Powertap and Newton power not matching up

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Aaron
Posts: 31
Joined: Thu Apr 14, 2011 7:14 pm

Powertap and Newton power not matching up

Post by Aaron »

I am borrowing a friends Powertap for a few weeks and wanted to take the opportunity to compare with my Newton 4. I did a 50 mile ride today and the power from each is pretty different. Would be great to know if something is up with my Newton 4 profile/calibration.

Yesterday in anticipation of getting the Powertap, I did a few out and back rides as I thought my wind scaling was off. I am including two out and back rides as well. I used the check calibration feature of Isaac on each of these files and changed the wind scaling from 1.599 to 1.010. With that change I did the ride today.

Any thoughts would be great.

thanks,
Aaron
Attachments
05_13_2016_0643_2_Miles Out Back 2.ibr
(66.33 KiB) Downloaded 378 times
05_13_2016_0637_2_Miles Out Back 1.ibr
(66.24 KiB) Downloaded 362 times
iBike_05_14_2016_0848_52_Miles.ibr
(575.52 KiB) Downloaded 366 times
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Powertap and Newton power not matching up

Post by Velocomp »

Take your 52 mile ride and use the Analyze/Check Calibration feature. Use the DFPM data for fine tuning.

You'll find that your wind factor is wrong, and that once it is corrected, the two units match closely.

Send the corrected profile to your Newton and you will get better results.
John Hamann
Aaron
Posts: 31
Joined: Thu Apr 14, 2011 7:14 pm

Re: Powertap and Newton power not matching up

Post by Aaron »

Followed your suggestion and it did have a big effect on the wind scaling. Picture attached.

Question- I'm wondering why the out and back rides I did the previous day did not set the wind scaling correctly? Any ideas?

Aaron
Attachments
Screen Shot 2016-05-14 at 7.49.17 PM.png
Screen Shot 2016-05-14 at 7.49.17 PM.png (33.1 KiB) Viewed 10443 times
Aaron
Posts: 31
Joined: Thu Apr 14, 2011 7:14 pm

Re: Powertap and Newton power not matching up

Post by Aaron »

Would be great to know why my previous out and back rides did not yield accurate wind scaling values. I will need to give the power tap back and want to have a solid procedure if I need to change the position of the Newton or something like that.

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

Re: Powertap and Newton power not matching up

Post by Velocomp »

I can't comment on that because I do not know the circumstances.

You do have a very old Newton, one of the very first ones manufactured. Age itself is not a factor (the sensors don't get old) but like everything electronic, the newer it is, the better it is.
John Hamann
Aaron
Posts: 31
Joined: Thu Apr 14, 2011 7:14 pm

Re: Powertap and Newton power not matching up

Post by Aaron »

Circumstances.... I rode the bike for about 45 minutes. Then I I did a WindCal out of the wind. Then I did two out back rides on the same stretch of rode. Used the lap function to mark each out back ride. Then split each out back ride as a separate file which I shared in this thread.

So, if you were to recommend buying new, do you recommend upgrade process or buying new?

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

Re: Powertap and Newton power not matching up

Post by Velocomp »

The Newton 6 upgrade will be the most cost effective. You'll get current firmware (you are using the original FW) and you'll also get an upgraded case design, which is better at "reading" wind.
John Hamann
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