Average Watts Way Off

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BruceK
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Location: Regina, Saskatchewan

Average Watts Way Off

Post by BruceK »

I have set up my iPro Gen III on my time trial bike (on a stem mount). The unit has been set up and several ride calibrations have been done. However, my average wattage is way too low on all of the rides I have been on. I am no longer confident that the settings are proper and/or the unit is simply not working right. Perhaps the airflow to the unit is being disturbed by positioning it on the stem (the only decent place to mount it on my TT bike) - I just do not know. Attached is a file (with merged GPS data) from my ride today. Any help and/or suggestion(s) would be appreciated. Thanks.
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iBike_08_05_2013_1013_40_km.csv
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racerfern
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Re: Average Watts Way Off

Post by racerfern »

You'll have to upload the ibr file. CSV files can't be opened in Isaac.
Fernando
BruceK
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Re: Average Watts Way Off

Post by BruceK »

racerfern wrote:You'll have to upload the ibr file. CSV files can't be opened in Isaac.
As requested. Thank you for your help. BTW. I have adjusted the data via "Repair ride for bad tilt cal" and it seems the wattage is more realistic given the speed(s) and road grade(s). However, it would be nice to get an experienced person (such as yourself) to look at the data. Thanks again!
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iBike_08_05_2013_1013_40_km.ibr
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racerfern
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Re: Average Watts Way Off

Post by racerfern »

You have a serious issue with your wind scaling. At .3 it's ridiculously low. Your tilt appears to be off at initial glance, however the drop in the first 5 minutes is not all that much. Yes, you should check your tilt but far more importantly check your wind scaling.

Basically, take a look at the speed/wind graph and you have a constant tailwind and a significant one at that. Either the wind sensor is blocked with something or your profile is WAAYYY off. Please take the time to do a proper cal ride or upload a calride so we can have a look.
Fernando
BruceK
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Re: Average Watts Way Off

Post by BruceK »

racerfern wrote:You have a serious issue with your wind scaling. At .3 it's ridiculously low. Your tilt appears to be off at initial glance, however the drop in the first 5 minutes is not all that much. Yes, you should check your tilt but far more importantly check your wind scaling.

Basically, take a look at the speed/wind graph and you have a constant tailwind and a significant one at that. Either the wind sensor is blocked with something or your profile is WAAYYY off. Please take the time to do a proper cal ride or upload a calride so we can have a look.
The wind sensor does not appear to be blocked. However, there are constant high winds in Southern Saskatchewan, therefore, it has almost been impossible to do a cal ride in calm wind conditions (during daylight hours). Attached are several calibration rides done over a period of two days. Please let me know what you think. Thanks.
Attachments
iBike_07_21_2013_1411_3_km_CalRide.ibr
(21.99 KiB) Downloaded 509 times
iBike_07_21_2013_1421_3_km_CalRide.ibr
(21.43 KiB) Downloaded 506 times
iBike_08_03_2013_1136_3_km_CalRide.ibr
(46.21 KiB) Downloaded 526 times
KenS
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Re: Average Watts Way Off

Post by KenS »

Stem mount for a TT bike doesn't sound like a good idea unless you have a RWS (Remote Wind Sensor)

And that last calride looks weird. Doesn't look like it was an out and back ride and you were riding at 10km/h?
-- Ken
BruceK
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Re: Average Watts Way Off

Post by BruceK »

KenS wrote:Stem mount for a TT bike doesn't sound like a good idea unless you have a RWS (Remote Wind Sensor)

And that last calride looks weird. Doesn't look like it was an out and back ride and you were riding at 10km/h?
The iPro on my TT bike has an apparent clear "view" of the wind without the bars, my forearms and/or hands obstructing. All of the rides were out and back. I have tried the RWS but the silly thing keeps popping out. As for the speed...I am not certain what was going on without referring back to my GPS data.

I am going to start from scratch by setting up a new profile and calibration ride. Hopefully, the wind conditions will be calm :)
Thanks.
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racerfern
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Re: Average Watts Way Off

Post by racerfern »

@BruceK

Don't use the cal ride at 1136. Something is clearly wrong with it.

The other two cal rides are OK to use and very similar in results. HOWEVER you played with the numbers and got yourself in trouble. The other day you uploaded a 40km ride and that profile has a wind scaling of 0.3xx instead of 1.3xx. No wonder you created a posting "Average Watts Way Off.

So the bottom line is make a profile with wind scaling about 1.375 and use all the other parameters. You should be just fine.

Yes, I would do a cal ride in near calm conditions. For me that means getting up before the sun comes up and the wind picks up. The calmer the conditions the easier it is for the unit and Isaac to pick up the slightest differences. If you get a wind scaling in the 1.x range then you probably do have a clear view for the wind port. However, on the bars you might find that some cross wind situations don't pickup the actual wind as well as you would prefer. It's usually not a big enough issue to be concerned about.

Do a calride to confirm a wind scaling in the 1.3-1.4 range, make a profile and ride. You should be fine. Needless to say, post up any files and we can drill down further.
Fernando
KenS
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Re: Average Watts Way Off

Post by KenS »

BruceK wrote:I have tried the RWS but the silly thing keeps popping out. As for the speed...I am not certain what was going on without referring back to my GPS data.
The GenIII RWS was a bit of an afterthought as far as I can tell and never really fitted properly. The Newton setup is way better
-- Ken
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Russ
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Re: Average Watts Way Off

Post by Russ »

On the RWS even on Gen III. ... I used a wide (about 1/4 inch) variety rubber band and give it one half twist after looping if over the neck of the wind sensor just above the plug. Then I pull the rubber band over the iBike and adjust its position to best help hold the RWS in place. Even now on the Newton, I had it pop out when I crossed some railroad tracks with a bit of speed so I went back to the rubber band always.

It also helps if you can form the tube and its mounting some how to put a bit of pressure into the iBike port.

Without the RWS, even with careful cal rides and careful hand placement I expect you may get added chaotic turbulence that changes a bit with wind yaw (direction) or even by a very small hand position change.

Regards,
Russ
BruceK
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Re: Average Watts Way Off

Post by BruceK »

Thank you Fernando, Ken and Russ for all your assistance and suggestions. It is nice to know that there are so many helpful people on this forum.

Cheers,

Bruce
BruceK
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Re: Average watts appear to be OK now.

Post by BruceK »

@ Fernando
New profile was established. Calibration ride + training ride is attached. Any/all comments and/or suggestions are welcome. I am hoping that this new data is more reflective of my actual power output on the road. Thanks. :D
Attachments
iBike_08_08_2013_1917_17_km.ibr
Training Ride
(176.99 KiB) Downloaded 537 times
iBike_08_08_2013_1909_3_km_CalRide.ibr
Cal Ride
(20.49 KiB) Downloaded 500 times
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racerfern
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Re: Average Watts Way Off

Post by racerfern »

Now you've got it! Nice job. Time for a fitness test.
Fernando
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