MTB measuring problems. Why is measurement not accurate?

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Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

I can not make a setting on PP who giving realistic datas about power on my MTB. I have power meter on my TAX trainer and also have direct power meter on my road bike this two has very similar datas about my FTP etc… I also comparate before last two calibration O&B ride Iin attachment) power with my friend, when we rode together one day , he has direct Garmin two pedal PM, the same kilogram and we had big different in measuring. Approximately 15-20% my PowerPod shower less than this. If I compare with Strava again it is more less.
I have setting PP according the recommendation for MTB CdA=0.49 , Crr=0.0086 , total weight is 92kg. After that I did calibration ride few times and everything was very similar not realistic results .
Please find attachment in this and next message
First O&B ride is only to 50% and back, and after that I have normal ride.
Second O&B ride I did on the same ride because I didn't was satis-fate but this was from 0-50 and back 50-100, after that when device started measuring i did one more time same track like O&B because comparattion , for you.
Las three files is my normal ride after second calibration, maybe this can help you to find where is the problem.
I point out that the PP is properly mounted on the original carrier (holder) and the cables do not interfere.
Please help me to setup this device correct , this data now make confusion on my Garmin devices about my fitness…..
I tied PP on my road bike earlier and the results was very realistic. My wishes is use this device for all of my bikes
Attachments
Ride 3.ibr
(505.86 KiB) Downloaded 145 times
Second calibration ride and ride.ibr
(221.13 KiB) Downloaded 152 times
First alibration ride and ride.ibr
(193.77 KiB) Downloaded 131 times
Last edited by Dusan Turkulov on Sat Aug 10, 2019 6:25 am, edited 1 time in total.
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

Plus two riding file
Attachments
Ride 2.ibr
(389.06 KiB) Downloaded 157 times
Ride 1.ibr
(457.77 KiB) Downloaded 128 times
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: MTB measuring problems. Why is measurement not accurate?

Post by Velocomp »

Your problem is that you are not completing a calibration ride. Either your PP is improperly mounted (likely pointing too high in the air), or something else is not going properly during the ride.

I corrected your profile with the Check Calibration command. Corrected ride 3 file attached.

Load the attached profile into your PP and you should get much better readings. You may still need to adjust this profile for correct weight
Attachments
DusanRide3corr.ibr
(744.04 KiB) Downloaded 143 times
Dusan.ibp
(479 Bytes) Downloaded 144 times
John Hamann
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

Ok, but there is two files. Should I upload Dusan.ibp or DusanRide3corr.ibr ?
There is pictures, tell me what I must correct.
I finished O&B ride and PP started measuring. What I should do next time I have 3 bike and want use for all of this PP
Attachments
IMG_9495.jpg
IMG_9495.jpg (160.54 KiB) Viewed 3844 times
IMG_9494.jpg
IMG_9494.jpg (115.1 KiB) Viewed 3844 times
IMG_9493 copy.jpg
IMG_9493 copy.jpg (109.87 KiB) Viewed 3844 times
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

I uploaded ibp in my profile settings it seems that everything is uploaded. There is all sensors record an the rider weight, bike weight ....but now is different Aero , fric etc....I also uploaded ride 3 and this ride looking like a my usually ride. Tomorrow I will try on the ride. Next step should be my Cyclo Cross bike and Road bike ...
Attachments
868E95CE-6E70-4BAF-822A-EABF5B2773DC.jpeg
868E95CE-6E70-4BAF-822A-EABF5B2773DC.jpeg (213.85 KiB) Viewed 3839 times
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

The letters on the PP are horizontal. is that all right?
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: MTB measuring problems. Why is measurement not accurate?

Post by Velocomp »

Dusan Turkulov wrote: Sat Aug 10, 2019 12:55 pm The letters on the PP are horizontal. is that all right?
Yes, the horizontal orientation of your PP looks good.
John Hamann
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

Hello again. I had ride after correction ant now it looking much better. I had few strange situation, on the flat the power was sometimes on my opinion too high and on up to hill less than normal. You can see this situation between 18 and 24 km. You can see also this on my HR..... power was less then a flat and HR was higher
Attachments
Ride after correctioiBike_08_11_2019_0638_35_km.ibr
(436.27 KiB) Downloaded 150 times
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: MTB measuring problems. Why is measurement not accurate?

Post by Velocomp »

Your ride file looks MUCH better!

What's going on in the section you reference is the effect of your front fork not being locked up.

When you descend your PP adjusts itself for the changed angle happening during descent. When you hit the flats, the fork compression and position changes, and it takes a few minutes for PP to readjust itself for the changed fork position. This is normal.
John Hamann
Dusan Turkulov
Posts: 9
Joined: Sat Mar 30, 2019 5:05 pm

Re: MTB measuring problems. Why is measurement not accurate?

Post by Dusan Turkulov »

OK. That seems logical :D
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