power stroke interpretation

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kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

power stroke interpretation

Post by kurt »

Dear all;

I have a power pod v3 since mai. In the beginning it was a little bit difficult to install the powerpod on a stable way on my bike but now all works well.
I have also bought the powerstroke option and I have 2 questions:

can you compare left and right with the power stroke? If you look at the both pictures, I would say that they are symmetrical. Does this also mean there is no difference between the right and left leg?
The power stroke data tells me that I loose too much power (I am always in orange or red). However I already tried a lot of things ( saddle lower; higher; more to the back; more to the front; repositioning the cleats) but I don’t see any difference. What can I do more?

If somebody could help with my questions it is much appreciated.

In the attachment you can find the 2 pictures and q Isaac file

Thanks

Kurt
Attachments
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Velocomp_09_21_2020_0752_65_km_HiDef.ibr
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Velocomp
Velocomp CEO
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Re: power stroke interpretation

Post by Velocomp »

What kind of cadence sensor are you using (brand and model)?

What kind of bike computer?
John Hamann
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

Hello;

I use a garmin speed and cadence sensor (Garmin Bike Speed & Cadence Sensor 2 - 010-12845-00).
I don't use a bike computer but my telephone with the app bikecomputer pro.

Best regards
kurt

P.s.: Why should the bikecomputer have an influence?
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

Your ride file reflects a bug in the cadence signal we are investigating.
John Hamann
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

ok, If you need additional info; please let me know
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

Velocomp wrote: Sat Sep 26, 2020 10:53 am Your ride file reflects a bug in the cadence signal we are investigating.
Your ride file has been helpful in confirming a suspicion we've had regarding a bug with the interaction between the Garmin 2 cadence sensor and our firmware.

It appears we have a bug in our firmware.

Once we get the FW fixed you should do another ride. That will be the time to analyze your powerstroke data.
John Hamann
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

ok, no problem, keep me informed
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

hello, do you have an idea when there will be an update? (1 week, 1 month, 3 months, 1 year)

thanks

Kurt
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

Hopefully in the next month.
John Hamann
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

Hello,

How is the update proceeding? Any information, scheduled date?

Thanks

Kurt
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

We are making progress in finding and fixing the cadence measurement bug. It is a very subtle bug but we hope to have something soon.
John Hamann
kurt
Posts: 55
Joined: Wed Sep 23, 2020 1:58 am

Re: power stroke interpretation

Post by kurt »

hello, Is the bug fixed?
thanks

Kurt
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

kurt wrote: Sun Nov 29, 2020 3:39 am hello, Is the bug fixed?
thanks

Kurt
I have sent you an email about this.
John Hamann
RoadWarrior
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Joined: Tue Aug 11, 2020 12:12 am

Re: power stroke interpretation

Post by RoadWarrior »

I'm getting into a similar point here:

Using Garmin ANT+ cadence and speed sensor as well.
Looking at the following picture that is showing a small part of the ride, you can see how scattered the movement is.
But overall it is dominated by too much back/forth movement.
How is this trained? where can there be guides found on how to train this movement.
Image

looking then at the whole ride we can see that the overall movement is less scattered, but still very strong back/forth related.
What makes that back/forth movement so dominating?
I had rides where left and ride was very minimal, less than 0.5cm, but back/forth was up to 1cm.
Image



besides this (i don't want to add a new topic) I'm currently doing quite some training on a Velodrome.
We usually have a lot of wind here and using the powerpod with such a setup I figured that there is quite some delay in the power data that comes to my display:
I use the setting 0s delay on the PP and use a 3s avg on my Garmin.
As you can imaging on a Velodrome you turn into the wind out of the wind. If you follow a plan that tells you ride for this time in Power Zone 3 it is some kind of crucial to receive fast data, else you read measurings from a spot that you passed 100m ago and of course, the faster you ride, the bigger the gap is.
So when I f.e turn into the wind my Garmin, doing 3s avg, is displaying powermeter data from the non-wind part still for like the next 10s. Meaning that for a significant time my data is wrong, same happens of course when I turn out of the wind, and also when I have crosswind, since it is an oval shaped course. And this the whole 1hrs, 2hrs, or how long the training goes. And of course, the faster you ride when f.e. in Zone 5, the worse the offset is.

So, is there any way to shorten this lag?
Velocomp
Velocomp CEO
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Re: power stroke interpretation

Post by Velocomp »

You can't look at PowerStroke over a short time interval. There are not enough data points to calculate meaningful information. This is why your plot looks so scattered.

You need at least 3-5 minutes of data to start getting useful numbers.

Please post your ride file.
John Hamann
RoadWarrior
Posts: 20
Joined: Tue Aug 11, 2020 12:12 am

Re: power stroke interpretation

Post by RoadWarrior »

Hi John,

please find attached a ride file.

As lined out:
Powerstroke: how to decrease back and forth movement.

Using PP in a Velodrome with wind:
Below you can see a picture from my ride on the Velodrome, I go counter clockwise, so the wind comes from above or N-NW.
when I am on segment '1' I have on my Garmin high values, based on a delay from the transmission from PP to the Garmin and then using the 3s average I'm meant to use for the training. In Segment '2', when I already go against the wind again, I still have lower values.
As I said, I have 3s average, but when I ride, the delay until in segment 2 the power value is rising is around 10s after you feel that you turn into the wind. Same is then the delay on the other side when turning out of the wind.
Now doing this in Power Zone 2 is difficult, doing it in Z3, hard, 4 and 5 is impossible to actually control how you have to pedal to stay within the requested Zone since the offset based on the ground speed and the m/s is by far out of anything.
Image
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Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: power stroke interpretation

Post by Velocomp »

It looks like your laps are about 1 minute long.

You have your PP set to 0 sec smoothing; if you're trying to see instantaneous changes in power, this is the correct setting. In this setting, the power being transmitted to your Garmin is IDENTICAL to the power you see in your ride file, with filtering set to zero. Here is one of your laps:
Screen Shot 2020-12-02 at 2.00.56 PM.png
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Your instantaneous power varies from 68 W to 159W, and average is 119W. The instantaneous values last for 1 second only, so with your Garmin set to 3 sec averaging, you won't see these.

It's easy to tell from the wind pattern your loop location. On the headwind portion of this loop you averaged 132W. On the tailwind/return portion it was 106W. You should be able to see this difference on your Garmin; however, these half-loops are only 30 seconds long, you'd have to be looking at your Garmin nearly continuously to see them!

Also, when you go from headwind to tailwind, there is going to be a time delay (caused by Garmin averaging) before you see your watts begin to drop.

If you want to give yourself the best shot at seeing faster responses to your power changes, then set 0 sec on your Garmin. Just note: the power numbers you see may be jumpy.
John Hamann
RoadWarrior
Posts: 20
Joined: Tue Aug 11, 2020 12:12 am

Re: power stroke interpretation

Post by RoadWarrior »

I received the pitot tube last week and added it.
Saturday I had a nearly wind-still FTP ride on the curse can't complain on that, yesterday was also ok, today I had another training on the curse with more wind (~15km/h WNW) and the info on the screen was more stable, less flaky like on other days with similar conditions.
To me it seems, and I did read this before, that the pitot tube helps for better measures in crosswind, and in Power Zone 4, doing 35km/h on a 500m long round curse you reach quite fast changing conditions and 2x crosswind. So for now, this seems a big improvement with the pitot tube.
Riding down the road in one direction over a long time, there are no such big differences, but as it seems an open air velodrome with wind has his moments.
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