Wind scaling

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andrewlees
Posts: 31
Joined: Tue May 07, 2013 1:43 pm

Wind scaling

Post by andrewlees »

I have a quick question about wind scaling. If you're in profile, and a wind cal is required for whatever reason, is that wind scaling value applied to the profile or the unit?
Thanks.
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racerfern
Posts: 1356
Joined: Fri Jan 11, 2008 12:47 am
Location: Baldwin, NY
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Re: Wind scaling

Post by racerfern »

The short answer is it's applied to the unit.

The longer answer is there are two "wind" names.
Wind Scaling is the math needed to balance out a true out/back ride so the wind speed equals zero. This number is stored in the profile and is "usually" in the .9 to 1.5 range if the iBike is on the stem. It gets determined in the cal ride.
Wind Offset is the difference in day to day atmospheric conditions that affect how much wind pressure the unit sees. For instance temperature and atmospheric pressure will affect how the iBike sees "X" wind. Nowadays the Newton doesn't even need a wind offset change, it handles just about any conditions automatically. This Wind Offset value is stored in the unit.

So if you change from profile 1 to profile 2, the Wind Scaling will be whatever was stored in the profile but the Wind Offset will remain the same since it is in the unit.
Fernando
josedeya
Posts: 6
Joined: Thu Jul 24, 2014 8:37 pm

Re: Wind scaling

Post by josedeya »

Hi,I did a ride and found a lot of difference in the power meassure while riding head-wind versus tail-wind, even the perceived effort is more or less the same
The figures are:
3 minutes ride, Power 309, Aero 233, Speed 37, Wind 39.7, slope 0.02
2 minutes ride, Power 225, Aero 132, Speed 35.7, Wind 30.4, slope 0.25

I was trying to ride at 300 watts and was impossible to do it during the 2nd part after 1 minute of pause, Is this normal?
My feeling was that riding uphill and tailwind the power meassure was lower compared to the 1st one, even my effort seems preety similar.

Any clue? I was reading this wind scaling and maybe something is not good there...

Attached the riding file, the segments are between 35,8km of the ride and 37,9 km

Thanks! And best regards!!!
Attachments
iBike_2014_08_09_1420_80_km.ibr
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Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Wind scaling

Post by Velocomp »

It looks like the first 30KM of your ride was in a group; is this correct?

At KM 36.1 it looks like you begin an interval that goes for about 2 minutes. Your power in this interval is 224w, you have a very slight (5km/h) tail wind, and there is a small uphill (0.15%). Your bike speed is about 35.1 Km/h

At KM 37.9 there is another interval, this one about 1 minute long. You averaged 240W in this interval, at a speed of 37.5 KM/h, but you were on a slight downhill (-0.32%). You still had a slight tailwind of -3Km/h. Note that the power was about the same, but your bike speed was higher, due to the downhill slope.

Is it possible that you are looking at max watts, when the meaningful metric is average watts? Maximum watts can be very high, especially when acceleration is included. Note that your second interval had a big watts spike at the beginning of the interval.

Your Newton is working fine, as is your training :-)
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Screen Shot 2014-08-10 at 9.19.20 PM.png
Screen Shot 2014-08-10 at 9.19.20 PM.png (291.94 KiB) Viewed 4329 times
John Hamann
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