A cable pulley should support the cable without creating excessive bending or side pressure. Choose a wheel diameter that respects the cable manufacturer’s minimum bending radius and a groove wide enough to avoid pinching the sheath.
Rated load is equally important. The force on a corner pulley can be much higher than the line tension, especially at sharp changes in direction. Frames, bearings and fixing points should therefore be selected for the actual route geometry rather than cable weight alone.
For manholes, trenches and tower work, consider how the pulley will be installed and removed. Lightweight aluminum wheels improve handling, while steel frames and sealed bearings are often preferred for demanding outdoor projects.