Mad props for a great app! ...some thoughts and possible feature ideas.

First, just wanted to give a big thank you to the developer of this app! It has amazing features and flexibility for us data geeks, so thank you for such a great product at an amazing price. While it seems that your app may be a bit more focused on Road Courses, I use this App exclusively for Autocross. With that in mind, I would like to share some thoughts about how this app could be even more focused on Autocross and its possible that these thoughts would transfer to road courses as well.

Years ago, I used a product called "Extreme Geez" that was autocross focused tool and worked with an external G-sensor and a Palm Pilot PDA. While not nearly as powerful as Racechrono, l it did have a few very useful features / data points that I have yet to see on current Lap Timer and Driving Analysis offerings. IMHO it was way ahead of its time when used for driver and chassis development.

Here is a write up I did on the product in 2002, nearly 20 years ago !! (I have zero affiliation with the product)

I shared how I used this to see how well we were driving on a given day and what was happening with the car and how we could tell what was us and what was the car.

A quote from that post I made about the "Usage" rating which was used as a metric to determine how well you were using the capabilities and the grip of the car looking at lateral and longitudinal grip available on any given day.

"The colors on the map represent your usage rating.

The car is capable of X amount of grip in any direction at one time. Geez knows what this is based on your sustained G's readings in all directions. This is also known as your friction circle. The idea is to ride the edge of the friction circle as you go around the track.

The USAGE rating depicted in the colors represented on the maps tell you how close you are to the edge of the friction circle at any given point on the track.

Light blue means your over 90% usage
Dark Blue over 80%
Pink over 70%
Red below 70%

So the more light blue you see the better. The more red the worst..."

(sorry the pictures are long gone from this post)

Im not clear on how this worked, but the rating was consistent with how our times benchmarked to other cars and drivers we raced with time and again. The higher the rating, generally showed in our times.

Im guessing sustained G loads were a short samplings such as a handful of the highest G loads.(.5-1 sec??) that would give you an idea how well the car was actually gripping in each direction on that surface that day with the given setup.. It was long enough to provide useful data on the cars grip but not long enough for a drivers inputs to affect it much. Peak seems a bit useless as it could be caused by a bump or other anomaly. I believe this was what the "Usage" rating was derived from.

Other useful data points were "Aggressiveness" "Smoothness" which would give one an idea how quickly and smoothly they are making the transitions between wheel input, throttle and brake.

For example, I have found using your tool to determine what I feel is the aggressiveness of my runs vs my wife's by manually going through the data accounts for roughly 1.5 seconds difference in time on a 60 second course. She is equal to my times or faster through sustained corners. Figuring this out is fairly time consuming, where some general formula based ratings or data points can quickly help determine what is going on with your driving style between runs.

While long, hopefully you find some of this information a bit useful. Regardless, thank you for your time.



  • edited June 2021
    Thank you for the feature idea. The future of RaceChrono will bring features based on the accelerometer and a friction circle is probably one of the more obvious ones to do. Not sure if I will have the agressiveness scale at first, but at least the circle if a straightforward thing to do.
  • It would also be great to make the color coding better when using "Combined acceleration" as a "Driving line color channel". I just reviewed one of my laps: based on graphs I didn't trail brake in a few corners, but I can't see that on the map, since the driving line is just solid green in those areas.

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