Real World Aero Testing via Chung Method - Data Thread

[cyclespeed]

I thought it was interesting to see Fabio Aru doing the Megeve TT (fast) on a Tarmac......

[wingguy]

Yes, but how negligible is negligible when it comes down to 2.5cm in a 70kph sprint? How many watts of frame drag does it take to change that outcome?

But even then you don't even consider the stiffness of the frames, the cda of the wheels, the grip and rr of the tires, the clothes, the shoes, the bars, the helmets, the total energy lost. You just attribute those 2,5cm to the cda of the S5. How do you know? In theory you may be right but in practice it does not work like that, especially in a sprint where the frame moves in multiple directions.

Uh, yeah, I did consider all of that actually. In fact, I did and you didn't. You said that nothing mattered except body position.

Look, if you can't be bothered responding to what I've actually written then I can't be bothered talking to you either.

[RyanH]

Alright guys, there's plenty of other threads we can debate this stuff. As kgt said a few pages back, let's keep this thread clean for testing.

Also, I want to add that if anyone else would like to contribute to this thread following similar methodology, I think we would all welcome it. Just bear in mind that we're sampling relative CdA's so be prepared to test multiple variations of equipment multiple times.

Sent from my SM-G930V using Tapatalk

[deek]

I'd just like to say thanks for doing this, Ryan. It's all really interesting. I need to get off of my lazy butt and do something similar.

[AJS914]

I applaud your efforts!

After all the testing so far do you have any comparative conclusions or are you back to square one with using a wheel sensor over gps to measure distance?

I'm looking for the management summary.

[RyanH]

GSC10 Run 3: Cervelo R5ca* on 404s with 23mm Veloflex Criteriums
Recording Device: SRM PC8
Speed Sensor: GSC-10
Tire Pressure: 90F/100R
Beginning Temp: 74*F
Ending Temp: 75*F
Wind: 1-3 mph N
Avg HR: 147 bpm (day after rest day)
Avg Speed: 21.8 mph
Avg Power: 238 watts
Distance Covered: 15.658
Duration: 43:04
Estimated CdA: 0.3365
Wind Adjusted CdA: 0.3365
Quality Rating (out of 3): 2 (average)

Ride Data (Strava)
Google Sheets Aero Data

Notes: Rapha 2015 Pro Team Jersey (aero).

Test Setup:


Chung Method Aero Analysis


Atmospherics (beginning of session)


Comments:
There was occasional wind coming from the North, so a headwind on the climbing leg. It was on and off. Had it been a constant 5kph, that would warrant a 4% adjustment. This run was about 1.8% slower than the previous run but any adjustment would be a guess so I'll leave it as is.

* This session's power data came from an SRM vs the other bikes are using the same Quarq.

[RyanH]

I applaud your efforts!

After all the testing so far do you have any comparative conclusions or are you back to square one with using a wheel sensor over gps to measure distance?

I'm looking for the management summary.

Thanks! I'm pretty sure it's back to square one. The CdA's have been much more consistent with the wheel sensor (granted, only 3 samples).

I have a separate concern when I go back to testing the Foil (or Fuji for that matter). I was getting a lot of power spikes with the Quarq. I never had that problem with my previous Quarq and a Garmin, so I'm not sure if it's the PC8/Quarq combo or the Quarq needs to go in for service. Maybe it's because I'm using the accelerometer instead of the magnet?

Oh, and don't hold your breath for an executive summary any time soon. To keep things statistically significant, I think I'll need at least 10 runs of each combo assuming the standard deviation is low. If it's like before, then that number will grow significantly. I'll do a few more runs on the Cervelo then do 5 on the Foil to get us a preliminary idea. I'm now wishing I had picked up a Cervelo S5 instead as it would have given me the flexibility to test narrow bars, various stem lengths and angles as well as not eat a large sum of money if I decide to sell it.

[Calnago]

I once tried to go a real life rolling resistance test between 23mm and 25mm tires. The management summary I came up with was it didn't really matter. But it's not fair to use the same pressure for each tire like I think some tests have done. I used what I believed to be the optimal pressure for each tire and my weight. Everything else was the same. I only did it because I wasn't buying the fatter tires are faster spiel. I couldn't prove one way or the other. I still don't think fatter tires are faster, but they are better for my size re handling and comfort so that's why I'm using primarily 25's versus 23's now. Anything more than 25mm does start to feel somewhat mushy on the road IMO. Kind of a sidetrack from Ryan's detailed testing but real world nonetheless.

[RyanH]

GSC10 Run 4: Cervelo R5ca* on 404s with 23mm Veloflex Criteriums (Will update tonight
Recording Device: SRM PC8
Speed Sensor: GSC-10
Tire Pressure: 90F/100R
Beginning Temp: 76*F
Ending Temp: 78*F
Wind: 0 mph (there might have been a few 1mph "gusts" but nearly every lap the flag was 0 value)
Avg HR: 155 bpm (day after rest day, plus being hotter and fighting a cold)
Avg Speed: 22.3 mph
Avg Power: 238 watts
Distance Covered: 15.656
Duration: 42:04
Estimated CdA: 0.3198
Wind Adjusted CdA: 0.3198
Quality Rating (out of 3): 3 (above average)

Ride Data (Strava)
Google Sheets Aero Data

Notes: Rapha 2016 Pro Team Jersey (aero). Pretty much zero wind the entire run.

Test Setup:


Chung Method Aero Analysis


Atmospherics (beginning of session)


Comments:
Today was a zero wind day. Quality of the run was very good other than suffering.

* This session's power data came from an SRM vs the other bikes are using the same Quarq.

[RyanH]

GSC10 Run 5: Scott 2016 Foil on 404s with 23mm Veloflex Criteriums
Recording Device: SRM PC8
Speed Sensor: GSC-10
Tire Pressure: 90F/100R
Beginning Temp: 71*F
Ending Temp: 73*F
Wind: 0 mph SE (just a few occasional brief gusts of up to 3mph)
Avg HR: 156 bpm (day after 4 days off of being sick)
Avg Speed: 22.0 mph
Avg Power: 241 watts
Distance Covered: 15.663
Duration: 42:42
Estimated CdA: 0.3326
Wind Adjusted CdA: 0.3326
Quality Rating (out of 3): 3 (average)

Ride Data (Strava)
Google Sheets Aero Data

Notes: Rapha 2015 Pro Team Jersey.

Test Setup:


Chung Method Aero Analysis


Atmospherics (beginning of session)


Comments:
Almost no wind, so a very clean run.

For those who were curious about the physiological effects of riding 5-6 days of Z3 for an hour plus group rides and pretty much doubling your weekly mileage, you can wonder no more: it compromises your immune system. I was hoping it'd manifest in the form of fatigue but by the time it did, I was pretty much already sick. So, sorry for the lack of updates, but that's why.

[RyanH]

Regarding fit differences between these two bikes, here's the pertinent measurements:

Scott Foil:
Saddle Tip to Front of Hoods: 71cm
Drop (measured from saddle nose to ground less shifters to ground): 7cm
Bar Width: 40cm

Cervelo:
Saddle Tip to Front of Hoods: 68cm
Drop (measured from saddle nose to ground less shifters to ground): 8cm
Bar Width: 40cm

The Cervelo I feel much more natural on and I find myself naturally in a nice elbow bent position. On the Foil, the 3cm extra reach feels fine for the most part, but I do feel upright, much more than I do on the Fuji even though they're the same drop. I also don't feel as relaxed which might mean that my natural position on the Foil is increasing my frontal area. This is also the first time I've ridden in 4 days, so maybe I'll feel more relaxed tomorrow and have a better aero position.

On a side note, I'm surprised the reach to the levers is so much longer. The bars must have more reach because the frame is only supposed to have 1.5cm more reach than the Cervelo, so I ordered a 1cm shorter bar to compensate but even doing so, it's still 3cm longer...

[RyanH]

GSC10 Run 6: Scott 2016 Foil on 404s with 23mm Veloflex Criteriums
Recording Device: SRM PC8
Speed Sensor: GSC-10
Tire Pressure: 90F/100R
Beginning Temp: 70*F
Ending Temp: 71*F
Wind: 0 mph SE (pretty much zero wind)
Avg HR: 153 bpm (still recovering from being a sickling)
Avg Speed: 22.2 mph
Avg Power: 240 watts
Distance Covered: 12.538 (I woke up late and only had time for 4 laps before Montrose)
Duration: 33:53
Estimated CdA: 0.3262
Wind Adjusted CdA: 0.3262
Quality Rating (out of 3): 3 (above average)

Ride Data (Strava)
Google Sheets Aero Data

Notes: Rapha 2015 Pro Team Aero Jersey.

Test Setup:


Chung Method Aero Analysis


Atmospherics (beginning of session)


Comments:
Almost no wind, so a very clean run.

Today's run was faster *BUT* I was also wearing a tighter fitting previous gen Rapha Aero Jersey. I'll do a run tomorrow with the normal Pro Team Jersey. I'm not enjoying this bike though so it'll be broken down at the end of the week. I may be interested in testing the new version (2015) Cervelo S5 if someone can track down one for a good price.

[kgt]

Just be careful not to turn the test into a Cervelo R5 vs S5 comparison. Don't waste your effort and time for that, the outcome is more or less known I guess. It's much more interesting IMHO to have three frames (non aero - semi aero - aero) from three different manufacturers as you did from the start.

[RyanH]

True except we have to keep in mind there's a difference in fit between the Foil and Cervelo so it's not apples and apples. If I got my hands on an S5 to test, it would be an apples and apples comparison.

Today will probably be my last run with the Foil unless the CdA I get today is wildly different. I have a lot of miles to cover this week and I'm not in the mood to do it on the Foil, I'd rather be done with it.

What should I do with the Fuji? Should I get a longer stem so that we can have a handful of runs to at least compare the Fuji to Foil then change the Fuji over to a negative stem to match the Cervelo and then we can triangulate the results? On my list of to do though, I want to see how aero I can make the Fuji. I'm thinking a - 17 stem and 40cm ENVE ses bars (35mm at hoods). I also need to test the RZRs as well as probably put Veloflex Carbons on the 32's to see how they fare with the same tires.

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[RyanH]

GSC10 Run 7: Scott 2016 Foil on 404s with 23mm Veloflex Criteriums
Recording Device: SRM PC8
Speed Sensor: GSC-10
Tire Pressure: 90F/100R
Beginning Temp: 71*F
Ending Temp: 76*F
Wind: 1-3 mph Omnidirectional (first few laps were from SE then last two/2.5 had mixed winds from N, E and S)
Avg HR: 138 bpm (still recovering from being a sickling)
Avg Speed: 21.4 mph
Avg Power: 223 watts (took it easy today)
Distance Covered: 15.656
Duration: 43:52
Estimated CdA: 0.334
Wind Adjusted CdA: 0.334 (??)
Quality Rating (out of 3): 1 (above average)

Ride Data (Strava)
Google Sheets Aero Data

Notes: Rapha 2015 Pro Team Jersey.

Test Setup:


Chung Method Aero Analysis


Atmospherics (beginning of session)


Comments:
Wind was kind of a mess today. Also, my saddle slipped back about 7mm which I fixed this morning before the run. Didn't make a difference though.