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PostPosted: Thu Dec 14, 2017 4:16 am 
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Posts: 30
This is a great discussion, guys, thank you for the dialogue! I'm happy to clear up a few of these questions.

First, a realistic test would absolutely be conducted with intervals, cooling periods, speed variance, caliper force variance, etc. We mimic real world conditions in our internal prototype testing. That is how we first developed these rims! For this test, however, we simply wanted to design a protocol that would allow us to directly compare the failure modes and properties of carbon clinchers. Nothing more, nothing less. You can interpret the results however you wish. For us, we have found that the results are directly proportional to the long term durability of the composite. You probably won't brake for 5min down a steep hill during your first ride on some new wheels. That's unlikely. But you may reach the resin glass temperature for 5 seconds ten times per week for many years. Cyclical loading of the resin will respond just like cyclical loading of any material - it begins to break down. The rim will slowly start to deform and pulsate under braking, and will eventually fail if it isn't caught. That's how most rim failures occur. The goal of our new rim project, and the test, was to see how we would compare with our competitors in overall durability and create a product that would dissipate enough heat every day to keep the resin from seeing long term effects.

Of course there are metrics that people still want to see. We can only test so many variables in one study, but we will have more tests to present to you guys soon! The more data the better. But it's important to note that the heat buildup in the Alto rim was dissipated faster due to the resin properties, not a lack of friction. This can be seen in the phase 2 test, where the total load and friction were greater than other rims (i.e slower rim speed before pad glassing) but the temperature remained lower. Also keep in mind that the total amount of energy into each rim (for phase 1) was identical, as it includes the kinetic energy of the spinning wheel. The equation would include the motor input, caliper force, pad/rim friction, and rim speed. A rim that sees more friction due to the textured track (like Enve) will spin slower, and the energy dissipated by the rim will be identical because it must reach a 1200W equilibrium. The amount of that energy converted to heat has to do with the properties of the composite and the resin.

I hope that helps to clear up some questions, although it may create more! Either way, I'll check in and respond as much as possible! Thanks again for the discussion, that's what it's all about.


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PostPosted: Thu Dec 14, 2017 5:15 am 
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Quick question, is your brake track smooth or textured?

Thanks

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Posted: Thu Dec 14, 2017 5:15 am 


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PostPosted: Thu Dec 14, 2017 7:36 am 
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This test is discussed on the cyclingtips podcast:

https://cyclingtips.com/2017/12/cycling ... tive-mean/

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PostPosted: Thu Dec 14, 2017 11:17 am 
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AJS914 wrote:
This test is discussed on the cyclingtips podcast:

https://cyclingtips.com/2017/12/cycling ... tive-mean/
Really disappointed with the answers from the ENVE and Mavic reps. They both complain that braking effectiveness is not equal, but then why did the Alto survive the 9lbs test with the wheel being slowed under braking to 19.5mph just like the best of the rest?

A lot of stammering and stuttering. They really struggled to say rim-brake carbon clinchers are safe to ride, and that’s the problem James Huang was complaining about.


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PostPosted: Thu Dec 14, 2017 1:59 pm 
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Posts: 348
BobbySweeting wrote:
Also keep in mind that the total amount of energy into each rim (for phase 1) was identical, as it includes the kinetic energy of the spinning wheel. The equation would include the motor input, caliper force, pad/rim friction, and rim speed. A rim that sees more friction due to the textured track (like Enve) will spin slower, and the energy dissipated by the rim will be identical because it must reach a 1200W equilibrium. The amount of that energy converted to heat has to do with the properties of the composite and the resin.
How is this relevant? Total energy is meaningless if one rim absorbs less heat because less heat is produced due to a lower coefficient of friction.

By the way, what is the strategy Alto rims use to last longer under braking? Do they heat up less/dissipate heat faster, or are they able to withstand higher temperatures? A combination of both?


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PostPosted: Thu Dec 14, 2017 3:24 pm 
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BobbySweeting wrote:
The amount of that energy converted to heat has to do with the properties of the composite and the resin.

I hope that helps to clear up some questions, although it may create more! Either way, I'll check in and respond as much as possible! Thanks again for the discussion, that's what it's all about.
What resin are you using and what is its tg and k (thermal conductivity coefficient)? If, as you claim, are getting just as much heat energy into your wheels as your competitors, then you must have a superior resin, either doped or higher tg. Since the temperature is staying down on your wheels then you must have superior conductivity or you are not getting as much heat energy into your wheels, so you must have a higher k. I'm not convinced the test is equitable but am willing to be convinced otherwise.


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PostPosted: Thu Dec 14, 2017 3:28 pm 
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Joined: Fri Dec 15, 2006 7:45 pm
Posts: 4443
Location: Natovi Landing
BobbySweeting wrote:
This is a great discussion, guys, thank you for the dialogue! I'm happy to clear up a few of these questions.

First, a realistic test would absolutely be conducted with intervals, cooling periods, speed variance, caliper force variance, etc. We mimic real world conditions in our internal prototype testing. That is how we first developed these rims! For this test, however, we simply wanted to design a protocol that would allow us to directly compare the failure modes and properties of carbon clinchers. Nothing more, nothing less. You can interpret the results however you wish. For us, we have found that the results are directly proportional to the long term durability of the composite. You probably won't brake for 5min down a steep hill during your first ride on some new wheels. That's unlikely. But you may reach the resin glass temperature for 5 seconds ten times per week for many years. Cyclical loading of the resin will respond just like cyclical loading of any material - it begins to break down. The rim will slowly start to deform and pulsate under braking, and will eventually fail if it isn't caught. That's how most rim failures occur. The goal of our new rim project, and the test, was to see how we would compare with our competitors in overall durability and create a product that would dissipate enough heat every day to keep the resin from seeing long term effects.

Of course there are metrics that people still want to see. We can only test so many variables in one study, but we will have more tests to present to you guys soon! The more data the better. But it's important to note that the heat buildup in the Alto rim was dissipated faster due to the resin properties, not a lack of friction. This can be seen in the phase 2 test, where the total load and friction were greater than other rims (i.e slower rim speed before pad glassing) but the temperature remained lower. Also keep in mind that the total amount of energy into each rim (for phase 1) was identical, as it includes the kinetic energy of the spinning wheel. The equation would include the motor input, caliper force, pad/rim friction, and rim speed. A rim that sees more friction due to the textured track (like Enve) will spin slower, and the energy dissipated by the rim will be identical because it must reach a 1200W equilibrium. The amount of that energy converted to heat has to do with the properties of the composite and the resin.

I hope that helps to clear up some questions, although it may create more! Either way, I'll check in and respond as much as possible! Thanks again for the discussion, that's what it's all about.
As others have said, you need to re-do the test using manufacturer's recommended pads. And if the price of durability/heat resistance for some rim + pad combinations is inferior braking performance then you need to measure that. It's disingenuous to call out a "failing" of a "system" that isn't in fact the manufacturer's recommended system at all.

If you do this testing, and your rim is as/more durable as others', and you have better braking performance, then you have a real winner

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PostPosted: Thu Dec 14, 2017 3:56 pm 
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Joined: Tue Dec 05, 2017 12:09 am
Posts: 9
What I really want to know is why you claim the rim is 52mm when it's actually 50mm. I mean, I think I have a pretty good idea and I brought it up in a previous form.

I took the rim profile images from your site, and the new Pacenti rim profile from their site. I put them side by side without changing the ratio of the image at all!
Then I overlayed one on top of the other. It's pretty clear that you are both using the same rim profile image.
I remember when you first had your alloy wheels you bought the alloy rims from Pacenti but claimed they were your own design even though they were clearly the Pacenti rim.

You claimed the rims are different depth, widths, and shapes. . .but clearly they are not.
In talking with somebody who has the rims we were able to clearly measure the rim is not 52mm deep as you claim. It is 50mm deep!

Image


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PostPosted: Thu Dec 14, 2017 4:43 pm 
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Joined: Thu Mar 28, 2013 4:42 pm
Posts: 909
Location: Pa USA
:popcorn:


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PostPosted: Thu Dec 14, 2017 5:28 pm 
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Joined: Mon Oct 30, 2017 11:27 pm
Posts: 48
wrote:
I am for everyone making the switch to disc braking.
WHY??? I love my disc on my MTB but I rarely ride my road bike in the rain (live in SoCal), am most interested in being KOM on the ascent, don't mind taking it easy on the decent, and as a born again WW am counting grams. My road bike weighs in at under 14lbs, and I have yet to see a disc bike come close (that I could afford). So practically speaking, what am I missing, other than extra weight, by having rim brakes?


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PostPosted: Thu Dec 14, 2017 5:49 pm 
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Posts: 2692
Location: Islip, NY
Someone tell Pacenti not to put his Alto rims in the dryer. They shrink!

Sent from my SM-G950U using Tapatalk

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PostPosted: Thu Dec 14, 2017 8:54 pm 
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Joined: Tue Jun 13, 2017 9:57 pm
Posts: 20
Has there ever in WW history been a successful post by a manufacturer or subject of an article


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PostPosted: Thu Dec 14, 2017 9:29 pm 
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Joined: Mon Oct 30, 2017 11:27 pm
Posts: 48
wrote:
But it's important to note that the heat buildup in the Alto rim was dissipated faster due to the resin properties, not a lack of friction.
Can you describe why/how? I could see (and want) a resin that withstands heat better but one that is significantly more conductive? Really? Area is typically the bigest factor in the ability to dissipate heat (think all those little fins on a heat sink to increase surface area), but few materials have such superior thermal conductivity to make a big difference on small surface areas (gold plated rims anyone?)

So are you sure that you rims are more thermally conductive or is it that your resin can withstand higher temps.


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PostPosted: Thu Dec 14, 2017 10:02 pm 
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Joined: Tue Jan 28, 2014 6:52 pm
Posts: 1637
TobinHatesYou wrote:
AJS914 wrote:
This test is discussed on the cyclingtips podcast:

https://cyclingtips.com/2017/12/cycling ... tive-mean/
Really disappointed with the answers from the ENVE and Mavic reps. They both complain that braking effectiveness is not equal, but then why did the Alto survive the 9lbs test with the wheel being slowed under braking to 19.5mph just like the best of the rest?

A lot of stammering and stuttering. They really struggled to say rim-brake carbon clinchers are safe to ride, and that’s the problem James Huang was complaining about.

I agree with regards to the vague answers from Mavic and Enve. They obviously won't admit that carbon clinchers just aren't as bullet proof as aluminum rims.

They explained why the Alto could survive the test - less friction.

Here is the James Huang article:

https://cyclingtips.com/2017/12/carbon-clincher-safety/

In that article, it does say that the Alto rim suffered some delamination.

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Posted: Thu Dec 14, 2017 10:02 pm 


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PostPosted: Thu Dec 14, 2017 10:14 pm 
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Joined: Mon Jul 24, 2017 12:02 pm
Posts: 559
There’s just as much friction in the 9lbs test with Alto’s rim vs the 7lbs test with the other rims.


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