Use TrackMan Numbers to Quickly PinPoint the Strike
Back in September at The Belfry whilst attending a TrackMan day Tom Davis of TaylorMade showed us this image of Rory McIlroy’s TrackMan data from a shot he had hit with driver….. As you can see Rory has tickled it out there 356 yards. Tom asked the question “How has Rory hit it so far?”
A few people said Club Speed. But Tom said look past the club speed what else has he done so well to get that ball out there 356 yards? One of the pros in the room put his hand up and said he must of struck it slightly high and out the toe in the clubs “HotSpot”. He argued this would reduce the spin and increase the launch and could explain the 356 yard bomb. Most of the room agreed.
This isn’t true though as Rory actually hit this drive out the heel…
Yes you read that correct, Rory hit it over 350 Yards slightly out of the neck! Hopefully by the end of the article you will be able to understand how we can tell Rory did in fact hit this shot out the heel, granted only slightly, by only looking at the TrackMan numbers. And the next time you have a TrackMan in front of you, you have a better understanding where the strike has come from.
“Face to Path” and “Spin Axis” Reveal All
To predict the strike in the simplest way we only need to look at two TrackMan parameters “Face to Path” and “Spin Axis”. If you do not know much about these two parameters now is the time to stop reading this and log onto the TrackMan University site and read or watch a few “Face to Path” and “Spin Axis” explanations.
*For the sake of this article any time I say centred strike presume the clubs centre of gravity is in the centre of the club head.
**Its important to note that this is article is specifically for shots hit with a Driver. I will explain why iron shots are different at the end.
Straight Shot from a Centred Strike
If your “Face to Path” comes in Zero and you strike the ball in the centre of the club face then we will also see a “Spin Axis” of zero. This golf ball will not have any curvature, so if it starts down the target line like the shot below, it will finish on the target line.
What a Centred Strike Will look like in Numbers
Spotting a centred strike is very simple. For each degree of “Face to Path” difference we should see a spin axis of 6.
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So now we can use this method to judge this shot. It has a “Face to Path” of +1 and a “Spin Axis” of +6.2 so we know this shot was a centred strike.
Numbers from an Off Centred Strike
Spotting an off centred strike is equally as simple. For each dimple the ball is struck out of the heel or toe we should see a spin axis of 6.
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So we can quickly see that this shot below has a “Face to Path” of 0.0 but a “Spin Axis” of -1.8 so the ball must have been struck out of the toe. This was only a very fractional toe strike.
With this shot below you can see the “Face to Path” is only -1.7 so the “Spin Axis” should be around -10. So to get a spin axis of -35 we know he must have hit the ball a long way out of the toe. Around 4 dimples out the toe to be precise.
So Back to Rory’s Drive
Now you may feel ready to reassess Rory’s drive for your self. As we can see his Face to Path is -1.4 degrees. So we know if he caught this out the middle of the club face his Spin Axis should be around -8. The fact that his spin axis is actually +3 shows us it was a heel contact.
A Heel contact of about 2 dimples.
Ignorance Can Be Bliss
Using this newfound knowledge it can be easy to get bogged down over analysing the strike of every shot. For good shots like these below it doesn’t really matter whether the shots were fractionally toe or heel strikes. They are all off centre strikes but they have all gone straight and were good shots.
The Best Time to Check Strike Using this Method
I use this method when ever I see a lot of curvature in the shots. Whether it’s good shots curving onto the target or bad shots curving away from the target. This allows me to gauge whether the curve was caused by an off centre strike or from the path and face combination.
Here is a perfect example.
We have a shot that has excessive amount of curve to the right. A bog standard slice. It could be easy to presume that for a shot like this the face must be very open. A Face to Path of +6 perhaps. To fix this shot you may check for weak club face from grip or wrist positions or poor release patterns.
But with a quick check of strike location using Face to Path and Spin axis we can see the Face to Path was -1.6 degrees! The face is actually shut to the path for this shot, Spin Axis should be -10 if this shot were a centre strike. With the Spin Axis at +10.6 we know he has hit this considerably out of the heel of the club.
Can You Use This for Iron Shots as Well?
Yes, you can use this technique to predict strike with iron shots too. But it is not the same formula. This is due to the effect that Spin loft has on D-Plane. Below you can see this change with different clubs.
***This part of the article gets a little more mathematical now as we start to change the Spin Loft and resulting D-Plane.
Spin Axis from D-Plane (1 Degree Face-to-Path)
| Spin Loft | Spin Axis |
| 10 deg (dr-3w) | 5,7 deg |
| 20 deg (3i-6i) | 2,9 deg |
| 30 deg (6i-9i) | 2,0 deg |
| 40 deg (9i-Wdg) | 1,5 deg |
As you can see with 10 degrees of spin loft (Driver and 3 Wood) each degree of face to path difference you will get a spin axis of 5.7 degrees (or 6 degree as I have rounded up to ? ). As spin loft increases through you irons the amount of spin axis created changes. This applies difference also applies to Spin Axis through off centre strike. As gear effect is greater with a driver than it is with a 7 iron. This can be seen below.
Off Centre Impact – Ger Effect – Spin Axis Tilt
| 1/2 Inch | 1/8 Inch | |
| Driver | 20 deg | 5 deg |
| 6 Iron | 7 deg | 2 deg |
Using this formula, an off centre strike of 1/8 of an inch (3.175 millimetres) will change the spin axis by 5. The average size of a dimple of a Pro V1 golf ball is 4 millimetres, using the information above 4 millimetres will change the spin axis by 6 with a driver. So for each dimple off centre the spin axis will change by 6 as seen in the above tables.
Given that Trackman can estimate the strike using the above calculations, why isn’t this then automated for every shot? (again, understanding that this would be a calculated value based on the assumption that geometric centre of the club = club head’s centre of gravity)
this is a great question….would love to hear an official reply…competitor such as foresight shows impact location of club face…
Not official (yet), but it appears Trackman will soon be releasing an upgrade that displays where on the face the ball was struck. https://twitter.com/TrackManGolf/status/954312222746071042
This is an interesting article….thank you!
PS….there are 2 types of “weather” and “whether”…..spell check got you twice!☺️
Good catch! It should be fixed now ;-)
Great article;thank you!
Awesome article and calculation… But 2 questions that come to my mind:
1) It also says in the chapter ‘Ignorance is bliss’. So does this mean the math/calculation won’t always work as it is (by back-calculating 6 degree on Spin Axis left or right depending on Face to Path?). Because I’ve seen some cases where just by looking at the Face to Path and Spin Axis it should’ve been either a heel or toe strike, but in fact the ball was struck near the middle.
2) So what does vertical impact have to do with this? I’ve tested this with my friend, and it seemed like low heel strikes tend to give out some different Face to Path and Spin Axis calculation. Does High or Low impact point matter about toe/heel strikes, other than giving you more/less spin rates & higher/lower launch angles?
Hi Leo, good couple of questions. Hope this clears up;
1) by ignorance is bliss, what I mean is for the majority of shots I watch on the trackman I don’t do this calculation. Every straight or flushed shot on the range if you wanted to look at strike location it will always be slightly toe or her contact. But 1/4 or 1/2 a dimple here of there I don’t care about. So therefore “ignorance is bliss”. Don’t over evaluate shots.
In real world you will always get some numbers that don’t fit the model. The most likely reason for this is how COG can change from club to club. So therefore it might look like you struck the shot out the neck if using Dr Scholes but if the COG is out for that specific club then the numbers may not be what you expect to see.
2) DPlane answers your second question. When know that dynamic loft has an effect of how much spin axis is created per degree of face to path difference as the end of my article explains. So therefor a shot struck out the bottom or top of the club has different dynamic lofts so low out the heel and high out the heel will have different spin axis calculations. I don’t know the calculations for the vertical gear effect so I’m afraid that’s about as good as I can do.
Thanks a lot. This helps explaining to understand. I guess it is not as easy I thought, and that it is not a simple calculation as you mention in the post, due to each club being all different.
Then would it be safe to say that, if it was a straight shot or a shot that started from the left or right but ended back to the same horizon as when it first started, would be a near centered strike regardless of the actual FTP and Spin Axis numbers?
In other words, your calculation will be more prevalent shots that had a lot of curvature?
Thanks for the explanation.
So if you can help me with my last 2 conclusions:
1) would it be safe to say that as long as the ball landed on the same vertical line as when it first started (regardless of fade or draw curve), those shots should mostly be near centered strike?
2) in other words, your calculation will mostly be prevalent on shots that had a lot of curvature to see if it had a gear effect or where the ball hit on the club face?
Thanks. It looks like the simple calculation is not all there is, since there are varieties of club types.
Sorry I double posted thinking my first post didn’t go through.
One other question: you were referring to loft for each club giving out different spin axis degrees (ie loft 10 = 5.7 degree). Are you referring to “Spin Loft” or “Dynamic Loft”?
Thanks.