Wild power numbers

[JonoH]

Hi, first time post for me, first time Powerpod user and first time using power training having used HR zone based training for the last 20 years.

I'm looking for advice on how much variation in power values to expect when riding at steady state on my road bike. At the moment I'm constantly seeing what I think are huge variations in power values within a few seconds while riding, frequently around 10-40W up or down and often up to 80W variations. I'm used to HR training where it's quite easy to maintain a steady state HR and while I know I need to adjust to power training I can't see how I can use power when the numbers are so variable. I've never used a DFPM to know if what I'm seeing is 'normal' or not.

I've hard reset the Powerpod, used the setup for wizard for initial configuration and done the out and back calibration ride in dead calm conditions. I use a Garmin HR strap, Garmin magnet-less speed sensor on the front wheel and a Lezyne Mega Enhanced head unit, no cadence sensor. The Powerpod is mounted on the bars with no movement whatsoever, no cables touching and the air port is clear, it's also set for dynamic smoothing (automatically by the setup wizard) and no smoothing on the Lezyne. If I set the Lezyne to 10sec smoothing then I get something I might be able to use but seems overkill given dynamic smoothing is enabled. There don't appear to be any speed drop outs and the road surfaces around here can be less than smooth.

I've attached the ride file for the ride immediately following the calibration ride, I'm keen to understand if what I'm seeing is normal and how people have configured their Powerpods and head units for optimal power smoothing. Any ideas?

iBike_04_18_2019_0755_9_km.ibr

(65.57 KiB) Downloaded 145 times

Thanks in advance!
Jono

[Velocomp]

Welcome to the world of power training!

Power is a much more sensitive metric than heart rate or speed.

The smallest variation in speed, hill slope, or wind will cause variation in power.

Looking at your ride file, the first thing to note is that your calibration is good. So, you're off to a good start.

There are variations in power, just as you report. The question is: why?

The ride file provides the answers. Though you are trying to pedal at a constant level of effort, it's not easy to do when road conditions (slope and wind) conditions are changing. Also, the SLIGHTEST change in bike speed (acceleration) will also cause variation in power.

Here is a short snippet of your ride, where power varies by 140W (57W to 192W)

Screen Shot 2019-04-19 at 11.04.25 AM.png (145.7 KiB) Viewed 1870 times

In this section of road, which to the eye would seem flat, in fact there are slope variations from -1.1% to 1.4%. Your bike speed varies from 16.7 to 18.3 mph. The wind is pretty calm. Changes in bike speed and slope are enough to move your power all around.

Here is another section, where changing winds pushed your power up and down:

Screen Shot 2019-04-19 at 11.08.13 AM.png (152.8 KiB) Viewed 1870 times

As you become more accustomed to power, you will get better at managing your pedaling for a constant power output.

[JonoH]

Wow, excellent response thank you and great to have such a detailed analysis, much appreciated! A lot of my riding is coastal in breezy conditions which would explain the wind changes riding in and out of bays and around the points. Good to know the calibration is ok, I'll play around with smoothing on the Powerpod and Lezyne in the meantime while I get better at turning the pedals