The four common flex types are bending, rolling, torsional and variable. Considering the flex type for an application is important in determining how each component within the cable is manufactured. When designing for extended flex life, the general rule of thumb is to apply a 10:1 diameter-to-bend ratio, where the diameter of the cable is less than or equal to 10 times the radius of the bend. It should be noted that this may require designs capable of withstanding a severe applied torsion. Variable flex is depicted below.

Figure 1	Bending Flex: Cables should be configured with the tightest lay length possible and the conductors should be neutralized in bending flex applications.
Figure 2	Rolling Flex: Linear slide apparatus and cable track systems call for cables that can withstand this type of rolling flex.
Figure 3	Torsional Flex: In torsional flex applications a longer lay length allows the conductors to float within the jacket, helping to minimize the compression or tensile load.
Figure 4	Variable Flex: Cables for variable flex applications should be designed to counter act the forces applied to the cable at the most severe point of flex.

One of the most important factors to consider when selecting flexing cables is the method used to determine comparative cable performance. Use of common test and statistical data collection and analysis methods in the comparison process is key to determining relative performance as well as the most appropriate product for a particular application. In order to determine how well a cable suits a specific application or to make a comparative decision based on relative performance prior to installation, physical laboratory analysis is recommended. Using benchmark data based on common process and utilizing statistical measurements and analysis techniques allows the designer to reliably predict flex life and overall system performance and apply a level of probability to these expectations.