PP V2 accuracy?

[KLMSPD]

Hi,

I recently performed a 20 minute FTP test and the results were 254 watts for 20 minutes. I felt that this was high but the device seemed to be working. I did a "Check Calibration" in Issac and it indicated some of profile values would need significant changes.I then made some handlebar bar adjustments that moved the position of the pp so I did a recal and the numbers produced seemed lower but the device seemed to be acting erratic. Sometimes I would be dong what I thought was a large effort and the Garmin was displaying power numbers in 50's or sometimes 0 for a while?? Can you take a look at my ride files and see if there is any dependencies I might address? I've played around abit and now cant see the forest for the trees.
Regards
Karl

[Velocomp]

This is not an appropriate file for Check Calibration, because it is not an out-and-back ride (a requirement to use this feature).

That said, it does appear that your wind calibration is slightly high, causing a constant headwind, and high watts.

I used the "Analyze/Analyze Wind..." command to set average ground wind speed to "0". This took your FTP watts down a little bit, to 226W.

You have a couple of places where watts drop to 0. You will see that in those places there was a momentary reduction in bike speed. These blips have zero effect on your test results. What kind of speed sensor are you using? Where is it mounted?

Corrected ride file is attached.

[KLMSPD]

I am using Garmin sensors. The Speed Sensor is mounted on the front hub. Good to know check calibration is only good on an out and back.
Thx for the check on the ftp file. I wont do another test for a couple of months.
Did you have a chance to look at the second file after the PP was re calibrated because of a handle bar angle change. It is an out and back??

Regards
Karl

[Velocomp]

I am using Garmin sensors. The Speed Sensor is mounted on the front hub. Good to know check calibration is only good on an out and back.
Thx for the check on the ftp file. I wont do another test for a couple of months.
Did you have a chance to look at the second file after the PP was re calibrated because of a handle bar angle change. It is an out and back??

Regards
Karl

Your second ride is an out-and-back, so you can use the check calibration feature.

Your wind speed is slightly low. Corrected profile and ride file are attached.

The corrected profile can be used on your FTP test. My guess from yesterday was pretty good; the O&B profile caused very little modification to my prediction yesterday of your FTP test result (226W to 224W).

[KLMSPD]

**I experienced another issue a few days ago where the device went to zero watts in twice during a ride.
The first time it occurred I stopped and turned the PP off and on then continued. The power data returned then 20 minutes later the same thing occurred this time I just finished the ride. The ride was an out and back so I pieced the first and second parts of the ride together. The file is KLM_PP_intermittent_iBike_07_24_2020_0832_12_Miles - Copy.ibr.

** I thought maybe the PP might have changed positions though I thought I had it pretty tight in the mount so I did a recalibration ride. I would have added the cal ride (Velocomp_07_25_2020_1737_1_Miles_CalRide.ibr) but the Topic would only let me add 3 files??

** Today I went for a ride and did a few intervals. The numbers looked good and the device seemed to be working well. I have a power meter on my mountain bike and a CompuTrainer which I use with Erg videos so I do have some idea what my efforts should feels like. Subjective but it felt right.
Velocomp_07_26_2020_1008_20_Miles.ibr

** At the end of the ride I did a 5 mile out and back. When I checked the calibration with Issac it indicated the cal was off??? The power average went from 120 watts to to 107 watts with the corrected cal. I use these power reading in Training Peaks/Strava/Garmin Connect so when they are this far off my power metrics are off, to fix them is a PITA. Can you take a look and let me know if you can find what might be going on???


Velocomp_07_26_2020_1127_5_Miles.ibr

[KLMSPD]

Bump, No help with this???

[Velocomp]

Bump, No help with this???

When you don't hear from me quickly it's generally because I did not see the original post. I use the "Unread Posts" feature of the forum to search for new posts, and if a post doesn't show up there I probably won't see it...

Your 20 mile ride looks fine.

I caution you (and everyone else) about tweaking the settings. A 5 mile O&B ride is too long; wind conditions can change. More fundamentally, the most important factor in power training is CONSISTENCY, which won't happen if the calibration dials are being tweaked all the time.

Every time Isaac is used for post-ride analysis, the sensor data is reprocessed. Most of the time this works OK, but we have made many advancements in firmware (PowerPod) on-board algorithms. Some of those are more advanced than are currently in Isaac. Unless you see a gross error in wind speed or tilt (neither of which are true for these files) then leave things alone.

On your "mystery" ride, it's looks like your unit got bumped. This caused huge, negative swings in slope, until the unit self-corrected.

[KLMSPD]

Thanks John, The information was very helpful. I had understood longer O&B rides were more accurate but things have changed. I had the original ibike and then the Newton. There was a wind sensor calibration that I guess is no longer used and is calibrated internally?

Regards

Karl

[Velocomp]

Thanks John, The information was very helpful. I had understood longer O&B rides were more accurate but things have changed. I had the original ibike and then the Newton. There was a wind sensor calibration that I guess is no longer used and is calibrated internally?

Regards

Karl

Wow, you're a veteran!

Wind sensor calibration is no longer required. We have are using much more advanced sensor components now.