Cavity-backed irons first hit the golf world with the Ping line of founder Karsten Solheim. In the 50 years since, virtually every club manufacturer has produced its own line of cavity backs, so called because of the mass removed from the back of the club head.
This allowed the club to move weight to the outer edges of the face. It’s not a stretch to say this perimeter weighting revolutionized the game, as it made irons much more forgiving than the blades that were golfers’ only choice until that point.
Blades, sometimes called “muscle back”, are much more difficult to hit. Although this is beginning to change, many professional and top-notch amateurs continue to use blades. This may have as much to do with a badge of honor than any advantage blades might offer.
Since blades are too difficult to hit consistently for even mid-handicappers, using them is a signal to fellow golfers that you are a good golfer.
Let’s compare the two types of irons in a number of areas to see the differences.
Cavity-backed irons are generally longer than blades. Almost every player will hit the ball more consistently with cavity backs. The perimeter weighting yields a larger sweet spot with less flexing of the club face at impact. This means off-center shots will travel straighter and farther.
If you took a poll of experienced golfers, a large majority would likely tell you that blades offer greater control than cavity backs. Low handicappers and professionals love the ability to hit a variety of shots depending on whatever situation they face.
Whether it’s the need to keep the ball low under tree branches, or go over the tree, hit a draw to escape trouble, or slice it around a hazard, blades are the way to go.
Or are they? This belief could be just a remnant of old ideas. Certainly, there is no proof that it is true, merely anecdotal evidence in a game where tradition is still embraced and change comes slowly.
More and more professionals are turning to cavity backs. These players’ livelihoods depend on shaping the ball as needed. Unlikely that they would make that choice if blades were so superior in this regard.
Blades are generally considered to offer more feel than cavity backs. Again, this is the sort of thing that is hard to prove. There is, however, some logic to this belief.
Blades are smaller and have a lower moment of inertia (more on both in a bit), meaning you will definitely notice if you miss the sweet spot. For good golfers, this could be a plus since they rarely hit off-center shots. Greater feel likely is the biggest advantage for blades over cavity backs.
Cavity backs have a larger club head to facilitate the perimeter weighting they are known for. Blades are both smaller and thinner, especially on the leading edge.
The larger club head on cavity backs gives them more of a blocky look. Certainly, the looks of the first Ping clubs was distracting for some golfers who had difficulty getting past it. Today’s cavity backs are more attractive than those of the past, especially since golfers have had many decades to get used to them.
There is no denying the beauty of blades. This aesthetic advantage should not be totally dismissed. Standing over a shot holding a bladed iron could give a small number of golfers more confidence. Golf is at least as much a mental game as a physical one.
Of course, most golfers will get more confidence from cavity backs after hitting the two, despite the disadvantage in the looks department.
This is far and away the main reason cavity backs have become so popular. The perimeter weighting means the club will flex less upon impact for off-center shots. That means those shots will have more speed coming off the club, going farther and straighter to boot.
Even the most devoted fan of blades would likely admit to this. Some blades may have a bit of perimeter weighting, although the amount is limited and far less than cavity backs. Blades simply cannot compete in this area.
Solheim’s other innovation was to make his cavity-backed irons in a cast process. Almost all cavity backs are made using casting, where molten metal is poured into a mold. The design of cavity backs almost demand a cast process, as the clubs have size and shape require it.
Most blades are forged, carved from a single piece of metal. This process is more expensive and likely superior to casting. The simpler design of blades allow for the forging process. The result is a beautiful iron.
The two specifications that are most important here are center of gravity and moment of inertia. Cavity backs are the clear winner in both areas.
Cavity backs are both wider and larger, allowing for more weight to be added near the bottom of the club. This produces a lower center of gravity and that gives golfers an edge in getting the ball airborne.
Moment of inertia is a measure of how much a club twists at impact. Less twisting is better and the perimeter weighting of cavity backs gives them a higher MOI. Higher is better here and that makes cavity backs much more forgiving than blades.
By this time, you may be wondering why anyone would continue to use blades. For a large majority of golfers, there is no reason to play anything but cavity backs. The huge edge in forgiveness is too important for any but the best golfers.
Old ideas die hard in golf, and blades are not likely to go extinct any time soon. But they are already rare at any local municipal course, and are becoming more so on the professional tour.