GPX merge

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Brodirt
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Joined: Fri Jan 11, 2008 2:17 pm

GPX merge

Post by Brodirt »

I am having an issue with GPX merge into my ride files.
Strava does not seem to do power very well when you consider the post ride analysis adjustments Isaac does, so I always try to upload my corrected files.
When I upload to Strava I almost always get large sections of the ride that are recorded as long straight lines, as though I rode as the crow flies rather than on the road.
The mileage and elevation are therefore off as well.
Example, yesterday's real ride was 42 miles, 2600' feet of elevation and about 2:20. The Newton recorded it well and it matched the Strava iPhone recording closely except for elevation which Newton does much better.
The uploaded ride is 55 miles, over 3 hours and only 1500' or so feet of elevation.
Strava tech support says its not their error and given that you can see the error on the Isaac merge graph and map I agree.
Any help would be appreciated.
Velocomp
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Re: GPX merge

Post by Velocomp »

please post a ride file showing the problem
John Hamann
Brodirt
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Re: GPX merge

Post by Brodirt »

Do you want the ride file from Isaac or a link to the Strava file?
Velocomp
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Re: GPX merge

Post by Velocomp »

both, if it's possible to provide them
John Hamann
Brodirt
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Re: GPX merge

Post by Brodirt »

Link to Strava
http://app.strava.com/activities/168630988

Newton ride file with GPX merged is attached
Attachments
07_20_2014_1221.csv
(1015.47 KiB) Downloaded 286 times
Velocomp
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Re: GPX merge

Post by Velocomp »

Please post the original Isaac .ibr file, not the csv file, with GPS data merged.

What device/app are you using to get your GPS data?
John Hamann
Brodirt
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Re: GPX merge

Post by Brodirt »

GPS data is through iPhone and Strava app.
I have a Wahoo fitness ant+ dongle which is connecting to the Newton in ride.
I have my doubts about Strava's data, as I said originally, but Im more concerned with getting the GPS track right.
File is annexed.
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07_20_2014_1221.ibr
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Velocomp
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Re: GPX merge

Post by Velocomp »

Sadly, it's impossible to figure out what is going on.

If I understand things properly you are running the Strava app on your iPhone, and picking up your Newton data through an ANT+ dongle that is connected to your iPhone. The Strava app is merging the Newton data with its GPS data.

I don't understand how you are getting the GPS data into Isaac, unless you are doing a post-ride merge of their ride file into Isaac.

If the above is correct you are using an app that we can't vouch for, with a dongle we have not used either.

Frankly, I don't know how Strava can say the error is not theirs, because the data is being gathered from their app.

Clearly, the GPS data is wrong. Either the GPS signal is poor or the app is not right.

We have not seen this issue elsewhere.

My suggestion is that you use the Newton Tracker app. Isaac will seamlessly merge the NT data for GPS with your Newton data (no dongle required) and then you can load the file from Isaac into Strava.
John Hamann
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Re: GPX merge

Post by Brodirt »

All I am doing is merging correct GPS data into my file via Issac.
I know the data is correct because I upload the original file first to check that the GPS track is right.
The GPS coverage is also confirmed by Strava via complete GPS tracks from multiple others on group rides.

The issue of the wahoo fitness dongle etc is a non-issue.
I am downloading a good GPS track from Strava, merging it into a good Newton file in Isaac and coming out with an error in Isaac.
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racerfern
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Re: GPX merge

Post by racerfern »

Since you are using the Strava app, where did you get the gpx file from? The strava web page? Please upload the GPX file as I don't see where the link is to download the ride. Perhaps only you as the user can download the file.

And I agree with Velocomp, the Newton tracker is fantastic with no drops. It merges perfectly into Isaac and the entire thing exports as csv and uploads to Strava without a hitch.

Hey now that I live on the right coast maybe we'll get out and ride soon.

http://app.strava.com/athletes/4872825, note that I deleted all my west coast data and I am now a newbie again as far as Strava is concerned.
Fernando
KenS
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Re: GPX merge

Post by KenS »

I wonder if this is related to a problem I sometimes encounter -but never as bad as this. Sometimes when Isaac matches up the GPS file to the iBike file it has points that go backwards in time. This seems to happens around stops.
A hint as to a possible cause is in the graph that is displayed during the matching process. The iBike data is displayed based on Ride Time whereas the GPS data is displayed using Actual Time. You can see in the screen shot that the graphs get progressively further apart at each stop.
I suspect that when Isaac does a resynch after detecting a stop it sometimes gets it wrong.
TCX merge with iBike
TCX merge with iBike
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-- Ken
jazclrint
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Re: GPX merge

Post by jazclrint »

Again, here I go with another old thread, but I ran into a similar thing with the sample file in Isaac I played with today. For grins and chuckles try MapMyRide. I think it is that very thing. When you stop Isaac knows (or only looks at ride time), but Strava includes actual time. In MMR it will break things down into equal chunks and you will see the chunk you took a break in has a really low ave speed, like 3.5mph or something. And on the graphs it looks like a straight line from the last measurement taken before the break to when the Newton started recording again. But MMR is smart enough to know not to count it in the overall results. Strava doesn't seem to be that smart. What I found today is that MMR read a low cadence ave, and did not use the Newton's alt data, but got everything else right. Strava got the alt data and the cadence right, and everything else wrong. I have put a suggestion into MMR that they be iBike friendly and support .csv files, and use the iBike's altitude data. They aren't the quickest at keeping up with the programming, but on the site they insist they try to be friendly to all products. So we'll see what happens
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