Hi John
ive done the out and back calibration and two rides post that ive noticed that with a tail wind or a cross/tail wind the power is high, far higher than it should be.
i have the out front mount of yours. i have attached the rides, could you please advise how to fix this, i need as accurate power numbers as possible, as im due both a fatigue and a FTP test when i can confirm the pod is working properly
the 28 mile ride the areas of concern are the 6 to 8 mile period and the 12 to 14 mile period,
in the 64 mile ride its the 35 to 40 mile period thats far too high.
thanks Ian
Power is reading too high with a tail wind
Power is reading too high with a tail wind
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- iBike_02_27_2017_1110_27_Miles.ibr
- (263.82 KiB) Downloaded 245 times
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- iBike_02_25_2017_0743_64_Miles.ibr
- (703.58 KiB) Downloaded 268 times
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- iBike_02_24_2017_1704_3_Miles_CalRide.ibr
- (50.3 KiB) Downloaded 274 times
Re: Power is reading too high with a tail wind
The 35 to 40 mile portion of your 64 mile ride is on a downhill. If you go into any kind of tuck on downhills, and pedal, then PP will read high.
I would not do any kind of FTP testing on a downhill...
On your 27 mile ride, the areas you note show sudden shifts in wind. For example, around mile 12 the wind abruptly changes from a 5 mph tailwind to a 5 mph head wind! If this is really happening then I think PP is giving you accurate power.
When I do FTP testing I try to pick a day with consistent wind from the same direction. In these ride files your wind is going all over the place and that makes holding a constant level of power quite difficult.
By the way, I do think your PP is properly calibrated...
I would not do any kind of FTP testing on a downhill...
On your 27 mile ride, the areas you note show sudden shifts in wind. For example, around mile 12 the wind abruptly changes from a 5 mph tailwind to a 5 mph head wind! If this is really happening then I think PP is giving you accurate power.
When I do FTP testing I try to pick a day with consistent wind from the same direction. In these ride files your wind is going all over the place and that makes holding a constant level of power quite difficult.
By the way, I do think your PP is properly calibrated...
John Hamann
Re: Power is reading too high with a tail wind
Whilst i acknowledge the 35 to 40 mile part is on a downhill, i wasnt in a tuck. i was arms bent over the hoods which is my normal riding position and pedalling in top gear. i know that it didnt feel like 450 watts. is that not a calibration issue?
its the same for the crosswinds, they are normal here where i am in NZ, there will always be some wind, so does that mean that the power will always read way too high with a cross/tail or tail wind?
i want to see this system work, is there any tweaks i can do in the setup?
cheers
Ian
its the same for the crosswinds, they are normal here where i am in NZ, there will always be some wind, so does that mean that the power will always read way too high with a cross/tail or tail wind?
i want to see this system work, is there any tweaks i can do in the setup?
cheers
Ian
Re: Power is reading too high with a tail wind
Hi John
can I please get some clarity around the power numbers from the power pod as follows;
are you confirming that anytime I pedal down hill the number will be higher than what the actual number is?
will a cross wind that is side on to the power pod give inaccurate readings due to the fact that it will pick it up as sometimes a head wind and sometimes a tail wind?
the concern I have is I am trying to keep a tight control of my CTL and ATL, if their are higher readings than what is real then that will affect the accuracy of balancing CTL/ATL. on every ride where I pedal downhill it is showing 350 watts for a heart rate of 125bpm, yet when it is flat or uphill and I am doing 200 watts for the same heart rate?
cheers
Ian
can I please get some clarity around the power numbers from the power pod as follows;
are you confirming that anytime I pedal down hill the number will be higher than what the actual number is?
will a cross wind that is side on to the power pod give inaccurate readings due to the fact that it will pick it up as sometimes a head wind and sometimes a tail wind?
the concern I have is I am trying to keep a tight control of my CTL and ATL, if their are higher readings than what is real then that will affect the accuracy of balancing CTL/ATL. on every ride where I pedal downhill it is showing 350 watts for a heart rate of 125bpm, yet when it is flat or uphill and I am doing 200 watts for the same heart rate?
cheers
Ian
Re: Power is reading too high with a tail wind
Sorry, I have been really busy with other things and am finding it difficult to respond quickly.
On the downhill on your second ride (mile 36-40), I do not see 450 watts. Your average is 265W, and in the section around mile 38, where you are hammering in top gear, it's 365W.
It is true that, on downhills, the power signal will be "noisier" due to speed. Also, any small change in any parameter will cause large changes in watts.
But looking power data over short periods is not meaningful.
You don't have a heart rate data, so I can't tell if you are working as hard in the downhill as in the climbs. But your data shows clearly that you are capable of sustaining high levels of power.
I do suspect that your power is somewhat high on this severe downhill, but I don't think it is off nearly as much as you think.
On the downhill on your second ride (mile 36-40), I do not see 450 watts. Your average is 265W, and in the section around mile 38, where you are hammering in top gear, it's 365W.
It is true that, on downhills, the power signal will be "noisier" due to speed. Also, any small change in any parameter will cause large changes in watts.
But looking power data over short periods is not meaningful.
You don't have a heart rate data, so I can't tell if you are working as hard in the downhill as in the climbs. But your data shows clearly that you are capable of sustaining high levels of power.
I do suspect that your power is somewhat high on this severe downhill, but I don't think it is off nearly as much as you think.
John Hamann