Is iron spin ratio still accurate given stronger lofts

[sirparalot]

It has been a longstanding belief that ideal iron spin is considered to be the number on the iron multiplied by 1000. So a 7 iron should spin at approximately 7000rpm. With the lofts of clubs getting stronger and a focus on higher launch lower spin does that ratio still hold true. Should I expect a 27 - 28 degree 7 iron to spin at 7000 rpm compared to the old standard of approx 36 - 37 degrees for a 7 iron. Given the new stronger loft standard what launch and spin numbers should an average golfer with a 75mph 7 iron swing speed expect to see?? If todays 7 iron is closer to a 5 iron loft from years back is 5000 spin a good number??? In my current look for new irons I am coming nowhere close to the iron number multiplied by 1000 standard that has been used in the past. Would love to hear from some fitting experts on what they currently target for an average golfer.

[trhode]

Iron spin has always been based on loft regardless of what number the manufacturer decides to stamp on the bottom. When 7 iron spin was considered good around 7000rpm, average loft was around 36°. Based on that, you should be able to determine a decent spin rate for modern heads. But, from a fitting perspective, there is more to just the loft. Like, how is the spin being generated, or not generated? Some players need more spin, some need less. Angle of attack, dynamic loft, peak height, decent angle are all factors to be considered when determining how much spin a player needs or doesn’t need.

[Stuart_G]

Nothing's changed. It's always been a bad perception of what ideal spin should be and it still is, especially for am's. It's just a really bad misinterpretation of the old Trackman data posted for the PGA (and LPGA) tour averages. An average is not the same thing as an ideal value. There is not now, nor has there ever been a generalized 'ideal' or optimal spin for irons that applies equally to all players. Even among the pros, different players with different swing speeds and different deliveries can have completely different needs for spin to get the best results for their swing.

Iron loft is about trading off distance and distance gaps vs distance control (amount of roll out and ability to hold the greens on the approach) and finding the right balance between the two for the particular players swing.

[sirparalot]

Thanks for the info. I was hitting a 27.5 degree 7 iron. It was launching at 17-18 degrees, spinning around 4000, peak height at 70 feet and descent angle at 40 degrees. This was all indoor on trackman and I am concerned with ability to hold greens and was wondering if the numbers were appropriate for 75 mph club and 105 mph ball speed.

[Stuart_G]

Hitting off some types of mats can significantly reduce spin (and increase launch) compared to hitting off of grass. Either wait until you can get some numbers hitting off of grass - or you can try to tee the ball up a little bit and then see what happens.

Mats VS Grass – What’s the Difference?

 

[Ger21]

I watched some fitting videos yesterday where they mentioned you can give up a little spin, if you can launch it higher and get a steeper descent angle. But they were still talking about 6000+ rpm, with a 45° descent.

 

However, your 27.5° 7 iron is the same as my 5 iron, so I'm not sure how you can find 2000-2500 rpm more spin than I can get with my 5 iron.

[trhode]

When fitting an iron, I always look at the carry vs total distance with the landing surface set to medium. More than 2 yards difference is no bueno. 1 yard is pretty ideal imo.

[WristySwing]

WIth a 75mph swing speed with a 7i you will likely never be able to get to 7000 RPMs out of a 7i, even if it is traditionally lofted around 34-36*. Hitting down on the ball creates spin, as does ball speed. That's why you see so many longer hitters struggling with excessive spin and claiming no matter what they hit the spin is high. It's because the ball speed and peak height and all that fun stuff gets higher with faster speeds. The more important metrics than spin are descent angle and peak height. If you can match your peak height to your swing speed, so roughly 75 feet, have a descent angle around 46* and have spin in the mid-high 4000s you will be fine on most golf courses that us recreational players are on. Spin is so tough to accurately measure, as Stuart mentioned since mats can affect this, moisture conditions of the ground, wind direction, elevation, strike point on the face, golf ball, and humidity can all influence how much spin is imparted and this can vary day to day just by the player and weather conditions and definitely varies course to course.

A better measure for most amateurs would be to have about a 600-800 RPM spin differential between clubs if you take the general rule of thumb that roughly 150-200 RPMs of spin per degree of loft is true per iron, all else being the same. So hybrids spin around 4200 RPM as a solid base line, that puts a 26* iron to spin around 4800 RPM, a 30* iron at 5400 RPM, and so on. As long as the 26-28* iron is getting the peak height and descent I discussed above and the strike is clean, you are going to be okay and likely have little stress about holding greens. This is assuming a loft difference of 4* per club.

[Howard_Jones]

Thats only one of many stupid rules of thumbs, and not even Trackmans Averages has that number, so someone made a cherry pick back in time, and since then we have been stuck with that myth.

If that was "ideal" we should have seen a LINEAR progression ratio to spin value of 1000 pr iron, but the fact is that the T.A. numbers is not even close to that, and lower than 700 rpms from iron to iron as average. (see the chart below, all numbers ripped from Trackman PGA and LPGA average)

Descent angle and stopping power is what this really is about, and for high spin players, prevent ballooning into the wind, but as a general guideline, players at LPGA club speed level should have a descent of 45 or steeper and players at PGA level up at about 50*

Trackmans own testing has shown us that the moment the ball has used up the energy that keeps it in the air and it starts falling down, ball speed left is about the same, no matter what the speed was out from the tee, so what we should pay attention to is Apex and by that descent. (higher apex, steeper descent). We can use the formula 1000 rpm = 7* as difference to descent angle, so it takes 143* rpms to move descent angle by 1* and thats the same for all clubs in the bag. That means if you are a player at LPGA level and your descent (from turf), is 42* you "need" 3 x 143 =429 rpms more spin to get your descent angle to 45*

So, no matter club speed, iron head type or loft, it boils down to stooping power or roll out from spin and descent, and we should then look at descent angle to judge if we have enough spin, NOT the spin value itself, since the angle the ball is falling down that really matters. Just think of a ball we drop down from our hand. It does not spin at all but does not roll anywhere, so its the angle that "makes the need" for spin to stop it in the first place, but all we have to do is look at the angle, then the spin value if we want a steeper or more shallow descent.

So forget that rule of thumb with 1000 Rpms x iron number, its only valid for the #7 and #8 at PGA club speed level, but its not really the spin value thats "valid" but the descent of 50* at this club speed.

As you can all see based on this average number, the average spin change from 1 iron to the next is only 600 rpms for LPGA and 668 rpms for PGA so we are not even close to 1000 and that means the rule of thumb was based on cherry picking after seeing "matching numbers" for only 2 club, and thats useless for a set with 8 irons if the majority is far outside that "rule", so simply forget it.

[BigBlue7]

Ian Fraser said that correlation is just a myth and not something any qualified fitter will look at in a vacuum. Targeted spin number varies as other variables such as ball speed, launch angle, peak height and angle of descent change.

 

[Howard_Jones]

He was right about that, because that rule would make it seems like PGA has 1630 rpms more spin than they should from their #3 iron and thats 1630/3000 = 54% more spin than this crazy rule of thumb try to tell us is "good", but when real life numbers is that much off we must ask the question, is it the map or the terrain thats wrong?