In Game Theory, a Nash Equilibrium is defined as:
A stable state of a system involving the interaction of different participants, in which no participant can gain by a unilateral change of strategy if the strategies of the others remain unchanged" - Google Gemini
What on earth does this have to do with squash racquets?!?!
Well, when we think about the development of squash racquet, we can simplify "the game" into two competing strategies: an oval shaped frame with a bridged throat or a V-Neck with a very small throat. In our previous blog post, we examine how a V-Neck shape lends itself to power in singles, but a series of factors lead to a wider oval-frame shape preference in doubles.
The Sweet Spot
First, it's important to recognize that the maximum allowable surface area of a squash racquet is 500 cm², we will come back to this in a moment. But depending on the shape, the sweet spot length and width varies as you can see in the diagram to the right.
The Shahtoosh Cut 1.0 has a dense sweet spot that produces significant recoil and added power due to V-neck throat and the trampoline effect.
Due to this power advantage, the width of the Shahtoosh Cut 1.0 is constrained by the 500 cm² limit, which in turn produces a slightly less wide sweet spot. Power is very important in doubles, but a thinner throat create significant accuracy loss. At some point, this loss outways the gain in power for a few reasons. As shown in the image to the left, any small deviation in ball trajectory off the racquet in doubles is amplified due to the 13' court length difference on a doubles court. Therefore, a wider sweet spot provides a player a larger "room for error" or area of control on contact with the ball. But you cannot go wider without compromising on width due to the 500 cm² constraint, thus imposing a shorter vertical string pattern (reducing power).
Strength of Frame
A wider sweet is one reason for a wider frame in doubles, but, the larger factor is shape difference is frame strength. In singles squash, the amount of energy absorbed into the frame on each shot is much lower than in doubles squash for a few reasons.
The hardball in doubles means the ball is striking the racquet with substantially more force. Any teardrop racquet is going to be significantly weaker, especially on the lower side of the frame and the throat where there is less support and energy concentrates and reverberates on impact.
Tactical Components
Finally, basic tactics of doubles purport that pushing forward and maintaining front position is beneficial as it allows your team to cut off the ball and hit to the front while your opponents are behind you.
Very simply, as seen in the diagram to the left, pairing A-B is in an advantageous positions compared to pairing C-D. If it is paring A-B's turn to hit, they can easily hit a reverse boast to the front court out of range of retrieval for pairing C-D. But what does this have to do with frame width and shape?!?!
The trouble with cutting of the ball like pairing A-B is you cut off time to react to pairing C-D's shot, meaning you must react quickly, which increases the probability of a shot missing the the sweet spot and becoming a complete miss hit...which almost certainly sets you up to lose the point. A wider sweet spot again provides more room for error.
A wider sweet spot, strength of racquet frame, and tactical factors --- all contribute to a Nash Equilibrium in doubles where wide-framed, bridged-throat designed racquet is preferred compared to a narrower, more powerful V-Neck counterpart. With this said, in singles, this dense sweet spot lends itself to better touch and power.