Real World Aero Testing via Chung Method - Data Thread

[Stalkan]

@KWalker, sorry I'm having a hard time believing that.

I'm with you @ryanH. My baseline on my DA was .225....now that's a good way off from .25, but i'd love to see the guys on road bikes that are getting that close to my baseline position.....

[KarlC]

@KWalker, sorry I'm having a hard time believing that. Attached is a screen shot of Chris @ Specialized in the wind tunnel in the drops position which netted him a CdA of around 0.32. He looks pretty aero to me. Would you care to share some data to substantiate that?

If I remember, I'll have someone take a picture of me riding on the weekend but I'm 5'9 on a small frame (S/M in Fuji, 51 in Cervelo and 52 in Scott). I normally run a slammed 110mm -17 stem but tested a 125mm -17 on the Fuji today. Bars are 38cm CTC at the hoods. Not exactly a cafe cruiser position, but hey, if there's room to optimize my position and get it down to 0.25 to 0.27 on the hoods then I'm all ears. At 0.25 with a FTP of 300w, I could hold, theoretically, 26.7 mph on the hoods!

Correct me if my thinking is wrong but if Chris hands where on the hoods with his arm bent at 90 he would be lower, and his back would be flatter.

Likely he would be more areo and have a lower CdA yes ?

[Grill]

A really good road bike position is in the range of .260m^2. The best bike positions are <.180m^2 (I know of a few below .170m^2)

[RyanH]

@KarlC, I read somewhere that whether you do the hands on the hoods with arms bent at 90 or in the drops, it doesn't make as much of a difference as long as your back is flat. With that being said, yeah, he'd be lower and should have a lower CdA but for illustrative purposes in using that image, I'm not doing my testing in an aggressive position, just my regular riding on the hoods position.

Hopefully I'll get a no wind day before I leave for my business trip on Tuesday. My gut is telling me that the longer stem might push my CdA to sub 0.3 on the Fuji.

[Stalkan]

A really good road bike position is in the range of .260m^2. The best bike positions are <.180m^2 (I know of a few below .170m^2)

I am assuming these are all at 0º? If so, I'd love it if I could hit those numbers on my Time Trial rig let alone my road bike. I'm curious, though, as to the size of the individual that is .260 and more so of those that are sub .180.

[KarlC]

My biggest issue is getting motivated to ride early in the morning. Training in the afternoon is hit or miss since I can be zapped by work and zero desire to push myself on the bike. Through fall and winter, I'll begin the same training plan as last year which will overlap with the testing. I think Chung method model should be flexible enough to accommodate non sprinting intervals.

Kwalker, curious what CdA numbers you have seen with people riding on the hoods? I thought the low 0.3's was a fairly good number considering non optimized TT positions begin around 0.27. Specialized did their WIN tunnel testing on positions and the faux aero was 0.27 and drops were 0.32 so me posting up 0.31 to 0.32 on the hoods, not sure how you're coming to the conclusion I'm giving up a lot on position. I am going to test a longer stem and see what the effects are as well as see if I can cope with the extra length.

I do agree with others that so far the results are not very comparable as my position is changing between bikes. Even slight changes are showing notable differences. That's the big take away so far. It's a learning process.

I have seen quite a few people with road positions around .25-.3. Mine was .26 last time I tested, the .25 might have been due to some testing protocol error, but that same rider is .24 on his TT rig! It might be fairly good for dudes on the interwebs who tend to document their testing publicly. .3 was for a rider who clearly had a high/ugly position. Many of the low numbers were final- we adjusted the bike fit for power and efficiency. In most cases the seat height was slightly lower than predicted by just fitting and riding on a trainer, reach was a tad longer and bars almost always a bit higher. There is a ton of room for road bike improvements through fit, but that alone is going to result in MUCH higher reductions than this frame testing stuff.

From what I've seen, allowing more forward pelvic rotation usually aligns the spine and drops the shoulders and head typically. Optimizing spinal extension and pelvic rotation can dramatically reduce rider height and usually a better bar/hood position can further allow the rider to drop their head and bring their elbows in closer.

Considering you said you were dropped at Winters on the climb, I'd look internally for more motivation to train since you could hide in the pack with whatever aero and sprint/attack near the end, which is how almost every cat 3 race goes anyways.

THIS ...... body position .... is what I would like see you testing Ryan as it seams to have way more impact that any Aero frame or any other Aero parts will have.

[RyanH]

@KarlC, since I was hoping on getting rid of the Foil and Cervelo, my next rounds of tests will be focused on that.

These are the things I plan on testing:
175mm -> 165mm cranks (thoughts on adjusting position? Ideally I'm hoping I can absorb the extra 1cm reach and extra 1cm of drop).
110mm stem -> 125mm (in progress)
40cm 3T Ergonova bars -> 40cm Enve Aero Bars (hood position going from 38cm to 35.5cm)
Maybe SRAM Rival vs eTap?

Since KWalker mentioned it, fine tuning my road position has my curiosity piqued so I'd like to test that. I may do the camera method where you take a picture, cut out your image in photoshop then get the pixel count to use as a starting point then test.

A non-aero to aero bike is theoretically good for a 0.025 change in CdA (based on Tour's proposed 30w savings at 45kph). Curious how much position can make up of that. I'll post up a picture later of what my position was on the Cervelo, as well as my position with the longer stem.

[KWalker]

Dude, don't waste your time on cranks unless you have hip functionality issues OR you're really short. If you do adjust, have a good fitter do it for you. They're not going to make or break you. I went from 175 to 170 and there was 0 difference.

Get an adjustable retul fit stem. It's clearly not safe enough for riding long distances, but allows for very quick testing differences.

Narrower is not always better if your elbows flare too much.

eTap just because it's *f##k* sweet.

Pixel count works, but is only part of the picture. A big key is to test your helmet shape. I'm much more slippery with a bobtail/short tail helmet and even without much elbow bend for me lower is always better.

Saddle position enables all of this. I would much rather drop 2-5mm and alter saddle position to enable pelvic rotation than mess with cranks. Looking at your saddles they are very light but none of them are designed with biomechanics in mind. IMO this is where the Speci and Bontrager saddles tend to pwn all others. Switching from a Romin to a Power allowed me to drop my bars 1.5mm and move them out 1cm. Big difference.

The issue with this sort of testing is that road bike tests are not commonly documented online. This was something I sold as a service, but nowadays I don't have to and since it's a fairly boring subject have no interest in doing a big blog/write up about it. Sure most others are the same.

[Grill]

A really good road bike position is in the range of .260m^2. The best bike positions are <.180m^2 (I know of a few below .170m^2)

I am assuming these are all at 0º? If so, I'd love it if I could hit those numbers on my Time Trial rig let alone my road bike. I'm curious, though, as to the size of the individual that is .260 and more so of those that are sub .180.

Between 0 and 5 degrees (velodrome tested). I don't really see much higher than that unless it's a long race. The guy at .260 on a road bike is 85kg. Although I don't know their exact numbers, here are a couple that are easily below .180.





And here is me at 78kg who is not as aero as the two above, but not far off either (although not on the wheels show, fast ones were getting new tubs at the time).

[RyanH]

Here's a few quick snaps on the current setup. Doing a timer and jumping on the bike is a pain to get right.



Normal drop position:



Aggressive, chasing someone down position:



In the last position, I'm maxed out with respect to knees hitting the stomach/chest.

[cyclespeed]

@cyclespeed, when covering a fixed distance, aero differences are more pronounced the slower you go (time wise).

In example:
40K@200w
Speed @ CdA of 0.32: 34.072402
Time: 70.438 minutes
Speed @ CdA of 0.31: 34.412557
Time: 69.742 minutes
Time Difference: 0.696 minutes

40K@400w
Speed @ CdA of 0.32: 43.864276
Time: 54.714 minutes
Speed @ CdA of 0.31: 44.312922
Time: 54.16 minutes
Time Difference: 0.554 minutes

So, I think it's a generally incorrect statement to say that aero benefits kick in at X speed. If you're racing an Iron Man for the first time and expecting to average 15-16 mph on the cycling leg, a very aero setup is going to net you a lot more time saving (in absolute terms) than the top contenders. I'm too tired to calculate the percentage differences, which may be the inverse. But, moral of the story is that aero benefits everyone regardless of speed traveled.

OK, fair enough, i get the 'slower rider saves more time' thing, even though I feel it disguises things slightly, as, expressed as a percentage of time saved, the faster rider saves as much as if not more. (as a %).

I guess my mind is approaching this in reverse. How about you were to ride at a set high speed of 12m/s (43km/h) over a 2km (approx) lap. Your average power is say 250W. Then you swap for a fancy aero helmet and you notice that on the next run your power is now 235W.

Had you done this test at say 33km/h the power saving would be much smaller (about 6W), thereby less easy to detect.

I realize that it is easier to do a set distance than a set speed, and that this would be easier on a track, but it should be feasible to achieve reliably constant average speeds with practice. Runs would need to be over the same course to eliminate wind and gradient variables.

Of course, again, you have to keep your position constant, and keep wind out of it as much as possible.

Not saying this is a better method necessarily, just a different one.

[RyanH]

@cyclespeed, when I first set out to do this test, if you peruse back to the first page, my goal was to do this for an hour at exactly 240w. Why? Because I was hoping to be able to guage which was faster solely on distance covered in exactly 60 minutes. What I didn't take into account was the effect of air density (Rho). A 20*F difference in air temperature can mean a difference of a couple MPH (that's fuzzy guessing but it's not too far off) for the same power.

[Stalkan]

A really good road bike position is in the range of .260m^2. The best bike positions are <.180m^2 (I know of a few below .170m^2)

I am assuming these are all at 0º? If so, I'd love it if I could hit those numbers on my Time Trial rig let alone my road bike. I'm curious, though, as to the size of the individual that is .260 and more so of those that are sub .180.

Between 0 and 5 degrees (velodrome tested). I don't really see much higher than that unless it's a long race. The guy at .260 on a road bike is 85kg. Although I don't know their exact numbers, here are a couple that are easily below .180.





And here is me at 78kg who is not as aero as the two above, but not far off either (although not on the wheels show, fast ones were getting new tubs at the time).

We have a different definition of Road Bike. Yes a Time Trial bike goes on the road, but for me there is a difference between a "road" position and a Time Trial position. These positions are not something I thought we were discussing I simply posted my baseline as it was close to what some were claiming they could hit on a "road" bike. BTW, my current position is closer to the pointy end of what you are suggesting, but that is apples to oranges for this discussion.

Edit: I see you mentioned the .260 for the road bike and I buy that as possible, but I thought you were suggesting the .180 was on a road bike. Hence, my slight disbelief.

[KWalker]

Posting static pics in street clothing tells us nothing, but your lower back looks super rounded. Probably saddle too high and too far forward. Look really crunched up and your shoulders are high as a result. Think of the cat/camel yoga routine if you will.

Considering where you are at and your access to both Nor and So Cal, I would enlist the help of a great fitter. With the power numbers you've claimed at the weight you claim you're supposedly numbers wise stronger than a ton of cat 1s I know, but if Winters was trouble in the 3s I'd spend your $ and time on a better fit personally speaking. Looking at some power from guys I know and their report of the race, the pace was pretty mild AND if your aero was good catching on after Cantelow shouldn't have been tough. Not trying to be a dick, but this thread is a massive time suck and you haven't touched the most important aero variable- your position.

[RyanH]

KWalker, you may preface that you don't intend to come across that way, but it does. You're missing the point of what the intention of this thread was and how it evolved over time. Coming in and telling me that I'm doing it all wrong after the fact is dick. I've been open about the process and solicited feedback the entire way.

Regarding the race, I said before, we scooted around at 18mph and then attacked the climb. My power profile is crap since December because I've averaged 80 hour work weeks Dec through April. Sure, I've been riding a lot for the past few months but I haven't done any top end work. I also haven't raced since March. Winter's was a spur of the moment, "hey I'm in Napa for the weekend why don't I do a race to see where my fitness is." I got my answer, my endurance is good but my sub 10 minute power is terrible and I'm having trouble recovering from anaerobic efforts. I probably would have stayed with the group had I sat in the entire time but I went with an attack. I didn't feel like this was really necessary to bore everyone with since it's irrelevant to this thread but you keep bringing it up as if my position on the bike was the reason I got dropped...