AeroPod, PowerPod and Newton

First up, just want to be clear that accuracy is not in question here, it’s consistency!

A significant part of my riding is my 40 mile daily commute so I tend to go for train heavy race light. Commute on my ally bike with frame bags and sprint a bit, go steady a bit and so on. Then switch to the light plastic bike and hopefully fly.

However, my total weight on a commuted will change by around 3-5kg’s depending on food / liquids / “stuff” that I take in but consume / leave behind and hence don’t take home.

At 5kg that’s over 6% variance in weight so we’ll beyond what I’d think as insignificant. Especially where body weight is concerned.

Given powerpod is heavily dependent on weight, I know the algorithm learns but in the manual I think it said over the first 20mins? But am I worrying about nothing or am I going to see big swings in what is shown as power as the weight changes?

I know I can probably compensate in ISAAC but I use garmin so want live computer and CONSISTENT results. Might be inaccurate compared to some standards but I don’t want my heavy ride in to show one reading when the ride home into a raging F7 headwind may be more powerful but read less due to the weight issue!

Is there a way round it? Or not worth worrying about as this sort of weight change wont make much difference?

A little bit of physics can go a long ways...

1) Weight is important when you are accelerating (sprinting) or climbing hills. In both cases there is a gravitational force you have to overcome (hill force is dependent on slope; acceleration force is dependent on how fast you're changing speed). The magnitude of the force is also proportional to weight. If you're climbing a hill of say, 3% or greater, or if you're accelerating in a sprint, gravitational force is much greater than aerodynamic force; about 80% in our experience.

2) When riding on the flats, at a constant speed, weight is largely irrelevant (it has a small effect on frictional force). Flats/constant speed is a condition where there is no gravitational force; almost all the opposing force is aerodynamic; friction is a distant second.

3) If your riding is a mixture of hills/sprints/flats, a 6% variation of weight will have much less than a 6% variation in overall watts, because weight is relevant only during hills/sprints.

4) PowerPod automatically adjusts during the ride for variations in tilt (slope). Wind calibration is not adjusted, so you'll have no consistency issues when wind conditions change.

I don't know what your commute is like; if you want you can post a ride file. My strong suspicion is this is nothing to worry about.

Cracking! I wasnt overly sure how all the science in the background worked, especially with the weight being one of the profile settings.

Nothing major to worry about is all I wanted to hear!!

Much appreciated.