A golf club is a club used to hit a golf ball in a game of golf. Each club is composed of a shaft with a grip and a club head. Woods are mainly used for long-distance fairway or tee shots; irons, the most versatile class, are used for a variety of shots; hybrids that combine design elements of woods and irons are becoming increasingly popular; putters are used mainly on the green to roll the ball into the hole. A set of clubs is limited by the rules of golf to a maximum of 14 golf clubs, and while there are traditional combinations sold at retail as matched sets, players are free to use any combination of legal clubs.
The most significant difference between clubs of the same type is loft, or the angle between the club's face and the vertical plane. It is loft that is the primary determinant of the ascending trajectory of the golf ball, with the tangential angle of the club head's swing arc at impact being a secondary and relatively minor consideration (though these small changes in swing angle can nevertheless have a significant influence on launch angle when using low-lofted clubs). The impact of the club compresses the ball, while grooves on the club face give the ball backspin. Together, the compression and backspin create lift. The majority of woods and irons are labeled with a number; higher numbers usually indicate shorter shafts and higher lofts, which give the ball a higher and shorter trajectory.
In 1979, TaylorMade Golf introduced the first wood made of steel. Even more recently, manufacturers have started using materials such as carbon fiber, titanium, or scandium.
Although most "woods" in golf are constructed from various metals, the term "woods" persists to characterize their general shape and intended use on the golf course. Contemporary woods commonly feature a graphite shaft paired with a predominantly hollow head made of titanium, composite materials, or steel. This design emphasizes light weight, enabling faster club-head speeds. Woods, being the longest and most powerful clubs, typically consist of three to four options in a set. They are primarily utilized from the tee box and, on longer holes, may be employed for the second or even third shot. The largest wood, often referred to as the driver or one wood, is frequently crafted from hollow titanium and incorporates feather-light shafts.
The length of the woods has been increasing in recent decades, and a typical driver with a graphite shaft is now long. Woods can also have very large heads, up to in volume, the maximum allowed by the USGA in sanctioned events; drivers with even larger club-head volumes are available for long-drive competitions and informal games. The shafts range from senior to extra-stiff depending upon each player's preference.
As with woods, "irons" get their name because they were originally made from forged iron. Modern irons are investment-cast out of steel alloys, which allows for better-engineered "cavity-back" designs that have lower centers of mass and higher moments of inertia, making the club easier to hit and giving better distance than older forged "muscle-back" designs. Forged irons with less perimeter weighting are still seen, especially in sets targeting low-handicap and scratch golfers, because this less forgiving design allows a skilled golfer to intentionally hit a curved shot (a "fade" or "draw"), to follow the contour of the fairway or "bend" a shot around an obstacle.
Most chippers have a loft greater than 10 degrees, which is the maximum loft permitted by the Rules of Golf for a club to be classed as a putter, so these clubs are actually classed as irons. To be legal for sanctioned play, a chipper cannot have any feature that is defined in the rules as allowable only on putters, e.g. two striking faces or a flat-topped "putter grip". This disqualifies many chipper designs, but there are some USGA-conforming chippers, and non-conforming designs can still be used for informal play.
Despite the strength of hickory, the long-nose club of the mid nineteenth century was still prone to breaking at the top of the back swing. The club heads were often made from woods including apple, pear, dogwood, and beech in the early times until persimmon became the main material. Golf clubs have been improved and the shafts are now made of steel, titanium, other types of metals or carbon fiber. The shaft is a tapered steel tube or a series of stepped steel tubes in telescopic fashion. This has improved the accuracy of golfers. The grips of the clubs are made from leather or rubber.
Shafts are quantified in a number of different ways. The most common is the shaft flex. Simply, the shaft flex is the amount that the shaft will bend when placed under a load. A stiffer shaft will not flex as much, which requires more power to flex and "whip" through the ball properly (which results in higher club speed at impact for more distance), while a more flexible shaft will whip with less power required for better distance on slower swings, but may torque and over-flex if swung with too much power causing the head not to be square at impact, resulting in lower accuracy. Most shaft makers offer a variety of flexes. The most common are: L/W (Lady/Women's), A/I (Soft Regular, Intermediate or Senior), R (Regular), S (Stiff), and X (Tour Stiff, Extra Stiff or Strong). A regular flex shaft is generally appropriate for those with an average head speed (), while an A-Flex (or senior shaft) is for players with a slower swing speed (), and the stiffer shafts, such as S-Flex and X-Flex (Stiff and Extra-Stiff shafts) are reserved only for those players with an above average swinging speed, usually above . Some companies also offer a "stiff-regular" or "firm" flex for players whose club speed falls in the upper range of a Regular shaft (), allowing golfers and club makers to fine-tune the flex for a stronger amateur-level player.
At impact, the club head can twist as a result of torque applied to the shaft, reducing accuracy as the face of the club is not square to the player's stance. The ability of a shaft to twist along its length due to this torque is fundamentally a function of the flex of the shaft itself; a stiffer shaft will also torque less. To counter torque in more flexible shafts, club makers design the shafts with varying degrees of torque through their length, particularly along the thinnest part of the shaft where it joins with the club head. This results in a point at which the shaft is most flexible, called the "kick point"; above that point the increasing diameter of the shaft makes it more rigid, while below that point the shaft is reinforced internally to reduce torquing of the club head. Shafts have typically been classified as having a low, medium or high kick; a low kick means the shaft will store energy closer to the club head, which means the club head can twist more but also allows for higher club head speeds. A high kick shaft will store energy closer to the grip; such a shaft will feel firmer when swinging it and will give better control over direction, but the same strength swing will flex the shaft less, which will reduce club-head speed.
Widely overlooked as a part of the club, the shaft is considered by many to be the engine of the modern club head. Shafts range in price from a mere US$4 to over US$1200. Current graphite shafts weigh considerably less than their steel counterparts (sometimes weighing less than for a driver shaft), allowing for lighter clubs that can be swung at greater speed. Beginning in the late 1990s, custom shafts have been integrated into the club-making process. These shafts will, within a given flex rating, address specific criteria, such as to launch the ball higher or lower or to adjust for the timing of a player's swing to load and unload the shaft at the correct moments of the swing for maximum power. Whereas in the past each club could come with only one shaft, today's club heads can be fitted with dozens of different shafts, each with slight variation in behavior, creating the potential for a much better fit for the average golfer.
Re-gripping used to require toxic, flammable solvents to soften and activate the adhesive, and a vise to hold the club steady while the grip was forced on. The newest replacement kits, however, use double-sided tape with a water-activated adhesive that is slippery when first activated, allowing easier installation. Once the adhesive cures, it creates a very strong bond between grip and shaft and the grip is usually impossible to remove without cutting it off.
The club head must have only one striking face, except that a putter may have two such faces if their characteristics are the same, and they are opposite each other.
Page 127 of the USGA rules of golf states:USGA rules of golf, p. 127.
A putter is a club with a loft not exceeding ten degrees designed primarily for use on the putting green.
Therefore, any double sided club with a loft greater than 10 degrees is not legal.
The most common set of men's clubs is:
The above set is only 12 clubs; these (or equivalent hybrid substitutes) are found in virtually every golf bag. To this, players typically add two of the following:
Women's club sets are similar in overall makeup, but typically have higher lofts and shorter, more flexible shafts in retail sets to accommodate the average female player's height and swing speed.
Variations on this basic set abound; several club options usually exist for almost any shot depending on the player's skill level and playing style, and the only club universally considered to be indispensable is the putter. Some consider the modern deep-faced driver to be equally irreplaceable; this is cause for some debate, as professional players including Tiger Woods have played and won tournaments without using a driver, instead using a 3-wood for tee shots and making up the difference on the approach using a lower-lofted iron.
The most common omissions are the "long irons", numbered from 2 to 5, which are notoriously difficult to hit well. The player can supplement the gaps in distance with either higher-numbered woods such as the 5 and even the 7-wood, or may replace the long irons with equivalently-numbered hybrid clubs. If hybrids are used, higher-lofted woods are often omitted as redundant, but ladies' and seniors' sets commonly feature both hybrids and high-lofted woods, omitting the long irons entirely in favor of the lofted woods, and replacing the mid-irons (5–7) with hybrids. The combination allows for higher launch angles on the long-distance clubs, which gives better distance with slower swing speeds. Where a club is omitted and not replaced with a club of similar function, players may add additional clubs of a different function such as additional wedges.
While 14 clubs is a maximum, it is not a minimum; players are free to use any lesser number of clubs they prefer, so substitutions for the common omissions above are not always made; a player may simply choose to play without a 5-wood or 2–4 irons, instead using a 4-wood and moving directly to their 5-iron as desired distance decreases (a 4-wood in a skilled golfer's hands averages 200 yards; a 5-iron in the same player's hands would be about 160, which is a large gap but not unplayable). Other clubs may be omitted as well. On courses where bags must be carried by the player, the player may take only the odd-numbered irons; without the 4, 6 or 8 irons (the 3 is sometimes removed instead of the 4) the bag's weight is considerably reduced. Carrying only a driver, 3-wood, 4-hybrid, 5-7-9 irons, pitching and sand wedges, and a putter reduces the number of clubs in the bag to 9; this is a common load-out for a "Sunday bag" taken to the driving range or to an informal game. A skilled player can usually overcome the lesser selection of club lofts by reducing their swing speed on a lower-loft iron and/or placing the ball further forward in their stance to get the same carry distance and/or launch angle as the next higher loft number. Another increasingly common informal format is a deliberately low upper limit such as four clubs, or three clubs plus putter, with a typical load being a wood or hybrid, middle iron, wedge and putter, although often with significant variation between players with regards to which specific clubs are favored in each role.
The overarching principle of club design used by both authorities is defined in Appendix II-1a, which states: "The club must not be substantially different from the traditional and customary form and make. The club must be composed of a shaft and a head and it may also have material added to the shaft to enable the player to obtain a firm hold (see 3 below). All parts of the club must be fixed so that the club is one unit, and it must have no external attachments." In addition, Appendix II-4a states, regarding club heads, that "the club head must be generally plain in shape. All parts must be rigid, structural in nature and functional. The club head or its parts must not be designed to resemble any other object. It is not practicable to define 'plain in shape' precisely and comprehensively."
These two rules are used as the basis for most of the more specific rules of Appendix II, including that no club may have a concave face (1931) and various rules defining what is "traditional" about the shapes of specific clubs, while allowing for the progression of technology. The "traditional and customary" rule was originally used to ban the introduction of steel club shafts (patented in 1910), as that material was not traditional for shafts; that specific ban was rescinded in 1924 by the USGA (the R&A would continue to ban steel shafts until 1929), USGA History - 1911-1930 and steel would become universal until the development of graphite shafts whose introduction was less controversial. The "plain in shape" rule was more recently bent to allow for non-traditional driver club head shapes, such as squares, as a compromise to club-makers after imposing and enforcing a volume limit on these same club heads.
Many recently developed woods have a marked "trampoline effect" (a large deformation of the face upon impact followed by a quick restoration to original dimensions, acting like a slingshot), resulting in very high ball speeds and great lengths of tee shots. As of 1 January 2008, the USGA and R&A have settled on a regulation that limits the acceptable "trampoline effect" to a coefficient of restitution (COR)—a measurement of the efficiency of the transfer of energy from the club head to the ball—of 0.830.
Other large scale USGA rulings involve a 1990 lawsuit, and subsequent settlement, against Karsten Manufacturing, makers of the PING brand, for their use of square, or U-grooves in their immensely popular Ping Eye2 irons. The USGA argued that players who used the Eye2 had an unfair advantage in imparting spin on the ball, which helps to stop the ball on the putting greens. The USGA utilized John L. Saksun, founder of Canadian golf company Accuform Golf, as a consultant to set up methods of measuring the unique grooves and determining PING's compliance with the rulings. Saksun, by proposing a cost-effective solution to help PING change the design of subsequent Eye2s, saved PING hundreds of millions. PING subsequently withdrew their US$100 million lawsuit against the USGA. Ping’s older clubs were "grandfathered in" and allowed to remain in play as part of the settlement. However, the USGA has begun phasing in a ban on square grooves in golf. Manufacturers were required to discontinue noncompliant clubs by January 1, 2011. According to the USGA, as January 1, 2010, professional golfers on one of the top tours, or those attempting to qualify for one of the three Open Championships (since then four) will need to use new conforming wedges (those without square grooves). Moreover, those who plan to qualify for any other USGA championship (Amateur championships—under 18, Amateur, over 25, and over 50 in both sexes, and four-ball, along with international team championships), will need new conforming wedges by 2014. In addition, this regulation includes IGF and USGA-sanctioned regional amateur events as well, as a "condition of competition". Wedges that conform to the new standard are often marketed as "CC" or "Condition of Competition" wedges; this moniker is likely to fall into disuse as players upgrade clubs and the use of non-conforming irons diminishes.
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