Interesting discussion - where is the drag center?

I don‘t know many publications addressing this topic. If I interpret correctly the results from the „ring of fire“ experiment from a Dutch group, the drag center is quite low in TT position, i.e. somewhere between the crank axle and the base bare hight.

Thanks, yes, you got my meaning and not what I literally wrote. Enjoying the blog post now...

E

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

How are your tests going so far ? It would be nice if people shared their experiences like pyf above

What's the lead time you all have seen on the Notios?

I'm waiting out for a couple days after the standard "x" business days, just wondering.

I was asking as I have a lead on a Garmin to talk to it and don't want to leave a person hanging on getting it. I wanted to get it in my hands and working with the app before settling on the Garmin. Didn't know how long to tell the guy before I have it.

I have no idea since I never actually purchased one and I haven't used one in a long while

However I do know they are on FB and answer questions quite quickly

There are very few people actually posting data and results.
Maybe ping the ones that have tested to see if it is going to meet your needs.

It's going well. I calibrated the unit and then tested some jerseys I knew to be a certain CdA delta over each other around a 400m empty track and got similar results. I'm not confident in day over day testing yet however, all my conclusions are drawn from A/B same day testing only so far.

It's a really cool piece of tech, not sure how it differs from the AeroLab but I'm still getting to know the Notio and Golden Cheetah. It could be useful for my fit business to validate certain gray area changes for people who care about 5w differences like Kona Qualifiers and TTers.

E

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

I got mine fairly instantly. You're welcome to come see it if you like.

E

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Hi rruff,

Sorry for the late answer.

Below is an example of an out & back (1km out + turnaround + 1km back), only the tests sections are included (turnaround excluded of course). The average wind speed for out & back never is exactly zero, but it's never insanely positive or negative either ;-) . First blue selection is 1km out, middle is turnaround, second blue selection is 1km back. Summary on the left is average of both out & back intervals.

Is the wind distance-averaged? A 1.3 kph bias isn't weird for one lap, but what do you get for 10 or 20 laps? And what is your protocol?

I think it would be better to determine the deviations during a single session when you are trying to keep everything constant. Then repeat this test on several different days when conditions are different.

Is that better for you over 16 tests (16 out & back so 32 x 1km overall) ?

Right, I've done that, and over many many runs on many days I take an average, which usually tracks with the CdA delta on individual days. Total CdA is often different, even though the device is supposedly factoring in Rho differences each day. At any rate, a work in progress.

E

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

It's great you are taking the time to learn it and the s/w before taking on testing customers.

Do you plan to always test on your 400m track ? If not, make sure including hills is part of your learning process. Altitude and wind are the two hardest nuts to crack. At least on the track you only have 50% of the challenges :-)

Yeah, I've done that, too. You can learn a lot by looking at fit, misfit, and patterns in misfit.

Thanks, that affirms my instincts.

E

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

You get an average windspeed of >+1.5 kph for out-back runs? Shouldn't that be zero?

I'd be surprised if the bike+rider was that low. Legs *are* a big part of body drag but still...

In theory... YES ;-) .

In practice :
- when doing 3km tests on a 200m indoor track with same start/finish position for every test (after cutting to remove the first 150m and the last 50m as to not include the influence of pushing the lap button on the Garmin computer) I've recorded between +0.1km/h and -0.3km/h.
- when testing outdoor, since my out & back is slightly uphill/downhill (+6 meters over 1km/h on way out, and -6 meters of course on way back) but thanks for your comment as you made me think again about that important topic. The graph I imported yesterday was wind speed averages over all the out & back tests with a calibration factor of 1.39, which was the (factory) calibration that was making sense in term of CdA but like I said before the out & back tests with sensor on the side of the base bar report calibration factor to be input around 1.34 which tend to correct wind speed but screws CdA a bit (about 0.02 high). With that in mind here is the same graph as yesterday so for the exact sames tests when I change the calibration factor to 1.34.





Which makes me wonder (Marcag ?) : should I switch the calibration factor and use the recommended one for each out & back test ? Or use the one that works best on average on a particular day where I test and keep the same calibration factor for all the out & back tests in the Golden Cheetah analysis ?

If that is distance-averaged wind, and you are riding on the same part of the road for out-back, then your runs should be suitable for calibration... and they should average to zero.

Is the sensor located the same for indoor and outdoor testing?

As you know I am not using the same device as you, but I do have some of the challenges you do.


I don't use an out and back exclusively. I do look at the out and back (if present) as one parameter. Trying to net 0 would work well if wind are "well behaved". But they are rarely well behaved around here. If I tried to net 0 every out and back I'd get quite varying numbers (depending on the weather conditions) and it would insert far more error and variance in runs.

I personally would keep the calibration constant for the entire session. If you have the ability to analyze and adjust post ride, I would do that. I think the ability to analyze/adjust is still in the product. It was way back when.

I find my device is not nearly as sensitive to position change as people imagine. Yes, if you go from just under your hands to the left brake, there will be a huge difference. If you plan huge cockpit changes, adjust the test accordingly. But a new factor for each test will lead to errors IMO.

I messaged them this week on FB and they said they'd drop it in the mail. Still no tracking # and I ordered the 27th.

Are people making custom mounts to get it more out front using a rod? Any pics of that in action. I'm pretty handy with stuff like that.

Some of these devices have accelerometers/gyroscopes in them. Put them too far out on a rod and you may introduce vibration they weren't designed to account for. You may want to ask their support team.

You definitely *don't* want to force wind to cancel on every run, and you *do* want to use the same calibration for the whole session, and adjusting the cal factor after the session (using your runs as the calibration) is a very good idea, IMO. Of course your runs need to be such that you'd expect wind to cancel.

Hi all,

I bought the Notio recently and have used it for some sessions now. Looks to me like a have some testing and learning to do this summer...

I tried to do some testing the other day in a 1,5% - 2% downhill section on approx. 1km. My thought was to ride in high speed without putting down to much power.

When analyzing in Golden Cheetah, I see that the CDA curve is gradually increasing in during each run. Starting from 0,10 and ending runs in 0,30. Is it any logical reason to why this is happening, was expecting a more consistent CDA around 0,22 throughout the run. The average CDA on each run seems to be around what I expected though.

There could be a couple of reasons, but I would look first at wind. Is it constant during the test or is it decreasing as speed increases ?