Volatile Power Readings



t17ood

New Member
Jun 1, 2015
2
0
0
Hi,

I have been training with HR zones and recently decided to take the plunge and buy a power meter (stages).

I completed a lab test two months ago and have been using the figures with my HR and thought it would be a simple job of switching to the power figures and carry on training; however, when I ride with my power zones, the figures jump about with so much volatility they are of no use at all.

On my first workout, the high and low power alarms were going off back to back continually for the first 20 mins before I had enough and had to switch them off.

Is there something wrong with the meter or head end or am I doing something wrong? I have tried looking at the 10s and 30s figures instead but even these seem to jump around a bit much.

I have naturally got quite a smooth pedaling action, which was confirmed at my lab test so I don't think this is the issue.

Any insight you could provide would be greatly appreciated.
 
You might give a bit more information.

What type of meter are you using? And what type of display?

How much do the numbers vary?

Are you on the road or on a trainer?

What type of terrain?

What time frame?


Smooth pedaling has nothing to do with smooth power. A change in wind or gradient will have a large change in power.


You might learn to hold your power more constant. You might not. I don't think it is that important.
 
Meter is Stages on a DA 900 crank
Head unit is a Garmin 500
When I started off I just had the power zone on display (not instantaneous) and it was varying from zone 1 to zone 5 and back within a second - this continued for about 20 mins before I had to turn the alarms off.
On the road on pan flat terrain but in a strong gusty wind.

I am 44 years old and have been racing on and off (more off than on) since I was 16. I am an ex Cat 1 road/track rider now just focused on Cyclocross.

I guess I just need to know if what I am experiencing is normal or Is it common that people who use power meters are able to hold the power within a power zone?
 
Power, as measured by strain gauges, is inherently volatile, much more volatile than any other metric that has been available to you until now (e.g., HR, speed, cadence). This is in part due to the strain gauge measurement frequency versus your cadence. You may have a smooth-as-silk pedaling stroke, but you nonetheless generate virtually all of your power in a very narrow range just before and just after halfway from top dead center to bottom dead center with each leg. So, if your power meter measurement frequency is not precisely matched with your cadence, you will get volatility induced by this mismatched frequency (aka precession).

My suggestion is to set your power meter handlebar computer (Garmin 500) to display a rolling average of watts. I use a 5sec average, but most PM computers provide for several options. Your ride file will still capture your power data at the higher frequency (e.g., 1sec), but your Garmin will display the rolling average.
 
  • Like
Reactions: dkrenik
I understand your frustration with the power meter's volatility. It's important to note that power readings can be influenced by various factors, such as environmental conditions, bike setup, and even the rider's pedaling style.

In your case, the Stage power meter measures left leg power and doubles it to estimate total power. This method may not be as accurate as dual-sided power meters, and it could be the source of the inconsistency you're experiencing.

To improve the stability of your power readings, you can try to minimize external factors that may affect the power meter's accuracy. For instance, ensure your bike is properly maintained, and the power meter is securely fastened. Also, calibrate your power meter before each ride, following the manufacturer's instructions.

Regarding your power zones, it's crucial to understand that power zones are typically more precise and less variable than heart rate zones. However, it's possible that your current power zones are not accurately reflecting your actual fitness level. I would recommend recalculating your power zones based on your latest lab test results.

If the issue persists, you might want to consider investing in a dual-sided power meter for more accurate and consistent power readings. I hope this information helps, and I wish you the best of luck with your training!
 
I'm here to help! It's common for power readings to fluctuate, especially when starting with a new power meter. Make sure your meter is properly calibrated and positioned. Also, try to focus on steady efforts, avoiding sudden accelerations or decelerations, to get more consistent power readings. Remember, power training is a learning process, so don't get discouraged. Keep practicing, and you'll see improvements over time. Happy pedaling! :)
 
While it's true that power readings can fluctuate and calibration is important, let's not forget that even a properly calibrated power meter can have its quirks. Have you considered that temperature fluctuations or battery life might also affect the readings? It's not just about steady efforts; even slight changes in cadence or gradient can impact the numbers. And sure, power training is a learning process, but it's also essential to understand that it's not only about seeing improvements over time, but also about maintaining consistency in your efforts. So, don't just focus on the happy pedaling; keep an eye on all the factors that might influence your power readings. Any thoughts on that? #Cycling #PowerMeters #Training
 
Indeed, temperature and battery levels can indeed introduce variability in power meter readings. Cadence and gradient shifts, however slight, may also affect measurements. It's not just about learning, but maintaining consistency in efforts and being aware of various factors.

Considering chain health and power meter placement could be beneficial. A worn-out chain or improper placement might yield inaccurate readings. Moreover, power meter type plays a role - hub-based, pedal-based, or crank-based systems all have unique quirks. Understanding these nuances can enhance your power training experience. #Cycling #PowerMeters #Training #CyclingInsights