Second person helps get the skinsuit over the shoulders. I have to put both arms on at the same time, hike the sleeves up really high (so there's enough fabric to get over my shoulders) and then readjust everything afterwards. :) I believe it was "Carl Spacker" who said that nothing motivates a diet like putting on a skinsuit...

Bummer, I was hoping you'd say, "well, there's a couple big, handy pockets in the back of the Desoto"... crazy the difference!

Looks like you've got a good season ahead of you!

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

Geez, you really need a better handlebar setup. Something that allows you to angle the extensions.

Did you ever test the stacked hands versus high extensions positions?

Hey
If you want, you can send me your data, I have a code that corrects for change in temperature (if the powertap or your computer measures this), among other things.

And I dont know why theres not much actually done in skinsuits commercially but the gains can be huge! I dont know your skinsuit but maybe youre lucky. And congrats on your overal air resistance, I wish mine would be that low...

Hi, I'm keen on giving this a try. I live in a some what busy area, so I could use some tips for course selection. I have access at certain times to an empty parking lot, though there is a flag nearby and evidently it's typically pretty windy there. I can also go a little further to a parking garage, which one would also expect to be empty. It's not totally enclosed, but it has half height walls so the wind could be less there. I could probably put up cones to block it off without anyone complaining. Any other tips? Do you suppose a power tap and a joule 2.0 is sufficient for the data collection?

Thanks!

Alright, let's get this going.

If there is a prevailing wind direction, I would align an out-and back course about 400-600m in total distance (out and back) with the wind. Then make sure you have a good handle on the air density at the time you test.

Once you have the data, we can have a look at it, ok? Have you read the protocols in the previous thread posts? Have you looked at jbanks' website?

If so, then you're ready to go.

G'luck!

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AndyF
bike geek

I have been working a bit with the Aerolab function in Golden Cheetah, but I am finding it really hard to get good repeatable "loop" data. I do, however, have a really nice hill outside my front door. So I did some runs up a 600 m stretch with 20 m of elevation gain.

What I had hoped to do was to use the "Crr and CdA on constrained elevation gain" method give in on slide 43 of 112 in the R. Chung presentation/aero bible presentation. I coded everything in R and I think my data and estimated elevations are pretty good, but I notice that my graph doesn't look like the one in the presentation. The big difference is that I calculate a zero-intercept, but the graphs on slide 43 are not constrained. Can you enlighten me?

Thanks

P.S. I can send R code and data files. I also implemented some optimization routines the find "best fitting" Crr and CdA values and I have fund that "best" is a relative term.

Ah. The actual runs start at km=0 and elevation=0. I just snipped off the first 1.75 km and the first 100m of elevation gain for that slide.

I'd be interested in seeing your R code. I've tried some black box optimization but I still find that I learn more from looking at the VE profiles as diagnostics.

Ah, that would explain the different intercepts.

I will document the code a bit and send you a PM for an email address. I also GPSed the end points of the ride. Assuming the GPS data are accurate (I don't know much about GPS accuracy, but I just updated my iPhone GPS location until it stopped changing elevation values) my estimated elevation profiles are with about .5%.

Thanks. I think my email address might be on the front page of that document. GPS altitude can be a little coarse for this kind of thing -- but you should try it to be sure. For that slide the hill happened to have topographic surveyor's benchmarks right near the start and end so I was pretty sure what the elevation change was.

So I'm trying to get familiar with the Aerolab tool, and I'm in need of some help from the collective wisdom, as the GC help pages are a bit thin to say the least.

I did some baseline data gathering, varying the speed (pushing harder) for the middle lap of 3 laps to have data to tease out Crr from CdA. But when I'm looking at the data in Aerolab, the Crr and Cd control sliders seem to affect the VE curve in exactly the same way and my middle lap has a larger elevation change no matter what pair I choose. Am I not setting up the tool correctly, or did I do something wrong in the data collection that could be causing this?

From memory, if you want to address both Crr and CdA then you need to add elevation to the equation.

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Ironman Certified Coach

Currently accepting limited number of new athletes

Anyone in Orange County, CA doing VE testing? This is the land of coastal wind, stoplights, and road medians... Any tips on a good testing site are welcome. Thanks!

i'm curious to know. if .005 = 5 watts @ 30mph, what is .005 at 25mph or 28mph? is there a chart? and how does that equate to time saved (or added) per kilometer or mile?

i've been playing with this at various industrial parks on the weekend, there seems to be good data collecting but still questioning my settings and analysis for accurate #'s.

It's a rule of thumb, but it's a pretty good one, so it's pretty close at 25, 28, or 30 mph. If you really need to know the exact number you'll have to calculate.

for me.................4.3/6.0/7.4w at 25/28/30mph for .005CdA +/-

I’m in the midst of trying to hone in on using Aerolab properly. I’ve read the string a few times and studied the PDF doc as well that explains Chung’s Aero testing and VE. I’ll try to keep it short; here’s what I’ve done:
· Testing TT position, standard hold on extensions to find a baseline cda#
· Terrain – outdoor industrial park that has no stop signs and limited to no traffic on weekends
· Winds very light but increase throughout the day
· Used some apps to retrieve data on humidity, temp, Rho, Air density, etc
· Rode 3 loops on a .9mile loop (egg shaped) and started lap 1 at 250W, lap 2 at 270 and lap 3 at 290, essentially 1 shift harder per lap….i wasn’t shooting for specific power targets but they came out close to this
· Garmin 500 capturing data at 1sec intervals and speed sensor is connected and Quarq PM is calibrated prior to each run

Once completed, I uploaded file into GC and looked at the Aerolab. I slide the number bars to reflect the CRR, Mass & Rho…I left CRR at 5, because that seems right and I figured if I compare with the same wheels on the same day with the same tire pressure then that shouldn’t affect the faster v slower…maybe not the most accurate cda # but on a comparison, I’ll find the fastest position…fill me in if this is incorrect.

Now to my real question – when sliding the cda bar, am I supposed to use the constant altitude box checked or unchecked or does it matter?

Also, the 2 charts below show the difference with the box checked and unchecked. I like the straight bar to connect the start and finish points clearer but is this correct? OR is the difference of .0007 so minor that I’m splitting hairs? (i can't seem to upload my images)

Lastly, as a confirmation, am I doing conducting the field testing correctly?

https://drive.google.com/...1ETHc&authuser=0


https://drive.google.com/open?id=0Bybxljl8xw55VVBuVGg1bVNfdXM&authuser=0


Thank you.

There's poor fit between the VE and the altimeter. Something's off.

Thanks RChung - any suggestions? i'm not sure what's off?

How did you get the data off the Garmin 500 and into GC? Did you download it directly?

i took the Garmin fit file and uploaded to TrainingPeaks and and did an elevation correction. From there I sent to WKO+ and GC.

Is the .fit file still on the Garmin? Drag it to GC directly, without going through TP or correcting elevation. I'm not saying that's the problem, I'm trying to eliminate possibilities.

i've already deleted the .fit file. I'll re-run my testing soon and try dropping the .fit file directly to GC w/o doing anything in TP. Is my field testing protocol correct?
thank you very much.

Yes, looks reasonable.

Do you still have any rides whatsoever on your Garmin? Drag any .fit file into GC and look at it with Aerolab. For this, you're not trying to guess your CdA, you're just trying to see whether you can get the data into GC without any intervening step that may have altered the data.

[Edited to add:] What I'm seeing from your screenshot is that your outdoor industrial park has a series of relatively steep ups-and-downs. Your altimeter trace suggests that you climb ~20m in the first 400m, that there are sudden and sharp changes in elevation, and that there is a steep descent (around 15m in 100m) back to the start of the loop. I'm wondering if this could be an artifact of the "elevation correction" algorithm in TP. The VE profile, on the other hand, seems to show a much flatter industrial park loop. Perhaps you can say which of these two seems to more accurately describe the industrial park even though you no longer have the .fit file.

Good catch, I definitely did not climb that much. This loop does have a false flat but nothing close to a climb. I do have an old file (same loop, more laps) i pulled from the 500 and directly put into GC, it looks better...but i'd love to hear what your expert eye sees. The 2 shots below are the same loop just with "constant alt" checked and unchecked. So, if i was using this file, would i match up the VE with the V and level the start/finish points of the VE to give me the cda#? does the .2453 look correct?


https://drive.google.com/open?id=0Bybxljl8xw55cllHWnB0YVFuUkU&authuser=0
https://drive.google.com/open?id=0Bybxljl8xw55QzREbkxyMDlkQW8&authuser=0


I really appreciate the feedback.