Aeropod high accuracy test for 40k TT real world validation peer check

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gte534j
Posts: 11
Joined: Tue Dec 11, 2018 3:29 pm

Aeropod high accuracy test for 40k TT real world validation peer check

Post by gte534j »

Hi,
I am hoping I could have some peer review/check on my TT data from this morning 40k TT. Here is the details of the ride:
Bike: 21 lbs with water bottle at volume of fluid at start of ride.
2014 Trek Speed Concept Di2 11 speed
Quarq DFour power meter model PM-DZ-A1 Dura Ace Chain rings55/42T 11/25T rear. Power meter has been checked against a 20kg kettle bell weight and also zero offset before ride. It has the latest firmware 10. Dura ace chain ultrasonically cleaned and soaked in ceramic speed UFO drip wax prior day.
Garmin speed sensor on front wheel- verified that it picked up speed by spinning front wheel while stationary and garmin showing speed
Wheels: Dash disc rear Reynolds Aero90 front wheel with Vittoria Graphene 2.0 25c tubeless rear, front latex inner tube. Tire pressure rear 85psi, front 80 psi. Set rolling resistance as premium tires on asphalt blend.
Aeropod latest firmware (9.001 Manufactuer #8 Model 2054) purchased 12/2018 mounted on TT bar
Garmin Edge 1030 Plus latest firmware (6.4) with Aeropod App installed (you can see Cda, wind, slope and time advantage data on garmin connect link below)
Me:
155 lbs 6’0”
Champion systems carbon aero TT skin suit rear zipper
Aero gloves/shoe covers
Rudy Aerowing helmet w/ Oakley sunglasses
Photos:
https://drive.google.com/drive/folders/ ... sp=sharing
Atmospheric conditions at local airport (~6 miles away) (ride started around 9am)
9am-79F, RH 36%, Pressure -0.03” wind 5mph

I have attached my garmin file and also the Aeropod file in the post and also its in the google drive.
I setup the configuration in Profile 4 with highest accuracy. I did a out and back ride and the calibration ride prior to the TT went really well.

For the TT ride i stayed in aero position for just about the entire ride except for the U turn at about 18 min and 32 min. I think i got out of aero 2 other times as I was getting unforfortable. I did "sprint" the last 200m or so standing up.

From ISAAC it looks like my average CdA is 0.264 with the lowest around 0.233 and the highest around 0.287.
My garmin ride data is here:
https://connect.garmin.com/modern/activity/9216223333

Does this CdA seem reasonable and correct?
I am looking at improving my aero position and I *believe* that my CdA is not very good compared to others when I have done races and seen other people have faster times with less Watts/kg than me, which implies that their Watts/CdA was better.
Attachments
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Velocomp_07_16_2022_0852_2_Miles-40kTTcalibration.ibr
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Velocomp_07_16_2022_0858_28_Miles40kTT.ibr
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Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Aeropod high accuracy test for 40k TT real world validation peer check

Post by Velocomp »

Your ride file tells the story:

1) You were in profile 4

2) Your DFPM watts were very consistent throughout the ride
Screen Shot 2022-07-17 at 4.42.47 PM.png
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3) Your AeroPod watts were fine at the beginning, until km 18, where your cadence briefly dropped to zero. After that your watts were way low. Why? Because your AP was bumped; notice that the slope goes negative, even though you were climbing a hill!
Screen Shot 2022-07-17 at 4.52.03 PM.png
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4) The only valid data you have is from km 4 to km 18. In this section your CdA was .242
Screen Shot 2022-07-17 at 4.55.02 PM.png
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5) Your calibration CdA of 0.144 is really low.

6) When you're doing a time trial or training ride, it's better to use profile 3, where this kind of problem will self-correct.

I am concerned your AP is not securely fastened to the mount. Make sure it can't rotate on the mount and then you should get better results.
John Hamann
gte534j
Posts: 11
Joined: Tue Dec 11, 2018 3:29 pm

Re: Aeropod high accuracy test for 40k TT real world validation peer check

Post by gte534j »

Thanks so much for the analysis.
There was a really rough train track at 18km in- so i briefly stopped pedaling so i could make it over it (back and forth twice). That probably messed w/ the aeropod and screwed up the rest of the data. That makes sense now to me and I was wondering why the CdA data was flat after that.

I dont know why my calibration test CdA was so low. I did the test the same way I did the rest of the ride. Do you think the aeropod position had issues during the calibration?

I have attached two photos of how i attach my aeropod to the bike. Is there a better way to attach it to my Speed concept?

Thanks so much for the help- i really appreciate it.
Attachments
aeropod-mount.jpg
aeropod-mount.jpg (104.92 KiB) Viewed 3855 times
aeropod-mount2.jpg
aeropod-mount2.jpg (128.61 KiB) Viewed 3855 times
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Aeropod high accuracy test for 40k TT real world validation peer check

Post by Velocomp »

The problem is your mount. There is no way Zip ties are going to keep your mount stiffly attached to the handlebars.

This is also the cause of your low test CdA.

Please contact technicalsupport@velocomp.com with your photos. Tom will give you a much better mounting option.
John Hamann
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