Low Power readings

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spangelsaregreat
Posts: 139
Joined: Sun Aug 13, 2017 2:53 pm

Low Power readings

Post by spangelsaregreat »

Hi

Into week three with the V3 PP. I did a ride today with a couple of friends and noticed throughout the ride that the Power readings appear to be about 50 to 60 watts below what I would have expected. When I was riding on the front (not drafting) my power was well below what I would expect. Where my HR showed I was riding at zone 4 pace power was sitting about zone 2.

For the overall ride I had an average power of 164 with an average HR of 135. If you compare that with a similar group ride just over a week ago I had an average power of 205 and and average HR of 127. I would say todays ride was a bit harder shown in the higher heart rate and I would have expected an average power of around 210 to 220.

Looking at the IBR file in Issac it does look like there is something amiss with the wind as it is showing a tailwind all day. Average wind speed today is about 9mph from the west. It was head and cross wind for the first half of the ride and tail and cross wind for the second half. I have attached the two ride files below. Can you have a look and see if you can identify why the power is low?

Regards
Attachments
iBike_08_01_2019_0803_68_Miles.ibr
(1.15 MiB) Downloaded 174 times
iBike_08_12_2019_0841_63_Miles.ibr
(1.01 MiB) Downloaded 178 times
Velocomp
Velocomp CEO
Posts: 7803
Joined: Fri Jan 11, 2008 8:43 am

Re: Low Power readings

Post by Velocomp »

Your two ride files are at nearly identical bike speeds. Your 8/1 ride is looks like a solo ride; your 8/12 ride appears to be a group ride.

I would expect the 8/12 ride would show much lower watts and show tail wind, because you're drafting most of the time. The amount of tailwind shown is consistent with drafting; however, it isn't clear where you are pulling, because the wind speed is always negative. That might suggest your wind calibration was off for this ride.

It is very difficult to analyze the 812 file, because of the drafting. Just for laughs I adjusted the wind so that your average watts were 203; there is still a tailwind, but not as much. Adjusted ride file is attached.

If your wind port was partially blocked (for example from moisture) this could account for the excess wind speed difference. Other than that I don't know what to say...

By the way: your average HR for the two rides is about the same, and your average bike speed is about the same.

Please post your next solo ride.
Attachments
Spangels_corr_08_12_2019_0841_63_Miles.ibr
(1.01 MiB) Downloaded 157 times
John Hamann
spangelsaregreat
Posts: 139
Joined: Sun Aug 13, 2017 2:53 pm

Re: Low Power readings

Post by spangelsaregreat »

Okay,

Firstly both were rides in a group of 3 riders. In the ride on 8/1 I rode solo after about 40 miles for the remainder of the ride.

In the ride on 8/12 I appreciate that there are times when I am drafting but where I noticed the issue was when I was on the front and not drafting. The power difference was pretty consistent throughout the ride in terms of it being below what I would have expected for the effort I was putting in and comparing it against heart rate.

It was dry during the ride though we did ride through surface water during the ride but the roads were predominately dry. My previous experience of a blocked wind port due to rain is very low power, often 0 watts on the flat, this was not like that. It was consistently displaying power just about 60 watts below what I would expect.

I would note that the two previous rides I have done on this bike since getting the V3 PowerPod the power figures were consistent with what I was getting using the PP V2. On today's ride the power was lower.

I will do a solo ride tomorrow hopefully and see what the number show. If they are still low I will do a new calibration ride and see if that fixes it. Very frustrating.

Regards
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