Jones' Stability Criterion

BikeCAD Pro calculates two values for the Jones' stability criterion. The value that has been calculated since the first version of BikeCAD circa 1998 is based on a formula from the book Bicycling Science 2nd Edition by Frank Rowland Whitt and David Gordon Wilson. In this formula, Jones' stability criterion is used to describe a bike's stability as a function of front wheel size, fork rake and head angle. Looking at these variables within normal ranges for a standard bicycle, one should observe that stability decreases with decreasing wheel size, increasing rake, and increasing head angle. It is recommended that Jones' stability criterion (u) lies between -1 and -3 (-1 is less stable than -3) In commercially available bikes, u tends to fall within a much narrower range than this.

In Bicycling Science 3rd Edition, the authors claim that they published the incorrect formula in the 2nd edition. Using the formula from the third edition, values tend to be positive numbers not numbers lying between -1 and -3. The third edition downplays the significance of the Jones' stability criterion. Jones' stability would have been taken out of BikeCAD all together. However, some users of BikeCAD Pro have requested that it be left in as they have already developed a sense of what Jones' stability values work for them.

The Jones' stability values are presented in the CSV output file (which can be imported into Microsoft Excel and other spreadsheet applications). To export a CSV file, choose File >> Export building specs (in CSV file).