Welcome to Gear Questions You’re Afraid to Ask, a GOLF.com series produced in partnership with Cleveland/Srixon Golf. We explore some of golf’s most misunderstood golf equipment terms, names and definitions in this week’s column.
We understand how confusing today’s equipment terminology can be, and it’s time to do a quick refresher on some of the more obscure and/or misunderstood elements of golf equipment terminology. . The list below is by no means exhaustive, but rather some of the names, definitions and acronyms that we think are the easiest to forget.
The bounce angle of your wedge plays a huge role in how it interacts with the sand or turf. In simple terms, the bounce angle is the angle formed by the sole and the leading edge of the wedge when the shaft is vertical. The higher the bounce angle, the higher the leading edge will sit on the ground, and the more the club will resist digging and “bounce” off the surface. Conversely, low-bounce wedges dig in more and are generally considered less forgiving.
Cast vs Forged:
A cast clubhead is constructed by pouring molten metal into a mould, which is then cooled and removed. A forged club is hammered from a single billet of steel until it is shaped into the desired shape. Most agree that wrought irons give a softer feel, but cast irons tend to have greater perimeter weighting capabilities for more forgiveness. There are exceptions to both rules however, and sometimes clubs are constructed of multiple pieces which are both cast and forged. Bonus: a milled club is a club cut from a single piece of metal.
COG stands for Center of Gravity (often referred to as CoG or simply CG) and is the precise point on the clubhead where it is in perfect balance. Where the CG is placed in the head is critical – forward CGs (toward the face) produce weaker launches and lower spin with less forgiveness; rear CGs produce higher launches with higher spin and more forgiveness. Additionally, higher CGs produce higher spin rates and lower launches, and lower CGs produce lower spin rates and higher launches. Now go ahead and read that again. We have to do this all the time.
COR (or simply COR) stands for coefficient of restitution, which is the ratio of energy transfer when two objects collide. A perfect transfer would have a rating of 1, but the maximum COR allowed by the USGA is 0.830. Most modern drivers from top OEMs all have COR ratings of 0.830, which is probably why you don’t hear it used in marketing materials like it was a decade ago. This is still important, however, especially since manufacturers are doing everything they can to maximize the allowed COR not only for drivers and woods, but also for irons.
Your clubs have built-in static loft, which is usually printed on your driver, woods, wedges, and sometimes irons. Dynamic loft is different – it’s the loft you create at impact, influenced by things like your angle of attack, the lean of your stick forward, the flex of your stick, whether the club is open or closed and where on the face the club makes contact with the golf ball. Club fitters who use launch monitors pay close attention to your dynamic loft at impact, often making adjustments to your clubs to improve the efficiency with which you hit the ball. Instructors take this into account as well, typically helping golfers decrease or increase their dynamic lofts for better ball striking.
EVA (or simply EVA) stands for Ethylene Vinyl Acetate, which is a combination of two children of plastics, and is the foam commonly found as the cushioning layer in today’s athletic and golf shoes. today. It is easy to shape, and shoemakers can make it to varying degrees of hardness. Here’s what you need to know, though. Shoes with cushioning that have higher levels of vinyl acetate than ethylene tend to be more durable and less brittle as they age.
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To understand how the gear effect works, you need to know what bulge and roll is. A driver’s bulge is the convex horizontal curvature of the clubface. The roll is the convex vertical curvature of the clubface. Combined, these bends influence how the ball spins across the face when struck away from the golf clubs center of gravity. When the ball hits to the toe, the ball goes to the right with an additional draw spin. When hit towards the heel, the ball starts left and spins with an additional fade spin. When hit low, the face rotation rate is higher. When hit high in the face, the spin rate is lower.
Ready to get technical? Here we are. Spin loft is the difference between your angle of attack (the direction in which the clubhead approaches the golf ball) and your dynamic loft at impact. The truth is, it’s a bit more complicated than that because the swing works in three dimensions, not two, but we’re here to keep it simple. Here’s why it’s important: Many golfers assume that the key to adding spin is hitting the ball. And while that’s partly correct, you also need to increase the angle between your angle of attack and your dynamic loft at impact, ie your spin loft. This is the secret for more effects.
A club’s sweetspot isn’t really a spot, it’s a specific point on the face where the maximum energy transfer occurs at impact. Equipment manufacturers sometimes claim their clubs have large sweetspots, but what they really mean is that they’ve made the area around the sweetspot more forgiving. And besides, the sweetpot is not always in the middle of the face. Sometimes it is biased in any direction depending on the design of the club and the location of the center of gravity.
Have you ever wondered why two titanium speakers don’t feel the same? This is partly because no two titanium alloys are exactly alike. The titanium used in speakers is actually an alloy, which is a mixture of several types of metals. Titanium in its raw form is quite strong, but mixing various metal compounds can actually make it even stronger and more flexible/less brittle.
You’ve probably heard of tungsten, but you may not know what it is. Tungsten is a heavier metal than lead and denser than steel, making it a prime choice for equipment manufacturers to improve a club’s internal weighting. It can be found in all types of clubs, usually to improve heel/toe weighting or to manipulate mass up or down or forward or back.
Urethane vs Ionomer
Golf balls typically have covers made of either a soft and tough urethane polymer or a more durable but firmer Surlyn ionomer. Urethane coated balls tend to cost more to manufacture, but also have that softer feel and higher spin performance that better players tend to prefer. For example, all models of Srixon Z-STAR have urethane covers, but Srixon goes a step further and adds SpinSkin technology, which features Slide-Ring (SeRM) material to increase friction and maximize spin on chips and pitches. The most affordable Q-STAR golf balls have ionomer coverage for added durability, but also have SpinSkin technology that digs deep into wedge and iron grooves, maximizing spin for more control and more stopping power.
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