Real World Aero Testing via Chung Method - Data Thread

[kgt]

There is not just one ideal position on a bike. It depends on the type of the course, it depends on the length of the course, the wind, the relief of the road, etc. etc.

[Stalkan]

But there is one ideal position when you're trying to save every last watt and produce the most speed.....but that's not the point of this exercise is it? Ryan is/was trying to determine how his bikes compare to each other. Your take away is that frames don't matter, at least not in an aero sense. Karsten's is that position is the key overriding factor. For me it's a combination of the two: a frame that's fast that puts you in the best position. Will I need to sit up when climbing, sure; will i tuck when spun out and descending, of course; when I am driving a break will I be focusing on being as aero as possible while making good power, you bet ya; and when I roll back in the line up will I sit up some to recover and relax a bit before my next pull, most definitely. None of this changes that all else being equal my Felt Aero Road is faster than my FC was, my Seven is, and probably any other number of bikes that I have the same fit on.

[RyanH]

For those that do find this interesting, I'll probably acquire an S5 to test and I'll make sure to do it on an identical basis. I'll move eTap to the Fuji later, get a few baseline runs then move the bars and eTap over to the S5. That way we're dealing with everything the same.

I'd do this with the Foil but I don't think a -17 1.25 stem exists, correct? I have a -12 specialized adjustable but it's 1.3" without the adjustment shim. Any suggestions on shimming that?

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[emcardle]

You can get a giant -20 1.25 stem. Have a look at ebay.

[RyanH]

I saw that but I think they max out at 100mm, correct?

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[emcardle]

Ahh, didn't know that... maybe a Pro stem in -10 would be the lowest possible?

[RyanH]

The Pro 7S is my lowest obtainable 1.25 stem. It would put my drop about 1mm higher than the Fuji.

I have the Specialized Pro Set stem which measures 1.3 and has 12d (they have a 17d option too). I found that a Sapporo can is the right thickness to shim it, but is that safe? I've heard of people using cans to shim seatposts but steerer seems like a whole different beast.

[jekyll man]

Ritchey do a -17 1.25" stem, could be a bit hard to get hold of though.

[RyanH]

Yeah, they used to make them for Canyon but they are out of production and unobtainable as far as I can tell.

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[KWalker]

My point is that anyone reading the thread might find it neat that you're testing, but as I've made the point quite a few times you haven't even bothered to optimize the key variable so the results really aren't that spectacular or interesting. It's a good how-to though on how to Chung test. It's hard for people to get super interested in results when the OP is clearly seeing the forest for the trees and is seeing similar results most likely because they're not all that aero in the first place and are trying to optimize the part of the system that is much further down the chain in terms of cda impact. It's helpful to know tho that if someone doesn't have their body/helmet and kit dialed, that the frame probably won't matter as much, however, when most people are buying a new bike that won't likely sway them to or from a purchase. I'm all for distilling knowledge, but it's better to stun with brilliance than baffle with b/s or too much info.

I'm a bit in disbelief that you can go from cat 1 threshold to not being able to hold 1200VAM for a few minutes regardless, but that's another topic. Even if you were 10% off your peak power figures, the pack speed from the race was such that ya should've caught on. Considering that course has a downhill and flat section after, that's where having a good position or much better than the numbers in this thread would make or break a race. So having a good bike fit that cost a few hundred would make or break more than all of this stuff.

What I think would be more neat is if you altered your body position and Chung tested it as well as perhaps did some trainer intervals to determine efficiency, and then worked in each piece of the aero puzzle and got the entire package more aero.

[RyanH]

...I'm a bit in disbelief that you can go from cat 1 threshold to not being able to hold 1200VAM for a few minutes regardless, but that's another topic. Even if you were 10% off your peak power figures, the pack speed from the race was such that ya should've caught on. Considering that course has a downhill and flat section after, that's where having a good position or much better than the numbers in this thread would make or break a race. So having a good bike fit that cost a few hundred would make or break more than all of this stuff.

I don't know why I'm bothering explaining but here it goes anyway. I spent a little over 5 minutes at an average of 353w (@70kg - that was an average with coasting). After hitting 190bpm (my point of no return HR) and realizing that I misjudged where the climb ended, I knew I was in deep crap. I gave it a whirl again anyway at the last leg of the climb and for a minute I held 356w but I was toast. Had I thought that it was remotely possible the pack would putz around again I would have dug deep, but I mean, c'mon, WTF is a race finishing the flat part at cruising pace, especially with the threat of bigger sprinter guys latching back on? So, I brought it down to 280w for the last 2.5 minutes. After I finished the descent and over the "poor me", I dug back in to TT back. A group of 4 guys caught me about 4 minutes into my solo effort. We averaged 28.7 mph for the remaining 7 miles. We still dropped one guy, and one of the two teammates couldn't pull at more than 26mph. So sure, it's obvious that my bike fit was the culprit and I should have been able to solo back in without breaking a sweat...

Oh, and my zone distribution? Of the 3:12, 1:40 in Z1 and 27 minutes above 360w (Z6/Z7). Last race I spent that much time in anaerobic land I got 8th.

Last thing, and after I say this I don't really care to engage in this conversation further since you refuse to read and comprehend what I'm writing. This thread started because I purchased an aero bike and wanted to see how it stacked up to the bike(s) it was replacing: the Cervelo and the Fuji. It was also not intended to be "my own" thread. I was hoping other people would partake as well and provide data. This forum **had** a reputation for data and we've drifted from that. This was an effort to reignite that and provide something unique to our forum. Had I not done this testing, I would have been like most other people and went "ooh yay, my new aero bike is like totally 2mph faster, all my Strava times say so." It was not a selfish endeavor to optimize my position and publish my results to the world for their praise. Optimizing your position is a very valid point and in retrospect, should have been done first, but I, like 99.8% of other people, didn't do that.

[Marin]

It's one of the best and most interesting theads of the year with tons of info for people interested in this topic.

I couldn't care less about the effective Cda of a Scott Foil frame since I won't ever own one (probably), but I find the protocol report, test runs and discussion very valuable.

[Sacke]

For those that do find this interesting, I'll probably acquire an S5 to test and I'll make sure to do it on an identical basis. I'll move eTap to the Fuji later, get a few baseline runs then move the bars and eTap over to the S5. That way we're dealing with everything the same.

That's awesome!

There are tons of aero-testing done in labs with controlled environments, and those numbers are widely spread already. There are also theoretically calculated real world tests (like Tour magazine's(?) 100km virtual loop, taking into consideration bike weight etc).

This thread is one of the best threads on aero testing. It is much appreciated!

[kgt]

This thread is one of the best threads on aero testing. It is much appreciated!

+10
I also think RyanH's test is much more valuable than any test done by Tour, Specialized, Cervelo or any other magazine or manufacturer that wants as to believe that they can test which frame is faster in a lab or through a simplistic computer simulation.

[KWalker]

They aren't the same kind of test. In those tests there is a static dummy used in a very controlled setting to compare frames. A Chung test can, in situations be used to do the same, but in this case is used to test an entire system.