Gravel bike power readings too high

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BevOutside
Posts: 9
Joined: Wed Sep 04, 2019 8:32 am

Gravel bike power readings too high

Post by BevOutside »

Hi, I've been riding with my PowerPod V3 on my road bike and I think the power readings are quite accurate. They are very much in line with 2 different trainers that I ride. Recently, I added a second profile for my gravel bike, did a calibration then rode a 52 km out and bike ride solo, and the power readings were higher than would be possible for me, given my heart rate and perceived effort. I was on some pavement and gravel, though the readings seemed high on both surfaces.

I guess I need to modify the profile somewhat, though I don't know what to change to improve the accuracy. If it makes any difference, the pod is mounted upside down on my handlebars to avoid cables. I'm running 700x38 tires with a semi-slick tread pattern. I noticed that if I played with the Crr, I can alter the power readings pretty significantly, but how would I know which value to use, if that is indeed what needs to be done?

Any advice would be appreciated. Thanks.
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: Gravel bike power readings too high

Post by Velocomp »

Please post a .ibr ride file and I'll take a look at your settings.
John Hamann
BevOutside
Posts: 9
Joined: Wed Sep 04, 2019 8:32 am

Re: Gravel bike power readings too high

Post by BevOutside »

Here it is:
Attachments
iBike_09_03_2019_1337_52_km.ibr
(618.91 KiB) Downloaded 281 times
Velocomp
Velocomp CEO
Posts: 7267
Joined: Fri Jan 11, 2008 8:43 am

Re: Gravel bike power readings too high

Post by Velocomp »

Your Crr is quite high. I set it to 0.008, a much more reasonable value for gravel riding.

Modified profile and ride file attached.
Attachments
Bev.ibp
(637 Bytes) Downloaded 272 times
Bev_008_09_03_2019_1337_52_km.ibr
(618.61 KiB) Downloaded 281 times
John Hamann
BevOutside
Posts: 9
Joined: Wed Sep 04, 2019 8:32 am

Re: Gravel bike power readings too high

Post by BevOutside »

Thank you. I'll give this a try. I assume that having now sent this profile to my pod, it will automatically detect when I am riding my gravel bike and use the correct profile?
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: Gravel bike power readings too high

Post by Velocomp »

BevOutside wrote: Sat Sep 07, 2019 6:04 pm Thank you. I'll give this a try. I assume that having now sent this profile to my pod, it will automatically detect when I am riding my gravel bike and use the correct profile?
Yes
John Hamann
BevOutside
Posts: 9
Joined: Wed Sep 04, 2019 8:32 am

Re: Gravel bike power readings too high

Post by BevOutside »

I did 83 km with my gravel bike today, the vast majority on a basically straight and flat gravel rail trail. We had a strong headwind going out and corresponding tailwind on the way back.

The pod gave an extremely high reading right at the beginning of the ride, while I was still in my driveway, so obviously not correct. The rest of the ride's power readings seemed quite a bit too low. I noticed that the wind graph doesn't appear to reflect the strong headwind we experienced. It did seem to capture the tail wind on the way back. If anything, it felt like the headwind was stronger, but then it always does, doesn't it? :lol:

Is the pod just not that great at calculating power on gravel, or is it a matter of fine tuning the profile a bit more?
Attachments
iBike_09_08_2019_1222_83_km.ibr
(846.67 KiB) Downloaded 260 times
nickbd
Posts: 2
Joined: Tue Nov 24, 2020 6:01 pm

Re: Gravel bike power readings too high

Post by nickbd »

I've used the PPV3 for a few months with 47 rides but recently have several rides with very high power readings just at the start of the ride. This resolved after I don't removed the PPV3 and it is mounted correctly and does not move. Also I turn the unit off after the ride and then back on just before starting a ride. I've attached 3 rides both starting from the same location (my driveway), one with very high powers at the start 11/22 and one that is typical and normal from today 11/25. In the ride on 11/22 I had stopped pedaling after seeing the incorrect power readings so the cadence was going up and down but make no sense to have 1100W when you aren't even pedaling. I know I can trim off the first few minutes but I haven't had to do this in any of the prior rides. Any help would be appreciated. Aside from this the power readings seem quite OK.

This is a road bike.
Attachments
Velocomp_11_25_2020_1521_13_km_HiDef.ibr
Normal
(351.81 KiB) Downloaded 53 times
Velocomp_11_22_2020_1611_14_km_HiDef.ibr
Incorrect power
(307.58 KiB) Downloaded 52 times
Velocomp
Velocomp CEO
Posts: 7267
Joined: Fri Jan 11, 2008 8:43 am

Re: Gravel bike power readings too high

Post by Velocomp »

nickbd wrote: Wed Nov 25, 2020 6:44 pm I've used the PPV3 for a few months with 47 rides but recently have several rides with very high power readings just at the start of the ride. This resolved after I don't removed the PPV3 and it is mounted correctly and does not move. Also I turn the unit off after the ride and then back on just before starting a ride. I've attached 3 rides both starting from the same location (my driveway), one with very high powers at the start 11/22 and one that is typical and normal from today 11/25. In the ride on 11/22 I had stopped pedaling after seeing the incorrect power readings so the cadence was going up and down but make no sense to have 1100W when you aren't even pedaling. I know I can trim off the first few minutes but I haven't had to do this in any of the prior rides. Any help would be appreciated. Aside from this the power readings seem quite OK.

This is a road bike.
At the end of your ride, click the PP button 5 times. This turns PP off, and keeps any "bad" calibration data from seeping into the device.

If you leave PP attached to your bike between rides and turn it off after each ride, then all should be well.
John Hamann
rtbike
Posts: 1
Joined: Mon Nov 16, 2020 8:02 pm

Re: Gravel bike power readings too high

Post by rtbike »

HI all,

I have a few rides now using the power pod and struggling a bit with the profiles. I am also getting too high numbers on my gravel bike profile as well as super confused at what is going to when Edit a profile and "Extract Profile from Device" and "Send Profiles to Device"

So I have two profiles right now Road Bike Prof #1 and Gravel Bike Prof #2 The road bike profile seems in the ball park with the exception of peddling on slight down hill grades where the number seems a little low, but the Gravel bike has been high by about 100 watts over all, in general I can can't even peddle easy enough to get in zone 2.

After the first ride I found this thread and manually adjusted my gravel profile to a lower Crr number, after the initial out and back ride it was set at something like .025X so I manually adjusted it in Edit Profiles and went for another ride using the same Crr suggested above .0082 and that seemed to bring the watts into the expected ranges.

I switched to the road bike for next ride and the power meter was not pairing with my road bike sensors, I had to return to the Isaac and manually enter the road bike sensor numbers in the Road Bike Profile and send it back to the Device. It seems that what ever bike I ride last over writes both Profile Sensor Ids?

Today I went back to the gravel bike and the numbers where high again.

When I connected to Isaac and Extracted profiles from Device I see my existing gravel bike profile Crr has been over written with a new number .0211 which is too high according to the post above, And when I look at my Road bike profile following the gravel ride today I see Prof #1 sensors are over written with my gravel bike sensor ids again?

I am super confused on how to get this straightened out. There is no doubt this device will work for me if I can understand how to manage these profiles. I actually have a third sensor for the MTB but would like to get 2 working first.

Any help would be appreciated.
Velocomp
Velocomp CEO
Posts: 7267
Joined: Fri Jan 11, 2008 8:43 am

Re: Gravel bike power readings too high

Post by Velocomp »

Please post .ibr ride files from each of your bikes.

We will sort this out for you!
John Hamann
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