Thank you for sharing this study. Threads like this draw me to ST, but are increasingly overshadowed by all the BS on the board.

Scott

Personally, I don't think that's Flo's job. I understand that engaging in any sort of testing pissing match with specific companies is a can of worms. Particularly when going up against companies with fully staffed legal and PR departments.

But we do have some independent testing of Flo vs. well-set-up benchmark wheels.

This is the *OLD* Flo 90. (full report here)

Thanks for chiming in and thanks for sharing your data! Could you tell us a little bit more about your protocol? It seems to me there was an emphasis on continuously changing the yaw vs moving to a yaw, waiting for the airflow to stabilize, measuring, moving to another yaw, etc. Please correct me if I misinterpreted that.

These kinds of statements really have me questioning the value of wind tunnel testing. If a $2K pressure sensor is needed to differentiate hundreds of grams of drag error, what's the value of wind tunnel tests if I am introducing a minimum of 'hundreds of grams' of error (e.g. ~ +/-200g = +/-20w) every time I inflate my tire with a $50 pump?

It seems like tunnel testing is a double edge sword. On the one hand, if you don't have it, you're going to get roasted. On the other hand, if you do have it and you use very sensitive controls, you may be able to tease apart differences, that unfortunately, the average rider will not be able to control for/use in a way that optimizes the advantage of that wheel.

@GreenPlease, I sure can.

To give you a bit of background. One of our colleagues entered the Ironman UK race and he wanted the fastest time possible. Not much we could do for his swimming or running but we could help him a lot on the bike. We work in Aerospace so have access to a fairly sophisticated wind tunnel. We borrowed some wheels and tested them in there along with adjusting his position (separate subject) to get him as fast as possible. This is where this data came from.

Prior to all of this we fitted out some bikes with sensors to work out where wind was coming from, it's direction and it's speed. We got several hundred rides and computed the data. From that we ran a Fast Fourier Transformation to turn the data into Ramp, Step, Sinusoidal inputs.

The flow over a bike is rarely steady state, it continuously pulses. This is combined with corrections from the rider and road furniture which alters the speed and yaw - even a passing car has an effect. The protocol you have probably seen is for 30km/h, there is another one for 50km/h. The main difference is there is much lower extremities of Yaw angle at higher speed.

You are correct in the sense the angle is changing in the tunnel. We've got the ability to do that whereas most people do not. They probably don't have as high resolution instrumentation to be able to get the numbers quickly and accurately. So what we can do in 20 minutes, may take someone a few hours at (for example) A2's wind tunnel.

As far as "Flo" Bashing goes. To be clear, I messaged Flo a few months ago and just recently informing them about possible issues with their wheels. They did not respond.

In our opinion (that's 100+ years of combined Aerodynamic experience), the Flo wheels that we tested should have better performance for their depth. They are welcome to say the tyres, pressures etc will influence the results but fundamentally we believe the profile is floored.

Thanks

Hambini

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HELLO HAMBINI FANS!!!

I find this part very intriguing, but I wonder about the magnitude of yaw and how your results are weighted. You appear to have much stronger winds (and higher yaw) than other field studies have determined are typical.

I'm guessing that in a tunnel you wouldn't find the Knot 64 wheels to be tire agnostic. I'm not sure how that would be possible.

The casing tension study is still underway. We have been studying pressure and rolling resistance extensively. That should lead to some pretty great data in the not too distant future. Data collection takes an eternity.

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Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

And this is why we haven't done it. On top of that, "IF" we show our wheels in the lead, the first thing we'll hear is "FLO weighted the test in their favor". I've said for years that it would be fun and interesting to have a list of companies send a representative to the same tunnel and have a shootout. I think that's the only way to make people believe your results. But do you think companies will agree to that? Not a chance. We tried to have people come together to develop a collective testing protocol and even that was too risky for most.

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Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

You'll never satisfy the Slowtwitch internet aero experts so I wouldn't worry about them.

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Relative to other rim profiles.

For the last 7 years, many times per day, I am asked the following questions.

1. What wheels should I buy?
2. How do your wheels compare to "some other brand?"

Here's my best answer.


Zipp, Enve, FLO, Hed, etc., all make really REALLY good wheels. Going from your stock training wheels to race wheels from any of the aforementioned brands will give you MOST of your advantage. After that, the performance difference gets much smaller. Let me explain.


Gear changes can without a doubt give you an advantage, but I think there are two categories of advantages. Certain gear changes give you large magnitude advantages, and others give you small magnitude advantages. Here are some examples of each.


Large Magnitude: Switching from a Mavic Open Pro wheelset to a FLO 60/90 in Kona will save you about 6 minutes and 20 seconds.
Small Magnitude: Switching from a FLO 60/90 to a FLO 90/90 is worth 1 second.


Large Magnitude: Using Gatorskins for an Ironman will cost you about 7 minutes vs. a tire with low rolling resistance.
Small Magnitude: The difference between two tires with low rolling resistance over an ironman... seconds.


When people start comparing Enve and Zipp—or any brands—I think it's important to realize that this is a small magnitude difference. For most people, large magnitude advantages should be the main priority. Here are a few examples.

• Get in shape. None of this matters if you're out of shape.
• Get a good aero fit.
• Get race wheels.
• Use good tires.

After the large magnitude changes are made, it's hard to say that there is a BEST. If two people spent a month in a wind tunnel finding the best solution for them, I could almost guarantee you that those two people will end up with different bikes, helmets etc. Why? Because they have different bodies. The shape of one athlete's legs may interact better with a FLO wheel and Conti tires than an Enve wheel with Michelin tires. Or vice versa. Also, If one particular frame is faster than another, but you can fit yourself on the frame in a position that allows you to produce optimal power, you probably shouldn't buy that frame.


Aside from aerodynamic performance, there are other things to consider when spending thousands of dollars for bicycle wheels.

1. Is customer service important to you? If brand A has terrible customer service, and brand B has excellent customer service, you should probably buy from brand B. Even if some guy on a forum said brand B is 1 watt slower than brand A. For example, my cell phone number is on our contact page. That is very important to some people while others don't care.
2. What is your budget? If you don't have a budget, buy whatever you want. If you do have a budget and your team gets a sweet deal on Enve wheels, then you should probably buy Enve wheels.
3. What do you want? (more for those without a budget) I just built a mountain bike. I had to decide what groupset I wanted. XO1 or XX1. I don't need XX1. X01 is an amazing groupset, and I'm likely never EVER going to see any difference by using XX1. I'd also tell all of my friends and customers to go with X01. What did I buy? XX1. Why? Because I wanted it. It's that simple. I know it really won't help me go any faster, or shift better, but I wanted the best, so I bought it, and it made me happy.

At the end of the day, make smart large magnitude choices. If you want to make small magnitude changes, you'll need to do a lot more work AND know that your small magnitude changes will likely be different than some guy on this forum. To optimize small magnitude changes, you'll need to visit a guy like Jim Manton (on this thread) or a wind tunnel.


I hope that makes sense,

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Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

You did? Where did you contact us?

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Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

“ fundamentally we believe the profile is floored“

Can you expand on the comment above? I’m not sure what you mean by “floored’?

Thanks for the study and for participating in this thread.

Scott

Fair enough. Thanks for your reply.

Edit; well said regarding large/small magnitude decisions.

Scott

that's when you just say "f*** it."

It looks like the wheel profile has been designed by an aero consultant that has been asked to make a wheel through very specific steady state conditions. Probably 50km/h <6 deg yaw. Air doesn't behave like that so when tested against real conditions the wheels perform poorly. If you peturb the bike and rider (ie simulate rocking) which is what most people do when they ride a bike, the airflow breaks away. It then reattaches moments later. The rocking is most noticeable when people go up a hill, they do it on the flat but it's not so visible.

Floored in this context - there is a design fault or poor design. I don't know the background behind the design of these wheels but it looks like there has been an over reliance on CFD and the boundary conditions have been so specific, the wheel really only operates well in those conditions.

Thanks

Hambini

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HELLO HAMBINI FANS!!!

@Chris Flo Cycling

Check your twitter account.

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HELLO HAMBINI FANS!!!

Flawed.

Apologies you are right it should be flawed. Sorry I'm not a native English speaker.

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HELLO HAMBINI FANS!!!

Got it, thanks. I appreciate the explanation.

Scott

This whole thing makes a compelling argument for the Speed Concept, assuming the Aeolus wheel testing so well here was specifcally designed for that frame?

Scott

You know, it's an interesting time we are in currently. I used to be Chief Aero Anal of my own setup. Lots of personal testing, for fun testing, etc. Different tires for different courses, etc. Multiple aero helmets. Going down the rabbit hole of everything adding up to a hopefully "most aero award" at a race in terms of watts:mph

But when you read threads like this, it just makes me feel like it's SO STUPID. It's totally not worth the time investment and financial investment that it requires for 99.8% of age group athletes. Hell, even most of the pros could do with less over analysis.

So now it's more - for me anyway - just buy what you want and make sound decisions about it and don't buy into all this lame ass paralysis by analysis aero shit.

/rant

I hear you.

That is basically what Chris said above in the context of large magnitude decisions. Make smart choices there and get on with The Work.

Scott

Yeah, I’ve come to that realization lately as well. Spending time reading and testing and analyzing to get the last few watts. Starts to take the fun out of why I started tri 10+ years ago. Hit the major stuff and don’t worry about the 0.5%.

Most (all?) of the time that last 3 Watts isn’t going to make a difference place wise for me. This coming from someone who missed Kona by 68 seconds. It wasn’t not having the perfect wheel/tire/pressure combo, it was screwing up nutrition and hydration having to walk too much on the marathon. Spent too much focus and time chasing seconds and not enough doing things that cost me minutes

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Matt

If someone creates a Triathlon Psalms, this should be in it.

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Jim Manton / ERO Sports