Wind Calibration

[madmaxx]

Hi Guys, need some advice;
Before i set out for a ride in the morning say 630am, i turn the ibike on and the auto wind kicks in. After riding for about 2 hours and i return home and i switch to "Wind display" it reads -3 to -5 i double checked by turning the bike 180deg but it still reads the same. I was careful to calibrate the wind by cupping my hand on the RWS (not touching or plugging the end) at the beginning. I'm curious that the wind calibration affects the interval workout i do at the later part since if the wind senses a negative number then it might think that im riding downwind and it projects a lesser power output thus forcing me to produce more effort than necessary..

has anybody experienced this? is this because of the change in air density due to the change in temperature? ex. from 26degC to 30deg C

[travispape]

has anybody experienced this? is this because of the change in air density due to the change in temperature? ex. from 26degC to 30deg C

It is due to the effect temperature has on the sensor & amplifier rather than its effect on air density. We are getting everything we can out of the wind sensor and there is a factory temperature calibration that removes most of the temperature dependence; however, as you have seen there is still some temperature dependence left. So it is a good idea to let the unit soak in the temperature that you will be riding in for at least 15 minutes (out of the sun!) and then do the wind cal before hitting the road. It takes some time for the interior of the iBike to reach temperature.

Note that you can fix any wind cal problems due to temperature dependence in the iBike SW. If your solo ride has an O&B, laps, or ends where it begins (e.g. your house), then the "Tools -> Analyze Route..." function will automatically handle the correction. If your ride was a commute, you can use the "Tools -> Analyze Wind..." function to set the avg headwind (or a negative number for tailwind) to what it should have been based on the day's weather and your bearing against the wind. If it was a calm wind day, the average wind would typically be a small negative number to take into account the net effect of a small tailwind caused by traffic. I typically see something around -0.5 mi/h average wind.

Travis

[madmaxx]

Thanks,
But im more concerned about the effect it would have during the actual usage of the PM, would a -3 wind translate to a wrong readout on power? ex. during a 3 x 20min steady state interval with 10min rest in between from the first interval to the last there's already about an hour difference and if during the last interval the wind is already reading -3 am i actually putting out more power than necessary because of the lower power reading?

fyi, i take my bike out of the house 15mins before i ride but the temperature from 6am to 8am increases rapidly from 26deg C to 28-29ish deg C

[racerfern]

Thanks,
But im more concerned about the effect it would have during the actual usage of the PM, would a -3 wind translate to a wrong readout on power? ex. during a 3 x 20min steady state interval with 10min rest in between from the first interval to the last there's already about an hour difference and if during the last interval the wind is already reading -3 am i actually putting out more power than necessary because of the lower power reading?

fyi, i take my bike out of the house 15mins before i ride but the temperature from 6am to 8am increases rapidly from 26deg C to 28-29ish deg C

FWIW, I do similar intervals with significant temperature changes due to my location and time of day. So, I do a wind offset when I set out on the ride. I also do a wind offset after warming up when I start my intervals. I also note the temperature. If there is a rise or drop of 5 degrees F or so, then I will do another offset during the rest interval. That way I know my goal numbers are really what they should be. It take 15 seconds to to a wind offset and it's well worth the time.

[cjonbike]

What is your trick to doing a wind offset on the road? I always have wind!!! I have tried but with not a lot of success.

Thanks for your tips!

[racerfern]

I try to face into the wind and cup my hand closely without touching the iBike. IF, when you press and go to setup and immediately see a number such as -5 or +5 then I proceed with the wind offset procedure, IF I immediately see a number such as -1.5 or +1.5 then I exit setup and continue my ride. If I have time, such as at a traffic light then I will do a wind offset check. However, I do note the temperature since if the temp hasn't changed, the wind offset hasn't really changed either.

[cjonbike]

I Thank you Fernando. I have not had the luck with cupping my hand over the ibike, but I probably was not facing into the wind either, will pay more attention.

Again Thank you!

Chris

[madmaxx]

Thanks Fernando, appreciate the inputs...

[bdensel]

has anybody experienced this? is this because of the change in air density due to the change in temperature? ex. from 26degC to 30deg C

Note that you can fix any wind cal problems due to temperature dependence in the iBike SW. If your solo ride has an O&B, laps, or ends where it begins (e.g. your house), then the "Tools -> Analyze Route..." function will automatically handle the correction. If your ride was a commute, you can use the "Tools -> Analyze Wind..." function to set the avg headwind (or a negative number for tailwind) to what it should have been based on the day's weather and your bearing against the wind. If it was a calm wind day, the average wind would typically be a small negative number to take into account the net effect of a small tailwind caused by traffic. I typically see something around -0.5 mi/h average wind.

Travis

Travis,

Just installed my Newton and did a 1-hour ride to determine FTP. Wind was mild and consistent and course was a loop. As you mentioned previously, my average wind was -0.5, likely due to traffic. My issue is that in Analyze Route, if I check that ride started and ended in the same place, ISAAC changes the average wind to 0.0 and my average watts increases by 11 watts. So my question is whether or not to indicate the ride started and finished in the same place? I know 11 watts is not a big deal, but it is to me when determining FTP. Thanks

[travispape]

My issue is that in Analyze Route, if I check that ride started and ended in the same place, ISAAC changes the average wind to 0.0 and my average watts increases by 11 watts. So my question is whether or not to indicate the ride started and finished in the same place? I know 11 watts is not a big deal, but it is to me when determining FTP. Thanks

Actually, probably the best thing to do is leave "Ride Ended Where it Began" selected and check the box for "Wind Changed". What this will do is allow any elevation correction that needs to be made due to atmospheric pressure changes to be made, but by checking the box for wind changed your wind data will be left as is. With the Newton's improved wind sensor, you should find that the wind data is good as measured on the bike and does not need to be adjusted. Checking the "wind changed" box will allow the wind data to be left alone.

Travis