Fitter - Bike 4+

The safe way to ride bike

Jongheon Lee

    • 4.6 • 28 Ratings
    • Free
    • Offers In-App Purchases

iPhone Screenshots


The effective and safe way to ride bike.
Easy to measure and fix your posture to prevent injury.
Take a picture of your cycling posture.
See the proper cycling posture diagnosis.

What’s New

Version 1.1.8

Fix crash

Ratings and Reviews

4.6 out of 5
28 Ratings

28 Ratings

alireza9900 ,

Watching Ad to see analysis causes crash

UPDATED REVIEW: Upon discussing the crash problem with the developer, he fixed the problem very soon. And upon further discussion about the aligning guide of the app he helped me to understand the correct setup and said that hopefully he will fix that in the near future as well. Now it’s highly recommended.


ORIGINAL REVIEW: Seems like a decent app, only problem is that when trying to see the detailed analysis by watching an advertisement, the app crashes. Also another thing that is confusing is alignment of the camera. When set at 2.5m from the bike and camera at handlebars’ height, like the instructions suggest, the bike frame guide won’t align with the bike and the camera has to be lowered and set farther away, for the guide to line up with the bike frame. Device used is iPhone SE 2nd generation running on iOS 15.6.1.

Developer Response ,

i resolved the crash problem and will fix the guide asap
Thank you for feedback

Jack Steve 😝 ,


This app is the most helpful app I have ever used when it comes to bicycle fitting. I ran to my neighborhood uphill and could feel the difference right away.

This app uses machine learning feature of iOS and shows all major angles of your body when your crank is 12:00, 3:00 and 6:00 position. Funny thing is that I thought my saddle height was a bit low but app showed it was actually too high. Same thing with my stem length. I thought it was a tad long and it turned out to be a bit short.

Just to know the idea in my head were all wrong made me feel grateful and purchase the “pro” version which removes ads.

GSD1975 ,

It’s OK

The app seems to struggle finding when the crank is level for the saddle for and aft. I believe this is due to needing great lighting. Also at regular cadence or higher the ball of foot is hard to determine due to blur. We added a piece of tape to shoe to help. The Ad watching is annoying as well. Well actually there isn’t an ad so it’s just a blank screen while you wait.

Basically it could be great with some minor tweaks.

App Privacy

The developer, Jongheon Lee, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Purchases
  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Some in‑app purchases, including subscriptions, may be shareable with your family group when Family Sharing is enabled.

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