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  1. #1
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    Alto CC52 carbon clincher wheelset

    Putting rim brake-equipped carbon clinchers to the test | Road Bike News, Reviews, and Photos

    That's pretty impressive heat resistance, wouldn't you say?

  2. #2
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    You have to choose between heat resistance and impact resistance. Sort of a sliding scale thing. That's the way it always has been anyway for carbon clinchers.

    So based on the old logic, these will then be more prone to delamination from pot hole strikes and other such impacts.
    use a torque wrench

  3. #3
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    Couldn’t have said it better than this - https://cyclingtips.com/2017/12/carbon-clincher-safety/

    IMO, CCs are just a dead end street. If that all isn’t enough for you, Toray, who makes most of the carbon that gets used in these things (they’re the T in ‘T700’ etc) just admitted to a major strength testing fudge. Nothing to do with carbon this time, but that’s the supply chain. And all that for what? There are SO MANY good alloy rims out there right now.

  4. #4
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    Just bought a set of boyd wheels.

    Wonder if that picture of the failed boyd rim was intentionally a boyd wheel.

  5. #5
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    Quote Originally Posted by crit_boy View Post
    Just bought a set of boyd wheels.

    Wonder if that picture of the failed boyd rim was intentionally a boyd wheel.
    I am drafting up my official response to the article (just got off a plane from Taiwan).

    Don't worry, you're safe and your braking power is much much better than the rim that goes forever on this flawed test.
    www.boydcycling.com Handcrafted Revolution

  6. #6
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    In the prototype testing of our own rim we found two extremely interesting bits of information: a nylon rim strip would melt, and a small tube would fail pretty quickly! So the first thing we did was develop our new high temperature tubeless tape, which has a melting point of 915ºF. That solved that issue completely. For the tubes, we saw a massive difference when we switched to a 25-32c Continental tube, as opposed to their 18-25c option. Even though we were testing with 25mm tires, the wider rims allow that tire to have an actual width around 27mm. So the 18-25c tube was too small, and the wall of the tube was failing at sustained temperatures over 200ºF. So, as two side notes for customers to take away from this test: make sure you’re using quality rim tape and that you’re using the largest tube possible for your setup! Every rim in this test used our rim tape and the same sized Conti tube, of course.
    I guess that's something worth taking from this.
    use a torque wrench

  7. #7
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    Got it, there rim did the best. Can’t imagine how that happened.

  8. #8
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    Quote Originally Posted by FeltF75rider View Post
    Got it, there rim did the best. Can’t imagine how that happened.
    There's not much trickery going on here.

    The wheel was spinning at 1200W with a constant brake force of 7lbs. There was some variability in wheel speed, ~1.5mph, with the Alto being the fastest.

    So that means there was less friction with the Black Prince pad and Alto brake track combo, but not a significant amount. The other wheels still failed in spectacular faction at 7lbs when the Alto passed easily. The test ran so long, it looks like the Black Prince pads glazed over a bit because the speed of the Alto wheel climbed from 20.5 to 21mph eventually.

    You could claim that Alto carefully picked the parameters for the test so that heat generation plus dissipation was in balance, but that's where the second pass is important. At 9lbs brake force, the wheel speed falls more in line with the other wheels and it still survived a 20 minute test.

  9. #9
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    Quote Originally Posted by ceugene View Post
    There's not much trickery going on here.
    The test procedure appears transparent & consistent. However, if I wanted to look good in this test, why not design a brake track with a very low coefficient of friction (think ice cube) when paired with Black Prince pads. Even though brake tracks should have a high CoF for braking performance, that wouldn't win this test. A low CoF would generate lower heat, last longer in the test & look like a champ.

    The guys in the URL quoted by November Dave mention the high-friction brake track on some Zipp wheels but I believe some others also use this (like Boyd) & then there's also basalt coatings which are also supposed to enhance performance (& increase friction). Whether specific rims in the test have a high-friction brake track isn't clear to me.

    In theory, I'd think lower friction would show up in higher speed, if the power to the drive motor was truly kept as a constant, but maybe I'm missing something ...?
    --
    All the best,
    Ron
    Central-Western NJ, USA

    There's nothing in the middle of the road but yellow stripes and dead armadillos.
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  10. #10
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    Quote Originally Posted by ceugene View Post
    There's not much trickery going on here.

    The wheel was spinning at 1200W with a constant brake force of 7lbs. There was some variability in wheel speed, ~1.5mph, with the Alto being the fastest.

    So that means there was less friction with the Black Prince pad and Alto brake track combo, but not a significant amount. The other wheels still failed in spectacular faction at 7lbs when the Alto passed easily. The test ran so long, it looks like the Black Prince pads glazed over a bit because the speed of the Alto wheel climbed from 20.5 to 21mph eventually.

    You could claim that Alto carefully picked the parameters for the test so that heat generation plus dissipation was in balance, but that's where the second pass is important. At 9lbs brake force, the wheel speed falls more in line with the other wheels and it still survived a 20 minute test.

    Want some credibility, don’t do the test yourself. Not That these wheels were on my radar but I can assure you they will not be now. As stated, 100 ways to do this and an unbiased party doing the testing might be #1 of 100.
    So how much more real estate will I need for these to stop me? Could be be more critical in my life or death than its ability to hold heat. 10 -15 meters? My guess is braking is far inferior and that’s the take away more than the heat issue.
    Last edited by FeltF75rider; 12-10-2017 at 08:41 AM. Reason: More thoughts on the matter.

  11. #11
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    The CC52's are only $2020 per set. I'll take three!
    Ghurarmu shirkush’ agh azgushu. Zant ya apakurizak. Gûl-n’ anakhizak.

  12. #12
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    Hey guys, thanks for the great dialogue regarding our test! I'd like to jump in to answer a few questions and offer my two cents on why we did what we did:

    As far as the test's realism goes, that is somewhat irrelevant. We wanted to create a study on resin and composite heat transfer properties, nothing more and nothing less. This is why we had to use one type of brake pad for every rim, as opposed to brand specific pads. If we purchased a cheap rim from ebay that comes with cork pads, it may run for 10 minutes on this test. The Enve may run for 8 minutes with Enve pads. What could you then conclude regarding the composite structures? Does the ebay rim have better heat transfer capabilities than Enve? It's impossible to tell, as there would be too many variables.

    Also regarding the realism of the test: This is an accelerated destruction test, which is very common in every engineering industry. I'm sure that you read my example that was given by the marine engineer, regarding corrosion resistance of bolts and how they test for it. They simply place the bolts in cups of salt water. Nobody is arguing that the bolts on a boat will be submerged underwater for eternity. But you can use the results to say "the bolt that prevented oxidation longest in the cup of salt water will prevent oxidation longest while on the boat." It's easier to perform that test than to spray the bolts with salt water for 10 minutes every day for a year, and the results will be the same. That's the point of an accelerated destruction test -- the rims that have the greatest resistance to heat fatigue will show the greatest durability to heat fatigue over many years of use. As long as the results are directly proportional and can be extrapolated, that is good reason to perform the test.

    Keep in mind that Alto offers unlimited rider weight, a 5 year warranty, and the allowable use of any carbon brake pad. We are the only brand in the world to offer this combination, and it means that we have to test to very extreme scenarios. If a 140kg rider decides to descend Mt. Ventoux and only use his rear brake, we have to ensure that he is safe. That calculation would look something like this: For a 140kg rider descending a 12% grade at 50km/hr: Fb (brake force) = Fg (net gravitational force) = (m)(g)sin(theta) at constant speed. For a 12% gradient (7 degrees) and 140kg rider, this is 167.38 N. At 50km/hr, Power = Fv = (167.38N)(13.89 m/s) = 2324.9 Watts (1162.5 watts per rim). This does not take wind resistance into account, but if you consider any factor of safety then you can see why survival at 1200W is necessary for us at Alto.

    Some of you noticed that the Alto wheel begins to speed up throughout both tests (phase 1 and 2). This is due to pad glazing, which occurs after the pad reaches high temperatures for a sustained period of time. It is a property of the pad and will occur on every rim given enough time. You can see it beginning on the Zipp and Enve tests, for example. Also consider that the Phase 2 Alto test had the rim running slower (19.3mph) than any rim in the test, and therefore with more friction force. However, it still ran for 20min at lower temperatures due to the improved conductivity of the resin and its ability to act efficiently as a heat sink. Also keep in mind that the average adult has a grip strength of 100 pounds. So these minor differences in braking power can be measured in the lab, but wouldn't be noticeable to any rider out on the road. Our customers tend to prefer Alto's braking power simply because there is no pulsation from overheating and therefore the deceleration feels much more consistent. But remember that, because we didn't use brand specific pads, braking power is not a proper/accurate takeaway from this test. Some rims would do much better or much worse with their own pads when it comes to stopping power, and a different protocol would be required to test for that.

    A few of our competitors gave us credit for creating a resin with such excellent heat transfer properties, but figured that it would make the rim very brittle in impact. We didn't want to simply tell people that this wasn't the case, we wanted to show them. That's more our style, obviously. So we recently conducted an impact test that you can see here: https://www.youtube.com/watch?v=DOW092uOpLg&t=31s

    I don't frequent the forums a ton, but I do want to answer any other questions that you guys may have. Please feel free to reach out to us through the contact page of the Alto website, and we'll get back to you straight away!

    Thank you!
    Bobby

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