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The Basics – How Golf Clubs Work – Part I

Cavity back or muscle back? Thick sole or narrow sole? Offset or no offset? There is just so much to know when buying golf clubs and just when you think you know everything, something new comes out.
Fad technologies come and go but there are some really basic ideas that have withstood the test of time. Most consumers that I talk to can identify most technologies but do not always understand what they do. Before you buy golf equipment, make sure you at least understand the basics.

Cavity Back vs. Muscle Back

This is probably one of the most basic technologies in golf, and one of the easiest to understand. The distribution of mass behind the club face can radically alter forgiveness and ball flight. A cavity back is created when the majority of the weight is pushed to the outside of the head, thus creating an empty cavity. So it basically means this, the bigger the cavity, the more forgiveness. A muscle back is the opposite. It doesn't have a cavity and is filled in across the whole back. Muscle backs or blades are designed for the better player and require a good ball striker to make them work.

There are pros and cons to both of these designs. The biggest pro of a cavity back is forgiveness. 99% of golfers should be playing some sort of cavity back golf club. This doesn't mean that everyone needs a massive cavity in their golf clubs or that you need all cavity back clubs (a combo set is a great idea for a good ball striker).

Muscle back irons are designed for someone that doesn't miss hit the ball. There is a lot of weight right behind where you want to hit the ball. This is great if you make solid contact every time, more weight behind the ball means that it is easier to control the ball trajectory and ball movement. A good player likes this because they focus on getting the ball to do what they want it to do. The downside to this is that there is no cavity to provide forgiveness. You can feel miss hits a lot more and the ball flight suffers!

It's really a game of give and take when you talk about cavity back vs. muscle back. Should you give up forgiveness for playability? Do you need a huge cavity when you are a really good ball striker? Club manufactures have started to bridge the gap between these two types of irons, more and more companies now have a players iron with a small cavity. These irons look like a blade when you look down on them (they have a thin top line and the cavity is not visible) but they have a small cavity for some forgiveness. Not everyone is going to hit the ball the same all the time. Even Tour players miss hit, so why not feature a small cavity for the occasional miss hit? The club that really got this trend going as of late was the Titleist 962. There is now a steady stream of these irons coming to market, Cleveland TA2, Cleveland TA3, TaylorMade LT, pretty much all Hogan irons, and so on. The combo set is another popular way of bridging the gap and getting the best of both worlds. Cavity backs for the longer irons, where there is a better chance of miss hitting the ball. Muscle backs for the shorter irons, where there is less chance of miss hitting the ball and a greater demand on ball control.

Get an iron that helps you, don't buy a club that looks good but does nothing for your game. If you need a cavity back, then buy a cavity back. I see lots of people buying whatever their favourite pro uses, but guess what, they're better than you!

Center of Gravity

Ok kids, it's time for a physics lesson. Here is a golf ball. Here is a golf club. A large amount of the club's mass falls below the center of gravity of the ball. What will happen when the golf club hits the golf ball? Well, if struck properly, the ball will get up in the air quickly. Most golfers need a club with a low center of gravity because they need to hit the ball higher.

So how can a company lower a golf club's center of gravity? There are a few popular ways to do this. The first is making the sole of the golf club really thick. Think about it, more material in the sole means more weight. Some companies will also try to make the top line lighter, whether it is by making it thinner or using a technology like Cleveland's Micro Cavity. You may also see different metals used to weigh down the sole. Tungsten is probably the most popular metal for something like this. It is far heavier than stainless steel and a small amount of it in the right place can drastically alter how a golf club performs. Tungsten is 2.5 times heavier than stainless steel and 4 times heavier than titanium. Just because a club appears to have weights added to the bottom doesn't mean that they will work. A lot of cheaper clubs will have things that look like weights but they are nothing more than a cosmetic addition.

The center of gravity in a wood is very similar to that of an iron. For a wood to create the highest ball flight the center of gravity must be in the back and at the bottom. Think of a club like the TaylorMade R5 Dual. Notice where the two weight screws are? These two screws put the center of gravity low and deep, creating a high ball flight. The distribution of weight in a wood is a bit different. The crown of a wood is incredibly thin, that's why they dent so easy! Weight can be taken out of the walls, sole or crown of a club and redistributed to other places to alter ball flight. Most woods designed for a mid to high handicapper will have more weight on the bottom (to create a high ball flight) and the heel (to help close the face at impact to reduce a slice). The trick in making a wood is allowing for the most distribution of weight without jeopardizing the structural integrity of the club. Golf companies are now turning to new materials to make the redistribution of weight easier. Some of the more recent clubs have a composite crown which is more durable and basically weighs nothing. There has also been a trend towards interchangeable weights, a good idea for those with a consistent swing.

Materials Used In Golf Clubs

Any idea what the Rockwell Hardness Scale is? Probably not. Don't worry though because you are not alone. The Rockwell Hardness Scale measures the hardness of a metal, I won't get into how it is tested but this scale is used all the time in golf club construction. You may have run into materials like 431 Stainless or 17-4 Stainless while shopping for clubs. But what does it mean?

The Rockwell Hardness Scale is used for all metals but there are a few we should key on that are often used in the construction of golf clubs. The table below contains twelve of the most commonly used metals in golf clubs. They are ranked from softest to the hardest (top to bottom).

Material and it’s Hardness

Aluminium = B50-60

Carbon Steel = B60-70

304 Stainless = B75

Beryllium Copper = B70-80

431 Stainless = C18-25

100% Titanium = C24-28

6-4 Titanium = C32-36

17-4 Stainless = C34-38

450 Steel = C36-40

15-5 Stainless = C36-44

Beta Titanium = C40+

Maraging Steel = C45-55

Many clubs designed for the better player will be made from 431 Stainless. Beryllium Copper really isn't used much anymore, partly because it is too soft and dings up really easily. The most common material for irons is probably 17-4 stainless. It is slightly harder (more durable) but is soft enough that it will provide some feel. Maraging Steel was pretty big a few years ago and was primarily used in the faces of woods. Aluminium is used in starter sets, mainly because of its cheap cost. These starter sets will not be as durable as a steel set but most beginners don't swing hard enough to cause major damage to an iron. Carbon Steel is popular in wedges because of its soft feel but its durability is a concern.

You will also notice a few different kinds of titanium on the chart too. Titanium is a trade off, the harder the titanium, the more it will c
ost. Some companies will even use two types of titanium in a club head, 6-4 Titanium body with a Beta Titanium face. This allows them to only use the more expensive titanium where it matters, thus lowering the cost. Watch for some cheaper clubs that use a Titanium Alloy or Titanium Matrix. This is a cheap material that consists of only a small amount of titanium but enough that the company can put Titanium in the name. Like anything else, you get what you pay for here.

There is Part I of "How Golf Clubs Work". Next time we will look at a few other common club making ideas including the dreaded offset. If you have any questions, feel free to email us at comments@sirshanksalot.com . Until next time!

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