact same braking conditions in a lab environment.
    Same PSI, same wheel, same force being driven to the wheel, same weight on it, same braking force, and same braking duration. The only variable that changed was brake pads and between various pads we have seen differences of over 100 degrees Celsius.

    Swissstop has even done this same kind of testing and have shown the temperature differences in the same tests between the two versions.
    www.boydcycling.com Handcrafted Revolution

  10. #10
    Forever a Student
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    Good post, I was just about to say that.

    For those saying not to ride the brakes, well you obviously have never climbed a mountain of any pitch. There is no option to not ride the brakes, if you don't, you crash. If it's a road like a national park parkway or something, you'll be fine. But if it's a steep pitched switchback road, there is no choice in the matter, the brakes are on the whole way down, maybe 90% of the time minimum.

    But in general keep the carbon clinchers off of the mountains, they don't belong there. Get a pair with an alloy braking track for the pitches. And if you must run carbon clinchers please run good pads.

    I personally have descended really nasty mountains on ENVE wheels and pads without issue while those next to me had their rims explode. So the rims do have a say in the matter as well.
    use a torque wrench

  11. #11
    Pathlete and Pedalphile
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    When I received my carbon clinchers I did a comparison test with them and my aluminum clinchers (Neuvation). There is a hill near me that is a third of a mile long, averages 14% and has a max grade of a little over 20%.
    https://www.strava.com/segments/618010

    You have to ride your brakes hard all the way down as it tee's at the bottom (no where to bail out).

    I rode my aluminum clinchers down and as soon as I stopped at the bottom, I reached down and felt the brake track (front and rear) They were so hot that I couldn't keep my fingers on them.

    Next ride out I put on my carbon clinchers (same bike, same conditions) and rode the same hill.

    As soon as I stopped at the bottom, I felt the front and rear brake tracks. Barely warm.

    The only issues I have with my carbon clinchers is that they require more lever pressure to get the same braking power as the aluminum (although I can still lock up the rear easily) and on long descents when they do start to get warm, I get some squealing.
    If you try to fail, and succeed, which have you done?

  12. #12
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    Quote Originally Posted by coachboyd View Post
    Brake pads will absolutely have a say in heat build up. We have done a ton of testing on different brake pads and have seen all sorts of temperatures under the exact same braking conditions in a lab environment. ...
    Submit you results to The Physical Review and see if it gets published. I suspect issues with the testing methodology, however.
    ... 'cuz that's how I roll.

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    Quote Originally Posted by looigi View Post
    Submit you results to The Physical Review and see if it gets published. I suspect issues with the testing methodology, however.
    Aren't you ignoring the heat transfer coefficient of different materials in the brake pad?

  14. #14
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    Carbon clincher being safe for descend on hills or mountains...

    Quote Originally Posted by redondoaveb View Post
    When I received my carbon clinchers I did a comparison test with them and my aluminum clinchers (Neuvation). There is a hill near me that is a third of a mile long, averages 14% and has a max grade of a little over 20%.
    https://www.strava.com/segments/618010

    You have to ride your brakes hard all the way down as it tee's at the bottom (no where to bail out).

    I rode my aluminum clinchers down and as soon as I stopped at the bottom, I reached down and felt the brake track (front and rear) They were so hot that I couldn't keep my fingers on them.

    Next ride out I put on my carbon clinchers (same bike, same conditions) and rode the same hill.

    As soon as I stopped at the bottom, I felt the front and rear brake tracks. Barely warm.

    The only issues I have with my carbon clinchers is that they require more lever pressure to get the same braking power as the aluminum (although I can still lock up the rear easily) and on long descents when they do start to get warm, I get some squealing.
    Yeah, well all that heat has to go somewhere, like into the brake pads and tires and tubes.

    http://velonews.competitor.com/2013/...lincher_277711
    Last edited by mfdemicco; 02-09-2015 at 05:57 PM.

  15. #15
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    I live in Utah with mountain descents all around. I ride both Zipp's and Enve's. I've never had a problem with either pair when descending. For reference, I'm 170 lbs.

    Your results may vary....

  16. #16
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    Quote Originally Posted by mfdemicco View Post
    Yeah, well all that heat has to go somewhere, like into the brake pads and tires and tubes.

    The Torqued Wrench: Taking on the carbon clincher - VeloNews.com
    Yeah, well, you don't think the heat from the aluminum brake track that is too hot to touch isn't doing the same thing?
    If you try to fail, and succeed, which have you done?

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    Quote Originally Posted by deviousalex View Post
    Aren't you ignoring the heat transfer coefficient of different materials in the brake pad?
    I think so, and there is a diffrence between heat dissipated and temperature. Boyd is using the word "heat" but is measuring temperature. Still, I think his point is valid if the rim temperature is lower with the black pads. I'm not a physicist and could be wrong.

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    Carbon clincher being safe for descend on hills or mountains...

    Quote Originally Posted by redondoaveb View Post
    Yeah, well, you don't think the heat from the aluminum brake track that is too hot to touch isn't doing the same thing?
    No, the heat is being conducted away by the rim and cooled by the air over a wide area.

  19. #19
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    Quote Originally Posted by mfdemicco View Post
    No, the heat is being conducted away by the rim and cooled by the air over a wide area.
    If the outside of the aluminum brake track (which is only a couple of mm's thick) is too hot to touch then I've got to believe the inside of this this piece of aluminum is just as hot on a descent. How can the inside be getting cooled and the outside is too hot to touch. I believe the outside would get cooled first since it's exposed to the air.
    If you try to fail, and succeed, which have you done?

  20. #20
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    Quote Originally Posted by redondoaveb View Post
    If the outside of the aluminum brake track is too hot to touch...
    Not to mention the epoxy in the all carbon matrix VS the mechanical bond of the AL Brake track..

    Which has better ability not to melt I wonder...
    Quote Originally Posted by Robt57/Me!
    Everything you read that I post is just '1' guy's opinion, try to sort it all out best you can. ;) I will try to add value in my posts, if I miss the mark please let me know using a little decorum.

  21. #21
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    Quote Originally Posted by MMsRepBike View Post
    Good post, I was just about to say that.

    For those saying not to ride the brakes, well you obviously have never climbed a mountain of any pitch. There is no option to not ride the brakes, if you don't, you crash. If it's a road like a national park parkway or something, you'll be fine. But if it's a steep pitched switchback road, there is no choice in the matter, the brakes are on the whole way down, maybe 90% of the time minimum.

    But in general keep the carbon clinchers off of the mountains, they don't belong there. Get a pair with an alloy braking track for the pitches. And if you must run carbon clinchers please run good pads.

    I personally have descended really nasty mountains on ENVE wheels and pads without issue while those next to me had their rims explode. So the rims do have a say in the matter as well.


    Yeah maybe if you're coming down the side of Mt Everest

    Learn how to descend and grow some balls and you don't need to ride the brakes 90% of the time.





    .

  22. #22
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    Carbon clincher being safe for descend on hills or mountains...

    Quote Originally Posted by redondoaveb View Post
    If the outside of the aluminum brake track (which is only a couple of mm's thick) is too hot to touch then I've got to believe the inside of this this piece of aluminum is just as hot on a descent. How can the inside be getting cooled and the outside is too hot to touch. I believe the outside would get cooled first since it's exposed to the air.
    Yes you're right. But the carbon fiber should have been hotter than the aluminum since the Al conducts heat much better than carbon fiber. Can't explain that other than you didn't do a controlled experiment.

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    Quote Originally Posted by MMsRepBike View Post
    Good post, I was just about to say that.

    For those saying not to ride the brakes, well you obviously have never climbed a mountain of any pitch. There is no option to not ride the brakes, if you don't, you crash. If it's a road like a national park parkway or something, you'll be fine. But if it's a steep pitched switchback road, there is no choice in the matter, the brakes are on the whole way down, maybe 90% of the time minimum.

    But in general keep the carbon clinchers off of the mountains, they don't belong there. Get a pair with an alloy braking track for the pitches. And if you must run carbon clinchers please run good pads.

    I personally have descended really nasty mountains on ENVE wheels and pads without issue while those next to me had their rims explode. So the rims do have a say in the matter as well.
    Damn, if you are on the brakes 90% of the time downhill just remember one thing; "Slower Traffic Keep Right".

  24. #24
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    I was on my Enve's during the Levi's Gran Fondo.. the issue was not me so much but all the traffic. I actually stopped for a few minutes and let it clear out and passed them all again on the incline...obviously safer. I got caught behind a wreck that closed down the road for like nearly an hour.. so that pretty much guaranteed a larger then normal group on one of the nastier descents. = no fun.

  25. #25
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    Quote Originally Posted by 2Slo4U View Post
    I live in Utah with mountain descents all around. I ride both Zipp's and Enve's. I've never had a problem with either pair when descending. For reference, I'm 170 lbs.

    Your results may vary....
    Including Little Cottonwood?

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