Hmmm...could these test results be explained by the Alto rims having a lower friction coefficient than the others? If so, that wouldn't be too good for braking performance, now would it? ;-)

Doing a test like this without measuring braking torque is a bit of a "mis-fire" IMHO...

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Doing a test that is not similar to real world conditions and using it as a marketing exercise is annoying.

This test was designed to destroy all rims but one. Re-do the test with real world scenarios and I bet the results change.

You are correct that a rim with less bite on the pads will take longer to slow down.

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Not using rim specific pads either. Sure, sell it as "consistent testing", but still a little sneaky to not use the appropriate pads for each wheel.

Once the brakes are applied, with that 1200W motor they'll keep a constant speed (i.e. won't continue to slow down). However, the ones with the lowest friction coefficient, will be turning at a higher speed because they are converting less power into heat.

I guess one way to quantify this would be to monitor the steady-state wheel speed during the testing...

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http://bikeblather.blogspot.com/

If you watch the video, some of the wheels start bouncing around.

This is nothing more than a marketing exercise. This reminds of the time Alto said "we did work in the wind tunnel" by having their athletes send them their wind tunnel data from testing. No one from Alto was actually there at the tunnels.

Let's see if they respond to this thread.

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You are as ever correct. If they were making Teflon coated rims, they’d do well in this test, but not so well in a test of stopping, which is a think that brakes are sometime used for.

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Developing aero, fit and other fun stuff at Red is Faster

If it starts raining, I bet these Alto wheels are the worst when it comes to stopping. You need friction on the brake track to stop. You need to have a rougher surface to generate more friction and heat. Then you need a resin that can handle it.

They are basically claiming they don't have a resin that can handle the heat load so they have created a wheel that takes longer to stop.

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I took a quick scan through the video and luckily they show a real-time monitor of wheel speed. And, for an equivalent brake load, the Alto wheels were running a full 1mph faster at initial application...and then started running even faster as the test went on (meaning the friction coefficient was dropping even further).

That's pretty much the complete opposite behavior of most of the other rims :-/

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this has got to be the DUMBEST fucking "scientific study" i have ever seen in the triathlon space.

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@adamwfurlong

Worth noting; I'm guessing it didn't take you any longer than it took me to recognize this rather large issue with the test procedure, and it's not even raised in the article.

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That's terrifying. So down a long decent, your brakes will get worse the longer you go?

Hey guys! I'm happy to answer any and all questions about our methodology. There are 100 ways to conduct this test, and I can explain why we did what we did.

Regarding brake pad selection: The brake pad variable must be controlled in order to follow a true scientific method. There is no chemical reaction happening between the pad and rim, it is simply friction that is causing heat. So a lighter density Enve pad may have allowed the Enve to run 10% longer in the test, but an Enve pad would have allowed every other rim to run 10% longer as well. What we didn't want to do was have a different pad on each rim. If we ran a cheap ebay rim with a cork pad and it lasted 10 minutes, would you believe that it was a higher quality than a Zipp rim? Would the result mean anything at all? So we had to use the same pad on every rim, and the choice of which pad to use is irrelevant. It's also important to note that you can run any carbon brake pad on our new 2018 rims with zero risk and without voiding the 5 year warranty. It isn't possible to damage them in any way.

The wheel speed in our tests varies from roughly 19.5-20.2mph in phase 1 to 19.3-19.8mph in phase 2. This is prior to the pads glossing over, which happened as a result of being exposed to sustained heat. This is a function of the pad and not the rim. Any rim that would have lasted through phase 1 would have seen the same phenomenon with speed increasing throughout the test, but none got to that point.

The power input (1200 watts) is the power required for a 180lbs rider to go from 20mph to 0mph in three seconds. We wanted to make this a realistic input power, but also realized that the power input would not effect the results in any way (other than the length of the video). It could be 400 watts or 4000 watts, the failure times would be directly proportional.

We did notice that our rims ran about 0.5mph faster than some of our competitors early on in the test before the pads glazed over. This was well noted! But keep in mind that going from 7lbs to 9lbs brought us down below the speed of other brands. The average grip strength of an adult is roughly 100lbs, so a 2lbs different to alter stopping power by 0.5mph is very negligible. This was also not an accurate test of stopping power because we didn't set it up that way (would've been better to control speed and let motor amperage vary), but it's a good takeaway from the test and something that we'll keep looking at!

Someone mentioned wheels bouncing around... the jig hit resonance a few times and it took time to quiet down. That's normal for anything with a frequency, it's unavoidable but also doesn't effect results in any way.

This test was designed to create a standard for carbon clinchers, in conjunction with Spark Wheel Works. It was NOT meant to be a marketing ploy, and we didn't know what the results would be when we went into it! We told Ryan Mason to supply us with the rims, and that we'd by publishing the results regardless of how we did. We knew we had created a stellar new rim, but had no idea how we compared with our competitors. I don't think anyone had a good answer for that, so we wanted to quantify it.

Please let me know if you guys have any other questions regarding the test methods! As I said, there are a lot of ways to do this. We went with a test method that we felt would isolate the variables that we wanted to study, and I think we showed some very compelling results!

Well, all y'all brake for shit.

do you have these wheels?

i've used a variety of carbon clinchers. i have not used alto or boyd or fse from that test. the implication in mr sweeting's acknowledgement that his rims require an extra 2lbs of force to achieve the same braking output (slower rim speed) is that his rims are even worse at braking than the others.

right

So why is your 52mm rim actually only 50mm deep?
Unless my digital calipers are wrong.

The big takeaway for me was that.....those enve decals look pretty cool at speed. :)

It seems to me a fair test protocol would hold wheel speed and input watts constant while allowing braking force to vary to achieve a given wheel speed at given input watts. That would be a true test of what degree of sustained braking a given wheel could sustain (if I can safely descend a particular hill at a particular speed, this will tell me which wheel will get me down in one piece and which will fail, though it won't tell me how hard I'll have to squeeze the brakes to achieve that speed). As designed, it's impossible to differentiate the contribution of poorer braking (and reduced heat build up as a result) from the wheel's ability to handle that heat.

Even taking this flawed test protocol at face value, I'm curious whether Alto has a theory of why their wheel supposedly handles heat better. Proprietary resin formulation that handles heat better? Proprietary design that sheds heat better (perhaps an overbuilt wheel with greater safety margins)? What is it about this new rim that made them think it would be superior at handling heat and motivated this test?

Someone DM me when Jake from Enve chimes in on this one...

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Yes, there are many ways to structure the controls and variables in this test. As long as you limit the variables you will get accurate results, regardless of what you decide to measure. Allowing brake force to vary is a much more difficult procedure, which we didn't feel would offer any increased validity to the test.

We've spent the last 8 months testing various resin additives (all of which are proprietary and will not be disclosed) that would help it to flow more readily through the layup. This helps to control and dissipate heat by making a more uniform structure. Along that same though process, we experimented with filament winding the brake track as opposed to laying it up by hand with pre-preg. This gave us extremely tight compaction between the fibers, and increased tension on the fibers themselves. The resin additives (and resin Tg itself) and the filament winding process resulted in a completely heat resistant carbon clincher.

Um, no, it is absolutely not the case that "As long as you limit the variables you will get accurate results, regardless of what you try to measure." That is a remarkable statement.

I don't think you understood my comment. I'll try again. In the case of your test and your wheels' performance, how is a consumer supposed to differentiate between the possibility that 1) your wheels simply have less friction, i.e. brake less well, so at given input watts and with given brake pressure, there is less friction and hence less heat generated (others have suggested your video in fact suggests your wheels spun faster) and 2) your wheels are either produce less heat while the same amount of braking effect is generated (the physics would seem odd, I think) and/or your wheels are better able to handle a given amount of heat.

If the first possibility turns out to be the case, then in real-world use your wheels may be no safer, and possibly less safe, than your competitors. It's only if the second possibility is the case that your wheels have a safety advantage over your competitors. And it would seem to be impossible to differentiate between these two possibilities based on your test.

Assuming you have the wheel speed data, you could at least compare your wheels to wheels that exhibited the same speed at the given power input and given brake application. Perhaps you could even do a calculation to try to adjust the data around a normalized wheel speed? But I'm not convinced that's feasible.

Hope that makes more sense!

Your three main variables are wheel speed, motor power input, and brake caliper force. Two should be controlled and the third measured. Our engineers felt as though it would be most accurate and easily understood if we controlled power input and caliper force. It would have also been very difficult for us to create a setup with variable caliper loading, considering that we don't have unlimited time and budget for pressure transducers and the like, haha. My only point was that, regardless of the test setup, the results table at the end of the video will show the rims in the same order. Hopefully another brand will take all of this to heart and do their own testing with a different setup, and we'll definitely submit a rim!