Ibike watts show higher on bike

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mkpurt
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Ibike watts show higher on bike

Post by mkpurt »

Had a good ride today. I was pleased with my watts output until I download to my Issac software. My newton showed NP around 210 but after I downloaded it showed my NP around 170 watts. Why is there a difference between the two? During my workouts how do I know what actual wattage I'm putting out? Thanks for the help.

Mark
Velocomp
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Re: Ibike watts show higher on bike

Post by Velocomp »

Please post your ride file.
John Hamann
mkpurt
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Re: Ibike watts show higher on bike

Post by mkpurt »

John,
What's the best way to post my ride? I appreciate your help.
mkpurt
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Re: Ibike watts show higher on bike

Post by mkpurt »

here's the file.
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iBike_07_28_2013_1536_13_Miles.ibr
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Velocomp
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Re: Ibike watts show higher on bike

Post by Velocomp »

You have the "Automatically Analyze Route" feature turned on in Isaac. Isaac found what it thought was an out-and-back route, and adjusted your ride file accordingly.

I used the "Analyze/Return to Original Download" feature to return your ride file to its original form.

It looks like your Newton is properly calibrated, and that on the return part of your ride you took a different route, where there was a significant head wind.

Your Newton is right; 191W for the ride--good work!

Go to Edit/Edit Preferences/Analyze, and uncheck the box. That will stop the Auto Analyze feature from happening again.
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John Hamann
mkpurt
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Re: Ibike watts show higher on bike

Post by mkpurt »

Got it! Thanks so much for your help and quick response.
rstrom
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Re: Ibike watts show higher on bike

Post by rstrom »

Interesting ...

I went into the preferences in Isaac and saw that this setting was checked.

I don't remember checking it (who knows?). Is this a default setting?

After I saw this I looked in the documentation and saw this
TIP: IF YOU OWN A NEWTON OR GEN III UNIT, LEAVE “AUTO FINE TUNE”
UNCHECKED. YOU’LL SEE YOUR DATA DIRECTLY FROM YOUR IBIKE.
AUTO TUNING IS ALMOST NEVER NEEDED.
Looks like I should turn this off. Yes, No?

Will this change whether Isaac asks whether you finished in the same place that you started (e.g. set the altitude as the same if it ends up being different)?

Thanks,

Robert
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racerfern
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Re: Ibike watts show higher on bike

Post by racerfern »

Robert,

Unchecking the boxes (I have all of them unchecked) will not affect the choices presented to you when you select "Analyze Route". AFA "Analyze Route" I deselect all boxes (unless I have something go very wrong) and I don't use the "Ride Ended Where it started" even though it usually does. I ride with a significant amount of traffic which significantly affects overall wind speed.My average ride has a wind speed of about -1.5mph because of all the traffic. So clicking Ride Ended Where It Started raises the wind and skews the power numbers.

However, actually entering the beginning and elevation (even though they're usually the same) does not change what Newton (or a G3) saw for wind. The only adjustment is for a variation in barometric pressure or temperature changes. For example today's ride started and ended in the same place with a starting elevation of 28' and ending of -9' which is due to a combination of barometric change and temperature change. Setting both to 28' resulted in a change to the average power of .3 watts for the entire ride. IOW, analyzing the ride simply makes a pretty graph that doesn't have me ending submerged :oops: but other than that there are no changes.
Fernando
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Re: Ibike watts show higher on bike

Post by rstrom »

Fernando,

How do you set both to the same starting point? This is something I have not explored.

Thanks,

Robert
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racerfern
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Re: Ibike watts show higher on bike

Post by racerfern »

Robert,

Click Analyze > Analyze Route , I answer NO if presented with the question Did the rider draft? Even if I did, the Newton shows this with a significant tailwind. For example, here's today's ride with a very significant tailwind going up the canyon (the third lap). Isaac asks if I drafted but I don't care because I accept what Newton sas. Then the next question is did the ride end where it began? It doesn't matter what you answer, I usually answer YES. Now I make sure the three boxes on the left are unchecked (remember, "Ride Has Out & Back") will also affect the wind readings.

Now look at the right side radio button and click Enter Known Elevation. For the ride I've attached the starting is 25.6 and the ending is -8.9. I change them both to 28 which is what it really is. Now I get a pre-analysis of 117.8w and post ride analysis of 118.1w.

Try it.
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Fernando
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Re: Ibike watts show higher on bike

Post by rstrom »

Fernando,

Thanks very much for the detailed information!!

I definitely don't remember the enter known elevation working that way. If I am remembering correctly, the last time I tried to use that (a long, long time ago) I entered in a known elevation (an I could only enter in one) it did not behave very well and I had to revert the ride back to the previous results.

I will play around with this some.

Thanks again!!

Robert
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Re: Ibike watts show higher on bike

Post by rstrom »

Fernando,

Do you always say NO to the drafting question?

Here is a ride from last Saturday where I did definitely draft and there is a significant difference in wattage if I analyze and say no to drafting.

132w vs. 160w

Penny for your thoughts ;)

Thanks again ...

Robert
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rstrom
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Re: Ibike watts show higher on bike

Post by rstrom »

Whoa ... I just played with the "Analyze Route" a bit more and unchecked Drafting and unchecked Drafting and Ride Has Out & Back and then entered a Known Elevation with the start and the end the same and it went from the 160w back to the ~130w number.

That's cool and all but I am a little perplexed.

If the ride has that it ended where it began then shouldn't the same elevation already be assumed?

Robert
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racerfern
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Re: Ibike watts show higher on bike

Post by racerfern »

Correct, I always answer NO to the drafting question. There are combinations of check boxes and radio buttons that change things significantly and others that only make a minor change based on elevation differences. So...

I opened your ride and clicked return to original download. Clicking Ride ended where it began changes the avg watts significantly because it changes the average wind speed from 14.9 to 19.2! That's why your watts jump so much. However clicking the Drafting checkbox cancels that out and brings you back to 132. You can confirm this by checking the drafting box and watch the watts drop then uncheck and it jumps back up.

Entering the know elevation cancels out the possibility of drafting being an issue but the out/back check box can still raise havoc IMO. Even if only part of the ride is called an out/back (like yours) it affects the wind for the entire ride. This is why I always uncheck drafting, wind changed and ride has out/back, then I enter the starting and ending elevations. I just let the Newton speak for itself and I'm very satisfied with the results.

The problem as I see it when a ride started and ended at the same place is that the wind changes dramatically, when actually entering the elevation even if it's the same the wind is taken as was recorded.
Fernando
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racerfern
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Re: Ibike watts show higher on bike

Post by racerfern »

For the ride you posted, obviously a group ride were you tucked in the pack for the first third and the last third? It appears so, I just want to confirm your profile is good.

Never mind, it seems you've been using this for quite awhile so I'm sure you've got it dialed in.
Fernando
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Re: Ibike watts show higher on bike

Post by nsidirop »

Now I am perplexed and a little worried.
First I have never unchecked the Auto analysis box, I simply assumed that it was default setting since it has always been checked and I haven't bother to change it. What exactly happens when I uncheck it? Is it the same as unchecking the Ride has out and back under route?

If I put in numbers by using Enter Known Elevation, then ok and then click on Ride Ended Where it Began, for a short moment a window comes up saying Examining Wheel Acceleration. What is this and why do my entered elevation numbers change if I click back to Enter Known Elevation?

If I am doing a group ride with obviuos drafting effect should I still uncheck the Drafting In This Ride, even if Isaac automatically checked it because it detected that I was drafting?

Finally here is a ride I did yesterday, first part with a group, then we rode in pairs and finally I was alone on my way home. What settings / boxes should I use / check ?
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racerfern
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Re: Ibike watts show higher on bike

Post by racerfern »

All those checkboxes and options are there to help analyze a ride that had a problem with recording the correct wattage. They're awesome when used as needed but can make things confusing.

If you click ride ended where it started then click starting and ending elevation then go back to ride ended where it started then go back to enter starting and ending elevation you will have to reenter the numbers since clicking the upper button wipes out your input. That's the way it is.

That's why I used enter starting and ending elevation, it tends to keep the numbers truer to what was experienced and even checking Drafting won't skew the numbers.

I haven't looked at the ride file which I will do this evening but I've had a lot of rides similar to yours and I assure you the Newton does a great job of figuring things out while on the ride.

EDIT: I just looked at the ride file and using the known elevation yields 199w and also checking raises it less than one watt. I think you're fine. I do recommend that you set your elevation correctly so that there's no second guessing. That is unless you really did start at -20m which is possible in a few places in the world.
Fernando
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Re: Ibike watts show higher on bike

Post by nsidirop »

Thanks Fernando, your input is always helpful. I always put in the elevation numbers after the ride in Isaac.
In this case it should be start elevation 14 m and end elevation 149 m. That gives me 214 W average. Since it was partly a group ride I left the box Draft in this Ride checked.
If I don't change the elevation (elevations -24 min, +110 max ), the original download (under Analyse Route) says 213 W.

The 199 W I don't recognise, how did you get that?
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Re: Ibike watts show higher on bike

Post by racerfern »

Not knowing the elevation and assuming it started and ended in the same place I put in the the SAME starting and ending numbers. But of course you knowing the elevation you have to use those.
Fernando
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Re: Ibike watts show higher on bike

Post by nsidirop »

Ah, got it. Thanks
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