Aero testing....confused by result

So just use it in resistance mode? Is there a way to use ERG mode without smoothing?

When I did a Chung analysis (6 lap loops), running six different positions my CdA varied as follows…

1 Sitting up
2 On TT bars, hands cupped
3 On TT bars - hand gripping - gap inbetween
4 On TT bars, hands cupped - different wheels (rear disc)
5 On TT bars, hands cupped - different ft wheel
6 On TT bars, hands cupped, shrugged

CdA for position…
1 0.3202
2 0.2646
3 0.2592
4 0.244
5 0.2386
6 0.2377

I’ll be frank, you look much more aero than me.

I was very happy with the analysis. I was able to pick up real difference between positions, wheels and even a shrug. It was not ideal. I had one or two cars pass, there were trees and a bit of a cross wind. And not the smoothest of roads. However I was very very careful NOT to use brakes as I turned. What I did notice, was as I was in a W shaped bowl, coming off the middle, in more aero positions my turn point crept up the hill.

As others have said, its the relative figures that are most useful. Trust me you are far more aero than I am.

I do plan to repeat this some time, and have found a better bowl that has smoother roads.

I hope this helps…

PS Just remembered. The Crr is not what it seems in Golden Cheetah Chung analysis. Apparently it is the average Crr for the wheels/tyres. Not the total. I’ll try and find out where I had an email about this from Chung himself.

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I have vector 3 and Kickr Core. I find the Kickr takes a while to settle down into to match my Garmin pedals. Sometimes 5 -10 mins or so. Not far out. I think it is better when it has warmed up.

but see my other post about my experience of Chung.

Found the Crr piece!msg/golden-cheetah-users/2bZTPxAyQ2U/vkDKCiPyAgAJ This was Dr Chungs reply… in that you put in the weighted Crr of the two wheels. Not the average or the total.

Robert Chung [image] 15/08/2019

On Friday, August 9, 2019 at 2:52:17 PM UTC+2, Philtri wrote:

So, in effect, rather than taking the average between the wheels in the calculation, (or the weighted average) the average is put in the the input value, by the person inputting the values, but that approach is not made explicit, either in the label to the field or the explanation of teh Crr. You can see why I asked the original question now, can’t you.

Hmmm. Sorry for the confusion. Let me see if I can explain.

The total rolling drag is Crr * mass * gravitational constant * speed. If you’re typical, a bit less than half of your total mass is on the front wheel, a bit more than half is on the rear – let’s assume that the front/rear mass is split 45%/55%. Further, let’s assume your total all-inclusive (bike+you+your equipment) mass is 80kg. So, your front tire bears a mass of 36 kg and the rear 44 kg. Gravity and speed are the same for both, so you’ve got Crr(front tire)369.8speed from the front tire, and Crr(rear tire)449.8speed for the rear. You don’t add the Crr of the front and rear – the “system” Crr is the weighted average of the two.

He shows how to turn off the ERG Smoothing in the video, which I strongly suggest that everyone does.

You can use Resistance if you want (which is good power data too), but still worthwhile to kill that crap setting in ERG for whenever you choose to use or in the future.

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Your bike makes hammering sounds, even when you stop pedaling. Maybe look into that.

??? Never noticed it - the trainer is quite noisy, is it that you are hearing?

I think it was a joke. There is some background noise that sounds like someone hammering that start even before you get on the bike.

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Yes, jokes…
At least I think I’m funny!

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