As a follow up to the All Wedges Are Not Created Equal blog that measured the variance in performance between a number of manufacturers wedges it's worth delving into the subject of spin generation a little with a brief review of the USGA literature that is freely available and commonly held beliefs.

What are the technological factors that effect spin?

- The roughness of the flat surface between the grooves

- The sharpness of the top edge and/or the type of grooves

- How far apart the grooves are positioned

- The depth of the grooves.

The interaction that creates spin is quite simple, it is one that creates the most friction and therefore the most spin. At lofts of 40º and under the interaction is mostly sticking and no slipping occurs, the friction force is the same with both smooth and rough surfaces according to Chou, Liang and Yang (Science and Golf II: Proceeedings of the World Scientific Congress of Golf II)

This leads us on to the research conducted by the USGA over a period of years prior to the rule change regarding groove technology, available here USGA Research. The interim paper notes that prior research has found that there is no difference made by groove configuration and face treatment and proceeded to test both the U & V groove types in dry conditions concluding that there was no difference once again.

However during the benchmark player testing there was found to be a difference between modern equipment and old V grooves and balata balls that spun more that any modern equipment combination. From the rough however it was found that the U grooves had the potential to spin MORE than from the fairway! 

The study also concluded that the edge radius or the 'sharpness of the edge' is a contributor to spin but the closer towards a V Groove shape it became the significance reduced to almost none.

Groove spacing was also found to be a significant contributor regardless of groove type.

The type of milling was found to have no significant influence on spin rate from the rough except for an extremely rough surface.

So the question remains as to what was responsible for the often huge performance gaps for spin generation between wedges included in the testing from the previous blog entry. If all the above were bulletproof it would fair to say the performance should be very similar throughout when using the same player, in the same conditions, even allowing for some technical variance. 

We're excited to be planning some testing next month that will include the use of grooved and non grooved wedges from a variety of lies and distances. While it will not be as scientifically sound as the USGA's (expensive) testing it should provide some insight into this fascinating topic in the real world sense.

Using the data collected from a wedge testing session last summer I’m going to illustrate a few key points that might help improve your wedge game through choice and maintenance of equipment.

A group of wedges (56º) from a variety of manufacturers were tested from a distance of 70 yards from two types of lies, tight fairway and 2 inch rough. Spin rate and launch angle were measured using a Foresight GC2,  the wedges required a minimum number of 5 shots from which the averages and standard deviation were taken. A spin retention value was also calculated to measure the diminishing performance from the rough.

The average spin rate from 70 yards on a tight lie was 7130rpm but the variance went from a low of 3573rpm to a high of 8910rpm, as you can see from the mean average the drop in performance from a low performing wedge was significantly greater than the gain from a high performing wedge. The higher performing wedges tended to have a better quality of milling, score lines and extra grooves to provide that advantage.

The correlation between launch angle and spin rate was somewhat linear, for example the lowest spinning wedges were around the 4000 mark and launched at 32º. Wedges spinning at 5000rpm launched at 30º, 6000rpm at 28º all the way to the high 8000’s launching at 24º. Club delivery was very consistent throughout illustrating the importance of friction to launch.

Spin retention from the rough was quite revealing with the average wedge maintaining 30% of it’s fairway spin number when being hit from 2” rough. The top performers in this category maintained approx 50% while the poor performers only maintained approx 20%.

Combining these two parameters gives a good idea of which wedges are the overall top performers and should you get chance to test wedges on a launch monitor of some kind are two measures I’d recommend looking at.

We also conducted a test comparing year old wedges of the same type versus brand new, the old had seen a couple of dozen rounds and some range use but nothing excessive. The spin loss and related higher launch was significant at over 50%.

If you’re going to work towards a tour calibre wedge game it’s vital that you equip yourself properly, if you don’t it will be impossible to control launch, spin effecting trajectory leading to poor distance control.

JR