Final answer:
The old standard for circular hand grip sizes was about 5 inches side-to-side and 7-8 inches deep, but newer studies suggest a maximum of 8 inches side-to-side and up to 15 inches deep for better ergonomics.
Step-by-step explanation:
When designing a circular hand grip, ergonomics plays a vital role in determining the appropriate size for comfort and usability. Traditionally, a rule of thumb for the cross-section of hand grips was approximately 5 inches side-to-side and 7-8 inches deep. However, newer ergonomics research suggests that a hand grip could benefit from being up to 8 inches in diameter side-to-side and 15 inches in diameter deep for optimal grip.
The minimum cross-section should ensure that the grip is not too small to hold comfortably, whereas the maximum should prevent the grip from being too large and causing strain to the user's hand. Therefore, it can be concluded that hand grips should have a minimum cross-section of approximately 5 inches and could have a maximum cross-section of about 8 inches, with depth consideration ranging from 7 to 15 inches based on the latest ergonomic standards.