Tennis players of all levels have gone crazy for spin in recent years! With the latest racquet and string technology along with younger players trying to replicate the modern swings of Rafael Nadal and Novak Djokovic, players are trying to maximize the amount of spin in their games as best as they can.
Our TW University Professor Crawford Lindsey has done extensive testing on how spin is produced during a shot, and what factors apart from the stroke itself aid or hamper the production of spin. At contact, the ball hits the stringbed and moves the main strings (the strings that are horizontal at impact), sliding them out of position vertically against the cross strings. As the ball leaves the strings, the main strings snap back into their original position. A string’s ability to slide and snap back efficiently is what our TW Professor concluded to be the biggest difference between strings in terms of their spin potential. Therefore, the further the main strings can stretch during this process, the greater the snap back force is, and thus the more spin you can generate.
Our TW Professor found that there are two primary forces that come into play when determining how much a string will slide and stretch during this process. He found that both the friction between the ball and the strings as well as the friction between the strings themselves (mains and crosses) both affect how much a string can stretch at impact.
First, the greater the friction between the ball and the strings, the more the ball can grab and sink into the strings, thus being able to stretch it as far as it can. If the ball slides off the strings and doesn’t grab well, it can’t impart as much force on the string in order to stretch it out of position. Therefore, the greater the string-to-ball friction (how well the string grabs the ball), the more spin potential.
Second, the slicker the surface of the strings are, the easier it is for the strings to slide on themselves when the ball hits the stringbed. The easier the strings slide, the more snapback that can be created. The more friction there is between the strings preventing movement, the more difficult it is for the strings to stretch and snap back efficiently. Therefore, the less string-to-string friction there is, the more spin potential.
Generally, polyester strings are the slickest and slide the best on themselves. Polyester strings that are shaped or textured usually grab the ball the best too. A slick polyester that can grab the ball well will generally generate the most topspin.
TW University has created a “Spin Potential” ratio (ball friction / string friction) to quantify which strings are the most spin-friendly. The strings that combine high ball-to-string friction while still maintaining a slick surface to slide on itself (low string-to-string friction) have the highest Spin Potential numbers. Check out our TW University String Finder link to see which strings are the most spin-friendly. Also, make sure to check out our TW University website for all the research and writings that our in-house professor Crawford Lindsey has done.
Thanks for reading!