Author Topic: .fit file analysis  (Read 756 times)

quixoticgeek

  • Mostly Harmless
.fit file analysis
« on: August 25, 2019, 11:39:20 am »

Now I have di2, and it is synced with my wahoo, I believe that my every gear change is now logged in the .fit file.

Are there any tools (preferably linux or online), that would allow me to look at the gear shifting data in the .fit files?

Thanks

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

fuaran

  • rothair gasta
Re: .fit file analysis
« Reply #1 on: August 25, 2019, 02:31:05 pm »
Try Golden Cheetah?
It can do loads of analysis. Think it has some support for Di2 data. Runs on Linux or Windows etc.
http://www.goldencheetah.org/

quixoticgeek

  • Mostly Harmless
Re: .fit file analysis
« Reply #2 on: August 25, 2019, 04:11:23 pm »

Perfect, that did the trick! Interestingly it logs it as the gain ratio. Rather than derailleur position, hadn't expected that.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: .fit file analysis
« Reply #3 on: August 26, 2019, 08:53:09 am »
I wonder if it is using the di2 at all. It could work out the gain ratio by comparing cadence to wheel rotation.


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Re: .fit file analysis
« Reply #4 on: August 26, 2019, 09:01:12 am »
Out of interest, what are you hoping to find from the data?

If if were me, I think I’d be interested in whether my perception of gear use matches reality. I suspect I’m much more aware of the gear I’m on when the going is hard. Also, how cadence relates to effort and whether I’d be better off changing gears differently (that probably needs hrm too). But, I lack the funds so that’s very hypothetical :)

Re: .fit file analysis
« Reply #5 on: August 26, 2019, 09:17:23 am »
Di2 doesn’t know or care what chainwheel/cassette you have* so davef’s theory seems more likely.

(* except when setting up synchro)

quixoticgeek

  • Mostly Harmless
Re: .fit file analysis
« Reply #6 on: August 26, 2019, 09:21:37 am »
Di2 doesn’t know or care what chainwheel/cassette you have* so davef’s theory seems more likely.

(* except when setting up synchro)

I'm running synchro...

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: .fit file analysis
« Reply #7 on: August 26, 2019, 09:36:34 am »
Yes, but if you were designing a system to log/display Di2 gear data, you’d need it support everyone not running synchro too.

I mean the only way to find out is to test it - e.g. log a ride without your cadence sensor and see if it still shows ratios. But my money is on it not using the Di2 data.

Re: .fit file analysis
« Reply #8 on: August 26, 2019, 10:23:23 am »
Yes, but if you were designing a system to log/display Di2 gear data, you’d need it support everyone not running synchro too.

I mean the only way to find out is to test it - e.g. log a ride without your cadence sensor and see if it still shows ratios. But my money is on it not using the Di2 data.

Turns out Golden cheetah uses di2 data if present, otherwise calculates from speed and cadence.


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Kim

  • Timelord
Re: .fit file analysis
« Reply #9 on: August 26, 2019, 11:11:48 am »
It's presumably assuming the crank length, too.  Speed and cadence only allows you to calculate development.
Careful, Kim. Your sarcasm's showing...

Re: .fit file analysis
« Reply #10 on: August 26, 2019, 11:27:29 am »
It's presumably assuming the crank length, too.  Speed and cadence only allows you to calculate development.
No. It is only displaying the ratio of front chain ring to rear cog so 52/13 is shown as 4.00. This also means wheel is rotating 4.00 times for each crank revolution. Wheel rotation rate can be picked up from wheel sensor or calculated from speed and circumference. Although crank length affects overall gear ratio, this is not shown in this metric.


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Kim

  • Timelord
Re: .fit file analysis
« Reply #11 on: August 26, 2019, 11:30:38 am »
It's presumably assuming the crank length, too.  Speed and cadence only allows you to calculate development.
No. It is only displaying the ratio of front chain ring to rear cog so 52/13 is shown as 4.00. This also means wheel is rotating 4.00 times for each crank revolution. Wheel rotation rate can be picked up from wheel sensor or calculated from speed and circumference. Although crank length affects overall gear ratio, this is not shown in this metric.

Ah, so it isn't showing gain ratios in the conventional sense (distance travelled by pedal to distance travelled by tyre), but the gear ratio.  That makes even more sense.
Careful, Kim. Your sarcasm's showing...