Not sure if my powerpod is properly setup

[qillen2013]

Hi,

I am a new user of powerpod. I have calibrated my ride 2 days ago and so far have mixed result of my power output. I did a ride this morning and am requesting your kind help to help me review my ride file. Please let me know if my powerpod is calibrated properly.

Additional info on me is
- Height 170cm
- Weight 69kg
- Bike : Mini Velo with 20 inch wheels. My wheel profile is 20 X 0.91. Am using schwalbe one tires
- Ride position - mostly upride and not aero.
- Using garmin 820. Speed and cadence sensors are Garmin Magnetless sensors


Please help me out as I am not sure if i can trust the power output at the moment.



Thanks
Best Regards

[Velocomp]

Here is what I look at in a ride file to see if a PowerPod is properly set up. I will go through my process in detail, so it might help others, too:

0) In Isaac I use the Edit/Edit Profiles command, then click "Extract from Ride File" to get your profile information. I click on "Wireless IDs" to find out the kind of sensors you are using. You have separate speed and cadence IDs, so most likely you are using magnet less sensors. That is good.

1) I look at wind speed vs bike speed (blue and white graphs). Unless a rider is riding in strong winds, or drafting in a peloton, wind speed in blue should "hover" around bike speed in white. Yours does this, so this means a good calibration. I check your wind scaling factor in Edit/Edit Profiles/Advanced. Your factor is 1.771, which means you have customized the wind scaling. This is why your calibration is so good!

2) I look at the total weight. Yours is 172 pounds, so you did use Isaac to set up your PP. This is good, too.

3) I look at CdA and Crr. These values are different from the default values, but since you used Isaac to set up your weight, this makes sense. The values shown are typical for someone of your weight, so this is good, too.

4) I look at the first 8 minutes of the ride, examining power, elevation and slope. In your case, power was zero, even though you were pedaling. I notice you were riding on the flats (elevation change is only slightly downhill) but slope (red) is really negative (-10%), indicating that your PP was pointed more down, compared to its position on the previous ride. When pointed "downhill" this will cause zero watts (if it were pointed up you'd have really high watts). Try to attach your PP in the same rotational position at the beginning of each ride.

5) After 8 minutes PP automatically corrects the tilt problem and your power readings become normal.

6) I notice some "spikes" in your speed. I set the graph filtering (in the top right menu of Isaac) to 0:00:00 (no filtering), so that I can see if your sensors are operating correctly (zero filtering will reveal if there are speed dropouts).

7) I do see some possible evidence of speed dropouts, but normally dropouts appear as straight vertical lines, where speed goes abruptly to zero, then reappears. Yours are not like that; their shape appears to be more possibly the result of applying brakes.

8) However, at a few places, such as mile 10, I see speed drop to zero. Perhaps you stopped riding...

9) Finally, I look at power vs speed. When on the flats, riding at 20 mph, your power readings, in watts, should **approximately** be 10x the speed of the bike. THIS IS NOT A HARD AND FAST RULE. But, in your ride your power is about 8 times your bike speed (you have a lower CdA and your speed is lower than 20 mph) so I think that is fine, too

I think your PP is working great! However, if your speed sensor is attached to your rear hub, then put it on the front hub to eliminate any possibility of speed dropouts.

[qillen2013]

Hi John,

Thanks for the detailed analysis. My speed sensor is on my front wheel so i guess my powerpod is working well. I have learnt alot from your analysis and i am sure others reading this post will too. I feel more confident of my powerpod now:) Will proceed to do another FTP test on my next ride

Thanks for your help
Best Regards
Charles

[drashkum]

Here is what I look at in a ride file to see if a PowerPod is properly set up. I will go through my process in detail, so it might help others, too:

0) In Isaac I use the Edit/Edit Profiles command, then click "Extract from Ride File" to get your profile information. I click on "Wireless IDs" to find out the kind of sensors you are using. You have separate speed and cadence IDs, so most likely you are using magnet less sensors. That is good.

1) I look at wind speed vs bike speed (blue and white graphs). Unless a rider is riding in strong winds, or drafting in a peloton, wind speed in blue should "hover" around bike speed in white. Yours does this, so this means a good calibration. I check your wind scaling factor in Edit/Edit Profiles/Advanced. Your factor is 1.771, which means you have customized the wind scaling. This is why your calibration is so good!

2) I look at the total weight. Yours is 172 pounds, so you did use Isaac to set up your PP. This is good, too.

3) I look at CdA and Crr. These values are different from the default values, but since you used Isaac to set up your weight, this makes sense. The values shown are typical for someone of your weight, so this is good, too.

4) I look at the first 8 minutes of the ride, examining power, elevation and slope. In your case, power was zero, even though you were pedaling. I notice you were riding on the flats (elevation is only slightly downhill) but slope (red) is really negative (-10%), indicating that your PP was pointed more down, compared to the previous ride. This will cause zero watts (if it were pointed up you'd have really high watts). Try to attach your PP in the same rotational position at the beginning of each ride.

5) After 8 minutes PP automatically corrects the tilt problem and your power readings become normal.

6) I notice some "spikes" in your speed. I set the graph filtering (in the top right menu of Isaac) to 0:00:00 (no filtering), so that I can see if your sensors are operating correctly (zero filtering will reveal if there are speed dropouts).

7) I do see some possible evidence of speed dropouts, but normally dropouts appear as straight vertical lines, where speed goes abruptly to zero, then reappears. Yours are not like that; their shape appears to be more possibly the result of applying brakes.

8) However, at a few places, such as mile 10, I see speed drop to zero. Perhaps you stopped riding...

9) Finally, I look at power vs speed. When on the flats, riding at 20 mph, your power readings, in watts, should **approximately** be 10x the speed of the bike. THIS IS NOT A HARD AND FAST RULE. But, in your ride your power is about 8 times your bike speed (you have a lower CdA and your speed is lower than 20 mph) so I think that is fine, too

I think your PP is working great! However, if your speed sensor is attached to your rear hub, then put it on the front hub to eliminate any possibility of speed dropouts.

That's some great insight John on what you do....I am learning a lot