Strange results, please check file

[Mark72]

Hi, I am Mark, and I recently bought a powerpod to be able to follow up on my progress during the year. I only ride for fun, but I am still interested in the numbers.
Last week I did a O&B calibration run, and after a few tries I think it worked (counting up to 50, turn and up to 100).
But when I did my training ride, I got some weird results.
I ride a fully MTB, 29 inch, tire circumference 2250mm with locked front shock.
I paired the PP to a Polar V650.
I use a new B'Twin speed sensor and a new B'Twin cadence sensor, both without magnet, both paired to the PP.
During the ride I saw the powernumbers rise and fall all the time.
It was a mostly (95%) flat ride on asphalt, where I return after about 15km and follow the same route back home. Only the last 2 km don't match the out ride. There are only a few places where I need to slow down or stop. I trie to keep a steady cadence of about 85-95 rpm.
When I uploaded the file to Isaac, I saw the power going up and down, the cadence changing, and the slope bouncing al over.
Today I paired the cadence sensor to the Polar V650 and did a MTB ride. I seemed to me that the cadence sensor worked fine, and gave me a steady signal. Cadence didn't go down on the smooth streets.

Could you please check to see what might be going wrong ?

Thanks

[Velocomp]

Your cadence signal is dropping out all the time, causing watts to fluctuate.

What kind of cadence sensor do you have?

Speed signal is also a bit unsteady. What kind of speed sensor do you have and where is it mounted?

Finally, your slope reading is all over the place...make sure you lockout your front fork.

[Mark72]

First to answer your questions :
The cadence sensor is a B'Twin magnetless sensor from Decathlon, and placed on the left crank.
The speed sensor is also a B'Twin magnetless sensor from Decathlon, and placed on the axle of the front wheel.
I did a MTB ride last sunday, without PP, and linked the sensors to my Polar V650. They both seemed to perform perfectly and gave consisent readings.

Yesterday I did a road ride on my MTB.
I noticed that the powernumbers went up and down like the first time. So, after 14 km I did a new calibration O&B ride.
After that, I returned home taking the exact same route.
You can find both 14 km rides attached. I don't know however how to extract the calibration ride file.
Both my fork and shock are locked out. I tried to pedal as smoothly as possible, and almost never changed gears, to keep cadence (about 90 rpm) and speed (around 24/25 kmph) as a constant relation. Only in the return ride, I changed for a bit to the biggest gear to have a lower cadence in order to have a smoother pedaling stroke.
The cadence sensor does give fluctuating results, but they don't realy match up to the power fluctuations.
The slope however seems to match the power fluctuations.
On two occasions, in the second half of the return ride, I coasted for a few hundred meters, did'nt pedal, and stayed in the same position on the bike, so the bike didn't bounce at all, and still the slope went up and down.
Before I need to buy new sensors, I would like to be sure they're the problem.

[Velocomp]

Your cadence data continues to be very problematic, and your speed sensor is noisy.

Please do the following:

1) remove the battery from your cadence sensor
2) do a new sensor pairing. Your cadence sensor will not be paired (its battery is gone!)
3) you will need to do a new calibration ride, but your power won't vary due to cadence signal problems

Post a short ride file.

I am very puzzled by the large variance in your slope. It will be interesting to see if this problem persists after the cadence sensor is disabled.

[Mark72]

Hi,

I removed the cadence sensor from my bike.
I did a new sensor pairing, and completed a calibration ride O&B on a flat road.
Afterwards I did an O&B ride for 22km total. I tried to keep a steady pace.
My front fork and rear shock was locked out.
But still the slope sensor is giving strange readings during the entire ride.

Any thoughts ?

[Velocomp]

Hi,

I removed the cadence sensor from my bike.
I did a new sensor pairing, and completed a calibration ride O&B on a flat road.
Afterwards I did an O&B ride for 22km total. I tried to keep a steady pace.
My front fork and rear shock was locked out.
But still the slope sensor is giving strange readings during the entire ride.

Any thoughts ?

Please email technicalsupport@velocomp.com I think we should replace your unit; something is clearly not right.