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High watt readings while coasting

Posted: Sat May 07, 2011 9:40 pm
by Bike4Him
I have an iSport and have done many, many cal rides and coast downs, and e-mails to the iBike guys.
I've settled on a cal ride that seems to be good enough in the est fric and est aero numbers.
I believe I have things figured out pretty well. After 800+ miles I think it's consistent and hopefully accurate.
I am leary of the fact that many times the solution to issues discussed here seem to be tweaking settings via download.
With the iSport you cannot do the tweaks, but in my opinion, changing the info manually to get accurate results doesn't make sense.

All that being said I get readings while coasting downhill of 100+ many times. If I tap the brakes I can get it to zero but it will go back up.
On a 8%+ grade I can get readings of 300+ easy.

Tilt is correct
I zero the wind at the start and if the temp goes up.
I've got good cal ride and accurate info entered in set up.

Any thoughts.

Re: High watt readings while coasting

Posted: Sun May 08, 2011 8:49 pm
by Morocco Mole
could you upload your profile, it's sounds like your CDA value is incorrect.

Re: High watt readings while coasting

Posted: Tue May 10, 2011 12:19 am
by Bike4Him
Morocco Mole wrote:could you upload your profile, it's sounds like your CDA value is incorrect.
It's an iSport. you cannot upload profiles or rides.
This is the part where I lose confidence because we would need to tweak input to get correct output.

Someone here said the iBike is a power estimator. It's more like a gateway PM.

Any other thoughts. I've got many rides coming up that involve long steep descents.

Re: High watt readings while coasting

Posted: Tue May 10, 2011 9:55 am
by Velocomp
Any measurement device is only as good as its calibrations, and it is a fact that the iPro and iAero devices can be calibrated more precisely than the iSport, both because of the iBike software and because of the ability to perform multiple coast downs.

Coast downs are particularly tricky for the iSport, because you get only one coast down. With the Pro or Aero, you can do as many coast downs as you wish, then use the iBike software to analyze and improve.

I suggest you go into Racr sequence and reset Crr to 55. Then, do the Fast Start sequence, followed by a calibration ride. This will provide the best setup for your iSport.

If you want to try for more precise calibrations you should upgrade to the iPro.

Re: High watt readings while coasting

Posted: Tue May 10, 2011 10:13 pm
by Bike4Him
Velocomp wrote:I suggest you go into Racr sequence and reset Crr to 55. Then, do the Fast Start sequence, followed by a calibration ride. This will provide the best setup for your iSport.

If you want to try for more precise calibrations you should upgrade to the iPro.
I have started to consider the cost / benefit.

The FriC screen shows 55. is that Crr
I believe I have a good calibration ride that followed a fast start sequence.

Re: High watt readings while coasting

Posted: Tue May 10, 2011 10:21 pm
by Bike4Him
slightly off topic.
What is the total cost to upgrade and have all software necessary?
I like the iSport. I am hooked on training by power. I have a low budget.
Thanks

Re: High watt readings while coasting

Posted: Wed May 11, 2011 6:41 am
by Velocomp
Here is where to get details:

http://www.ibikesports.com/detail.aspx?ID=66

Re: High watt readings while coasting

Posted: Thu May 12, 2011 12:46 am
by Bike4Him
Bike4Him wrote:
Velocomp wrote: The FriC screen shows 55. is that Crr
I believe I have a good calibration ride that followed a fast start sequence.