AeroPod as CDA measurement

[super slim]

Has Larry or anyone purchased a Velocomp Aeropod ($500) and used it with a direct measurement power meter and a new Garmin (520,820,1030 edge) GPS to give ACTUAL real time CDA readouts on the Garmin?

https://powermetercity.com/product/aeropod-power-meter/

It would have saved hours on his secret test track, testing all the wheels, handlebars, etc, AND given CDA at different wind approach angles as he rode around the track!

 

[RojoRacing]

I'm waiting for version 2 after they work out most of the glitches, make the unforeseen improvements and such.

 

[ed72]

What RoJo said.

Where I think it would be very useful in determining the best position WRT hands, arms, head, neck, etc. This is very time consuming at least for me. Comparing wheels or helmets is quick and easy using the Chung method at least under steady-state conditions. For instance, it would not help quantify the effect in very turbulent conditions such as the buffeting and bluff body effect of a tailbox in traffic or gusty crosswinds.

I can see a day where Bestbike splits, XERT, and an Aeropod type device would allow a completely optimized TT or Tri leg.

 

[cranky cyclist]

I wonder how well this would work on a cruzbike as there would be a lot of turbulence generated by pedaling. Wouldn't this distort the power numbers?

 

[super slim]

I wonder how well this would work on a cruzbike as there would be a lot of turbulence generated by pedaling. Wouldn't this distort the power numbers?

I think it would have to mounted below and in front of the bottom bracket to get clean air!

 

[ed72]

I looked at these devices a year ago and just did another look. It is still too soon for me.

A similar mounting challenge exists to TT bikes. Chung on a Stick just needs a longer stick to get the device far enough out on the BB although the sensors could be integrated into the BB (or headtube on an upright) assuming averaging and post collection filtering would be "reasonable" CdA figures but color me a huge skeptic and not an early adopter. I want proof beforehand. The Chung VE Field testing method is very sensitive and not that hard to do albeit time consuming. It is much more sensitive than coast down testing. For instance, I would repeatedly hit the same top speed (resolution is +/- 0.2 mph) on a coast down but I could measure a consistently difference of around 5-7 watts at 25 mph (0.006 m2 approx) on a calm day. On a windy day? Forget it. Real time aerodynamic data has been easily collected in a velodrome for many years and is probably a better value proposition than visiting a wind tunnel depending upon one's location. (if you live near A2, obviously that would be cheaper). One advantage of velodrome testing? Wheels are moving, pedaling, and rider movement (steering changes drag considerably in certain conditions) are more realistic than in a tunnel.

I suspect many riders will chase their tails when the first get one of these devices simply because day to day differences in temperature, humidity, barometric pressure, wind, road surface quality, and other factors have a significant effect on the estimation of CdA and I doubt these effects can be normalized from day to day until an internal calibration can be implemented. Sure, it would be easy to show the difference between upright on the top vs. down in the drops. DCrainmaker demo'd that.....it goes from 0.460 to below .300. Who wouldn't already know that? But what if a rider is a TT or Tri specialist with CdA already at 0.215 seeking 0.210 or 0.205? A much higher level of accuracy and precision needed. I already know my wool randonneuring jersey is lousy in the wind and swapping it for a tight aero jersey drops it by 0.03 and going to a skinsuit drops it almost by 0.040. It is easily measured using the Chung method. If an aeropod type device could not quickly and reliably detect such a difference, I'd say it was worthless because such reductions in CdA on a bent give huge performance improvements (2-3 kmh).

 

[ed72]

RChung's comments give pause, too.

My reference to tailchasing has to do with introducing systemic error from day to day.

It is interesting that Notio Konect (Aeropod competitor) introduced the first 500 units but only to users trained at shows or 1/2 day seminars.

In my case, the cost isn't just the meter. I'd need a more recent Garmin unit, mine is an older 800 and doesn't have the IQ connect capability. But, it would be worth it. I probably spent 50-100 hours to knock my cda down and still searching for another 0.010. eTap is probably a better use of $1000 bucks. Eliminating the shitfer cables would cut half that. Dropping 30 pounds of fat is the other half. LOL

https://forum.slowtwitch.com/forum/...d)_experiences_with_Notio_Konnect_P6676239-2/

 

[ed72]

So, it is a slow morning babysitting my mother-in-law.

Aeropod apparently is holding Crr constant in the initial version.

FWIW....I have measuredd Crr down as low as 0.0042 ish (Supersonics on good paved roads) to as high as 0.008 with 0.005 being typical on normal decent country roads around here using 25 mm Conti GP4ksii and latex tubes. What does this mean? If I assume a Crr of 0.008 on a recent set of VE data, I get a CdA of 0.140 ish whereas if I assume a Crr of 0.004, I get a CdA of 0.180 ish. This means to me that the initial version of Aeropod can only be used to test on a controlled venue. On the same road surface. Road surfaces can vary a lot and holding the Crr constant is a huge limitation, in my opinion.

7) For our "release 1.0" we are going to hold Crr constant. We are fully aware that this is a limiting assumption, but it is a start. Once we have things settled down we will focus on relaxing this assumption.

https://forum.slowtwitch.com/forum/...bike_measurement_device_kickstarter_P6612344/

 

[super slim]

The draw of this device is to test the effect of different riding positions or clothing, pannier bag positions, OR different bikes, on the same road weather conditions, that give CHANGES in CdA results, INSTANTLY, so assumed rolling resistance does not matter!

 

[ed72]

The draw of this device is to test the effect of different riding positions or clothing, pannier bag positions, OR different bikes, on the same road weather conditions, that give CHANGES in CdA results, INSTANTLY, so assumed rolling resistance does not matter!

None of the reports suggest the technology is currently sensitive enough to measure changes in position like arm or hand position nor have any of the manufacturers released study reports.

You don't really need to use capitals.

I get the potential advantages. It just isn't there yet. That is the reason for my having made the following comment.

This means to me that the initial version of Aeropod can only be used to test on a controlled venue.

I can't see V1 being helpful in real world conditions other than for riders who have are unaware of gross aerodynamic effects, my comment was primarily due to large variations in road surface quality (where I live) aside from other considerations such as the highly turbulent airflows on real roads (not easy to measure real time) although it should be easy to do in a Chung loop or halfpipe on a not too windy day. The one Mfg's reports of 0.000 accuracy and precision is laughable to anyone who has done aerodynamic testing in the field or knows anything at all about anything. Another reports 0.001. Sure. Santa is coming too. Anybody have a power meter even that accurate? They don't exist. If you don't believe me, read what Chung wrote on some of the links I posted.

 

[ed72]

The UK Time Trialers are a bit more balanced and far more experienced than ST. Lots of good scientists and top TT ers there.....for another perspective.

MFgs should produce scientific validation showing repeatability and reproducibility of their instruments but they don't. Why?

http://www.timetriallingforum.co.uk...ocomp-launch-dynamic-cda-power-device/&page=3

 

[super slim]

When Jason gets his Aeropod Ver 2, we should see data, and his opinion or the device to measure changes in CdA!
If you want absolute accuracy, then hire a wind Tunnel at $1,000/hr

 

[ed72]

When Jason gets his Aeropod Ver 2, we should see data, and his opinion or the device to measure changes in CdA!
If you want absolute accuracy, then hire a wind Tunnel at $1,000/hr

Good Lord.

Why do I waste my time.

Is Jason a degreed professional engineer with 40 years of experience on this sort of thing?

If you took the time to read the opinion on some highly experienced coaches, scientists, and TT experts on the forums that I linked, you'd see that this device is currently a novelty for the uninformed. In the hands of an experienced person, it could have some limited value but not to the extent dreamed about. In time, it will get there. But not yet. If someone wants to drop $500, go for it. Unless you control carefully, you won't be able to tell if helmet A is better than helmet B although gross errors in positioning "should" be detectable. 0.000? 0.001? Right.

Aeropod not only ignores Crr, it doesn't measure YAW.

Wind tunnel time is not $1000 per hour, besides better results can be had for free, Google Chung Field testing. I lowered my CdA from 0.200 ish to 0.150 is using it.

What is frankly very laughable is seeing the typical bent rider with $3000 worth of wheels riding with a flappy jersey that an hour using the Chung method would point to real improvements.

 

[RojoRacing]

Good Lord.

Why do I waste my time.

Is Jason a degreed professional engineer with 40 years of experience on this sort of thing?

Well now that you mention it I do have a degr........................ oh never mind it was a degree in sarcasm, sorry false alarm.

 

[jond]

Ye old slim be an engineer.

 

[jond]

So, it is a slow morning babysitting my mother-in-law.

Aeropod apparently is holding Crr constant in the initial version.

FWIW....I have measuredd Crr down as low as 0.0042 ish (Supersonics on good paved roads) to as high as 0.008 with 0.005 being typical on normal decent country roads around here using 25 mm Conti GP4ksii and latex tubes. What does this mean? If I assume a Crr of 0.008 on a recent set of VE data, I get a CdA of 0.140 ish whereas if I assume a Crr of 0.004, I get a CdA of 0.180 ish. This means to me that the initial version of Aeropod can only be used to test on a controlled venue. On the same road surface. Road surfaces can vary a lot and holding the Crr constant is a huge limitation, in my opinion.



https://forum.slowtwitch.com/forum/...bike_measurement_device_kickstarter_P6612344/

I was going to ask for photos of skin suit tight jersey and merino top...........lol. 30 pounds is not a lot.

 

[super slim]

I lowered my CdA from 0.200 ish to 0.150 is using it.

What height are you, and what wheels are you using, as Maria who is 5'2"??, only got down to 0.158 with two Zipp Full disk in the A2 Wind tunnel?

Any photos of you from the front and side?

https://cruzbike.com/blog/2017/02/0...d-tunnel/?mc_cid=2778c78d3f&mc_eid=d90a76f6f3

It cost a min. of $1,100 for two hours, not one as I thought!
View attachment 7451

Larry, who is 5'5"???, has spent a LOT of time trying LOTS of different handlebars, wheels, helmets, enclosed area behind the seat, drink bottle locations, 140 mm cranks, etc, and using his suicide bars only achieved 0.21 Cda in the wind tunnel.
Looking at photos of him racing with other Cruzbikers, he has the smallest cross sectional area by a large margin!

View attachment 7450

 

[Bill K]

Well, my inner-data-geek convinced me to get one of these.
I rode with it yesterday to do a calibration ride followed by a simple capability test.
Unfortunately I got no data from it. My power meter decided to act up the entire ride with constant dropouts (probably low battery).

What should have happened:
Pair the AeroPod to a DFMP power meter (Power2Max on my V20) and a wheel speed sensor, and pair it to the Garmin to display data.
Do an out and back calibration ride.
My V20 has a dynohub with a well known power curve. Lights on draws 5 watts and lights off draws less than 1/2 watt.
Do a number of laps (at least 3-minutes each) with lights either on or off to test cda.
Ride home, load the data into Isaac (the data analyzer software for the AeroPod and other Velocomp products) and view the cda data for each lap.
If it clearly detects lights-on laps from lights-off laps then this should be a very useful tool.
Unfortunately, no data this time.

It mounts nicely underneath the bottom bracket if you buy the additional "PowerPod TT" mount.


Stay tuned... as soon as it stops raining and the streets dry out I'll take it out for another try (with fresh batteries this time).

 

[DavidCH]

I lowered my CdA from 0.200 ish to 0.150 is using it.

What height are you, and what wheels are you using, as Maria who is 5'2"??, only got down to 0.158 with two Zipp Full disk in the A2 Wind tunnel?

Any photos of you from the front and side?

https://cruzbike.com/blog/2017/02/0...d-tunnel/?mc_cid=2778c78d3f&mc_eid=d90a76f6f3

It cost a min. of $1,100 for two hours, not one as I thought!
View attachment 7451

Larry, who is 5'5"???, has spent a LOT of time trying LOTS of different handlebars, wheels, helmets, enclosed area behind the seat, drink bottle locations, 140 mm cranks, etc, and using his suicide bars only achieved 0.21 Cda in the wind tunnel.
Looking at photos of him racing with other Cruzbikers, he has the smallest cross sectional area by a large margin!

View attachment 7450

That's why he is so darn fast. It helps having one of those cruzbike carbon bottle race case at the back too.

 

[ed72]

I lowered my CdA from 0.200 ish to 0.150 is using it.

What height are you, and what wheels are you using, as Maria who is 5'2"??, only got down to 0.158 with two Zipp Full disk in the A2 Wind tunnel?

View attachment 7450

It seems to me that their wind tunnel experiments were more focused on the tailbox and water bottle arrangement, which I found interesting because it stacks up with my experience. Namely, a tailbox and/or bottles are not beneficial in higher yaw wind.

Of interest is the seemingly inexplicable approximately 25 watt increase from 0 degrees to 7.5 degree yaw with the dual disc setup and only a couple watts increase with the Boyd 60 front and disc rear. This makes no sense even discounting the too wide of a tire on the Zipp front disc, which could possibly lead to separation and higher drag at a lower yaw but those two results there are highly suspect. The 7.5 yaw conditions with two disc should require lower wattage, not 25 additional watts. We know very little of Larry's setup during this test but he has provided plenty of real data proving a much, much lower CdA than 0.210. Was he on the Frankenbike? Skinsuit? Shaved? Compression socks/legs? Hairy skin is very slow. Skin is slow. Compression socks and/or arm sleeves help quite a lot. Etc. Top upright TT racers have lower CdA than 0.210.

My rear wheel is either a covered HED Belgium plus or Zipp 404, both laced to a powertap that check out to factory specs on calibration although one is like 1% high and the other 2% low but within specification. The Zipp is faster. Tire width doesn't matter much back there but I run a Vittoria TLR Speed 23mm or Conti TT 25mm and we know which is faster. The front is either a Flo60 carbon with 23mm Conti Supersonic or a M5 Two Spoke with Conti GP5000 23mm. In low yaw, the 2 spoke is marginally faster but significantly faster in certain wind conditions. Skinsuit is either Assos Cronosuit or a faster one from England (name escapes me). Socks from Nopinz. Giro Vanguish helmet. I'm 6'3''. I'm on an M5. Power meters are +/-2%, Crr varies a lot by temperature, atmospherics matter.....which is why I am a bit uncertain of my CdA but my 220 pound carcass usually needs 255-260 watts for 29++mph average over 10 miles on a flat river road. It takes me 115-130 watts to go 21-22 mph on that same road back and forth many times, with Crr measured 0.0045. Pretty wide range. Lots of little things add up like cabling, hand position, arm angles, chin angles, position of cycle computer, etc. It is like when someone asked Ben Hogan for secrets, he said it is all in the dirt. Experimentation is needed on a rider by rider basis and the Aeropod could really speed that up, but color me skeptical.

I hope this helps or at least addresses your question.