PowerPod position and the rain

PowerPod position and the rain

Postby spangelsaregreat » Wed Sep 13, 2017 2:06 pm

Hi,

I had my first ride in very heavy rain today and you will see from the attached ibr file the PowerPod did not deal with it well.

I am aware from previous posts that in very heavy rain that water gets into the wind port and it messes up the Power reading. I know John's advice is to let it dry out and it should be fine.

I was wondering if the position of the PowerPod on the bike affects this?

I have mine mounted on an out front mount at present so I guess it is more exposed to the wind and rain etc. Would using the supplied mount on the bars perhaps offer a slightly more sheltered position and make it less affected by the rain? I live in Scotland so rain is fairly regular.

I have it pretty well dialled on the out front mount just now, do I need to make any changes to the existing profile if I move it to the bar mount? Hoping I won't need to do a new calibration ride.

Regards
Attachments
iBike_09_13_2017_1630_13_Miles_HiDef.ibr
(418.88 KiB) Downloaded 10 times
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Re: PowerPod position and the rain

Postby Velocomp » Wed Sep 13, 2017 2:13 pm

Putting PP on a front mount is the worst-case position if you ride a lot in the rain. Your front tire is like a fire hose, spraying water constantly at PP.

A handlebar position might be better. If you move it you will need to do a new cal ride.

By the way: I used the Analyze/Repair/Repair blocked wind sensor" feature to remove the wind sensor issue. Attached; you did some nice hill repeats!
Attachments
spangelsJRH_09_13_2017_1630_13_Miles_HiDef.ibr
(421.32 KiB) Downloaded 11 times
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Re: PowerPod position and the rain

Postby spangelsaregreat » Wed Sep 13, 2017 4:03 pm

John,

Not sure you are able to use the words "nice" and "hill repeats" in the same sentence!

I have moved it to the supplied mount on the bars.

Regards
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Re: PowerPod position and the rain

Postby Velocomp » Wed Sep 13, 2017 5:32 pm

spangelsaregreat wrote:John,

Not sure you are able to use the words "nice" and "hill repeats" in the same sentence!

Regards


:-)
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Re: PowerPod position and the rain

Postby spangelsaregreat » Thu Sep 14, 2017 12:46 pm

John,

I did the new calibration ride today on the way to work and it all went fine. I have attached the Cal Ride IBR.

When I rode home today the watts seem high compared with what they were before. I did an FTP test and my FTP is 318. On ride home the watts seem to easily go past my threshold and run about 100 watts over what I would expect. I did a hill effort and had an average power of 385w. My threshold is 333 so this seems a bit high.

On comparing the profiles the figures are more or less the same between my previous out front mount position and the new bar position. Looking at the Advanced Tab the figures are

Out Front mount
Aero 0.579
Wind Scaling 1.610
Cda 0.360
Fric 11.604
Tilt -0.7
CRR 0.0048

Bar mount
Aero 0.695
Wind Scaling 1.913
Cda 0.363
Fric 11.847
Tilt -0.7
CRR 0.0048

So the main differences seem to be Aero and Windscaling. I noticed when I first set up PowerPod it was reading high watts and on doing a new Cal ride it got better. I am sure the Wind Scaling was about 1.9 when it was reading high watts.

Can you advise if changing the Wind Scaling or Aero would get the watts to read lower and more realistic? When I did an FTP test on the old setting it gave me 372 as my FTP which does seem high. 318 would be more realistic for my current lack of fitness! Don't want to have to do another FTP test based on this new cal ride if I can help it!

Cal Ride
iBike_09_14_2017_0813_4_Miles_CalRide.ibr
(111.43 KiB) Downloaded 6 times


Ride home from work
iBike_09_14_2017_1613_13_Miles_HiDef.ibr
(450.4 KiB) Downloaded 9 times


Regards
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Re: PowerPod position and the rain

Postby spangelsaregreat » Fri Sep 15, 2017 3:25 pm

Hi John, have you had a chance to look at this?
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Re: PowerPod position and the rain

Postby Velocomp » Fri Sep 15, 2017 4:04 pm

Unless your ride was in a constant headwind, I think your wind scaling is a bit "hot".

Corrected profile is attached.
Attachments
spangels.ibp
(429 Bytes) Downloaded 9 times
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Re: PowerPod position and the rain

Postby spangelsaregreat » Fri Sep 15, 2017 6:36 pm

John,

Thanks I will give that one a try. The first eight miles was a headwind but about 4 miles of that was on a very sheltered canal path. After 8 miles it was a bit of cross wind and tail wind.

Out of interest how do the various calibration values affect power readings?

Rider Weight:- How much weight change would require a new value being applied?
Aero:- Is this how aero a rider is? e.g on the drops etc
WInd Scaling:- what is this exactly?
Fric:- what is this exactly?
CRR:- I am using tubeless tyres so from a previous post of yours I select tubular as the option. Is that correct?

Regards

Keith
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