The unusual sensor around which this project is based is the stainless steel "Digital Indicator with Data Output Port" sold by B.G. Micro. I learnt a lot about how to hack this obscure tool in David Cook's Robot Room (http://www.robotroom.com/Digital-Indicator-3.html).
Because this linear measurement tool is based on a digital caliper, it has the same “24-bit” format as the data protocol for many other oriental calipers. You can read all about that subject here: http://www.robotroom.com/Caliper-Digital-Data-Port-2.html.
Much of the code in this projects Arduino sketch is about filtering the strange spikes in the generally noisy signal from the indicator.
As the application here is a hand-held tool to directly measure the tension of bicycle spokes, you obviously have to calibrate it first against some reference spokes under controlled tension. The methodology for such a calibration is another story.
Anyway, this is what the finished tensiometer looks like.
The values are presented on a standard I2C driven 1602 LCD (not shown above) in this manner:
Link to the project description: http://xneb.org/mabe/xnebmisc/home/tensiometer.html or https://sites.google.com/view/xneb-project-logs/home/tensiometer