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Cog Display


This app calculates the gear ratio that you are currently using based on your cadence and your speed. Since it is impossible to determine what chain ring you are using, the app will display all the estimated cogs. For instance if you have a double chain ring 34/50, it will display the estimated cog for the 34 chain ring on the left and the estimated cog for the 50 chain ring on the right. It wo...

What’s New

Bug fix (1.0.4): On Edge 520, the display was very small. I believe it is now fixed with this version, but it is hard for me to test it since this bug does not appear in the Garmin simulator.</p><p>(1.1.0): Added support for Fenix 3 watch

Additional Information

  • Edge® 1000 Edge® 1000
  • Edge® 520 Edge® 520
  • Edge® 520 Plus Edge® 520 Plus
  • Edge® 820 Edge® 820
  • Edge® Explore 1000 Edge® Explore 1000
  • Edge® Explore 820 Edge® Explore 820
  • fēnix® 3 fēnix® 3
  • fēnix® 3 HR fēnix® 3 HR
Average Rating: (28 Ratings)

13 April 2018 | Version 1.1.0

Great app, keep up the great work!!

Hybrid Noob
13 March 2018 | Version 1.1.0

Stumbled upon this and gave it a try on the trainer at first - all good and impressive but surely it can't cope with the gradient changes outside? How wrong I was! I'm incredibly impressed with the accuracy, having just returned from a ride over very varied terrain. Within a second or two the display was consistently showing the correct cog, whether I was powering along the flat or out of the saddle while climbing a steep 15% incline. It now has me wondering quite how it calculates the ratio so accurately, in spite of all the gradient changes, using only cadence and wheel speed??? :/ The one exception is, understandably, when you are spinning out going down a downhill. Of course that's a total non issue given the second you are putting out any meaningful power the display corrects almost instantly. All in all a wonderful little app. For someone who occasionally loses track of the gears and glances down at their cassette this is a nice quality of life addition - if gear display is good enough for Di2 this app is good enough for everyone else!

Developer Reply
16 March 2018, Clement_Barthes

Hey Hybrid Noob, thanks for the kudos! To answer your question, it calculates the ratio using error minimization. Instead of coding IF LESS THAN but MORE THAN etc... you can compute the error between the measured ratio and the ideal ratio of each cog/chainring pair. Once you've computed all the errors, you rank them and display the lowest one...Tada!!! This approach always give great results . You can check out my code if you click on the source code link, it's very simple if you code a little bit.

Álvaro Carreras Espallardo
14 October 2017 | Version 1.1.0

Una aplicación indispensable, me encanta ya que no tengo que mirar atrás para ver en qué corona voy. Gracias a esta aplicación me he aprendido de memoria los piñones que tengo.

Paumier Jean-Michel
06 October 2017 | Version 1.1.0

Presque parfaite... manque juste deux petites choses : le 12ème pignon et pouvoir visualiser le graphique dans Garmin connect. Merci

03 October 2017 | Version 1.1.0

Fantastic. It works perfectly. Simply and clear. Thank you so much.

Peter Schneiderhan
04 September 2017 | Version 1.1.0

I miss the Setting for my 1x12 Speed Chainrings

Nico G
08 August 2017 | Version 1.1.0

Super application ! Fonctionne vraiment bien et rapidement. Un plus serai de pouvoir avoir l'historique des valeurs / log dans l'activité Garmin Connect Merci !

02 August 2017 | Version 1.1.0

Bravo et le fait de proposer le code source c'est un super exemple. Reste plus qu'à connecter ça avec un Di et on a une boite auto :)

25 July 2017 | Version 1.1.0

de la balle , hyper réactif , que du bonheur plus besoin de regarder la roue arrière.....

Alberto Vitali
20 July 2017 | Version 1.1.0

It works very well. I use it on MTB with Eagle 12V, It's possible to add the 12th cog? Thanks!

Antonio Lopes
14 July 2017 | Version 1.1.0


30 June 2017 | Version 1.1.0

Very good. I would prefer to see only the active rear cog number (1-10), and much bigger. Once on the trail it is hard to read the small numbers. Good work, thanks!

Θανασης Τολιας
27 May 2017 | Version 1.0.4

nice but don't work....

Developer Reply
28 May 2017, Clement_Barthes

Well it does work for everyone else so there must be a solution to your problem. What's wrong with it?

15 April 2017 | Version 1.0.4

J'étais un peu septique au début au téléchargement et puis après 3 secondes d'utilisation bluffé marche..... génial quand on voit que pour avoir un capteur certe avec plus d'info mais chez shimano pour le DI2 c'est 80€ génial

01 April 2017 | Version 1.0.4

Increíble! Aunque me gustaría recomendar una mejora estética en el sentido de que el título de la cuadrícula y el dato ofrecido deberían estar separados, así como aumentar el grueso de la fuente.

Olivier Janssens
26 March 2017 | Version 1.0.4

Bluffant ! Apporte vraiment une information supplémentaire et intéressante sur le Edge. On passe une vitesse et en moins de 2 secondes le nouveau braquet est affiché à l'écran. Fini de devoir baisser la tête pour regarder sa cassette. Je recommande vivement. Bravo et merci au concepteur pour ce partage.

12 March 2017 | Version 1.0.4

The app work well, I have the only problem that I can succeed to save my chainring and cog. I modify them but every time I connect garmin 520 i found the stock entries.

Developer Reply
15 March 2017, Clement_Barthes

Hi Nico, Sorry about this, that's an issue to address to Garmin actually. I suggest that you use always the same device when you sync your Garmin. For instance, if you use only your phone, you can change the settings on your phone in the Garmin app. If each computer and each phone that you use has the correct settings then it should fix the problem.

Mark Richards
04 March 2017 | Version 1.0.4

The app worked very well on my Edge 520 (running v10). The label and numbers didn't quite have the same spacing in a five-row page as the built-in data fields but it was close enough. The update to v11 appeared a few days ago and after loading that, something broke with this data field. I deleted and reinstalled it and the issue persists. The small ring field shows only 000 while the large ring field is displaying a number with a decimal place.

Developer Reply
06 March 2017, Clement_Barthes

Hi, Sorry about this, I suspect your settings got screwed up. Can you try to reset your gear teeth etc?

26 February 2017 | Version 1.0.4

Genius! Accurate and responds very quickly to gear change.

26 February 2017 | Version 1.0.4

All is OK with my edge 1000, 50X34 11 v 11-28 La première appli du genre qui fonctionne !! Thank you

Steeve Isoz
25 February 2017 | Version 1.0.4

Très sceptique lors de l'installation, j'ai été bluffé lorsque j'ai testé cette application lors de ma sortie du jour. Lors du changement de pignon, 2 secondes suffisent pour que mon Garmin affiche le bon rapport. De plus, chaque fois que j'ai contrôlé le le pignon par rapport à ce qu'affichait mon Garmin, c'était juste! Bravo à son développeur et surtout merci!

Charley Donovan
24 February 2017 | Version 1.0.4

Works great on my Edge 1000. Didn't need to count the teeth on each cog of my Dura Ace cassette. Shimano publishes that information: Simply click on your cassette and then on "Detailed Product Page" where it lists each "Sprocket Size." Shimano shows detailed cog information for Dura Ace and 105 but, oddly enough, not Ultegra. Possibly the cogs for Ultegra are the same as for Dura Ace (although there's no Dura Ace 11-32)?

21 February 2017 | Version 1.0.4

So far I have not found any problems with the Edge 1000, works perfectly and is very visible in any size of field.

Huw Jones
17 February 2017 | Version 1.0.3

Genius! Accurate and responds very quickly to gear change.

15 February 2017 | Version 1.0.3

Very interesting this app, I'm using the Edge 1000, with cadence and velocity sensors and with a speed setting: two 24/34 chain rings and a cassette 11 speeds 10/42. I noticed that the indication for the current ring used is very constant, and the indication of the unused one is constantly changing, so it would not be possible to indicate the chain ring actually used? Another suggestion would be the option to indicate by continuous numbering (1,2,3 ...) the cog used, with 1 for the larger gear of the cassette. Congrats on the job!

Developer Reply
16 February 2017, Clement_Barthes

Hi Mazinhobender. You are correct, in many configurations the correlation is very accurate for one chain ring and not for the other, so it would be possible to guess. But at times, especially in mid-range, the correlations are too close to be guessed. I do not know how to translate that on the interface, maybe gray out the value when the correlation is poor? Your second suggestion would be much easier to implement, I could let people choose in the config. menu. But first I'd like to fix this small display bug that occurs on the edge 520. Any problem with that on your edge 1000?

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