Clubhead & Ball Speeds Are Correct...but Yardages Are Hugely Inflated...

[Rogala]

Please see the attached raw data with a 7-iron off of a short tee for 10 "good shots". I used this to compile a Skytrak comparison for hitting off of my mat vs. hitting off of a short tee.

I have also attached an Excel spreadsheet showing data from both SkyTrak (camera based) and Swing Caddie (doppler radar based) for 10 shots I hit yesterday off of a mat, versus 10 new shots off of a short tee today. The systems were used simultaneously to get this data on the exact same swings (10 yesterday and 10 today).

Findings:

1) There was basically no difference in backspin number off my gel-insert mat vs. a tee. SkyTrak showed an average backspin of about 4,000 RPM for both a mat and a short tee. Swing Caddie showed an average backspin of about 6.300 for both a mat and a short tee. Looks like Gel-insert mat really are a damn good way to go.

2) I did lose ball speed in hitting off the mat vs. the tee. Both the Swing Caddie and SkyTrak showed a 6 mph loss of ball speed...which resulted in a 4 yard loss of carry per both systems.

3) I marked a few excel boxes in RED to show major differences between the SkyTrak numbers and the Swing Caddie numbers. Backspin RPMs stand out, as do (predicatly per the RPM differences) the shot apex numbers....which are 30+ feet lower per SkyTrak. Am I really hitting it 30 feet lower than I think I do based on my IRL experiecne ??

4) One other oddity is that SkyTrak reported a 4.1 mph loss of clubhead speen when going from a tee to a mat. Swing Caddie reports a 2.4 mph loss of clubhead speed for the same transition. Am I hitting it a little fat off the mat ??

So if it is NOT my mat causing the lowered RPM numbers, then what is the issue ?? Something in the device set-up ??

Also attached is a photo of my "short tee" set up.

P.S. As an odd aside, I kind of feel like the SkyTrak yardage numbers (which are a bit lower overall) are actually closer to my IRL despite the backspin numbers appearing to be way too low. How that is possible, I have no idea....but this RPM issue is a fascinating one.

[Rogala]

Do you have any other mats lying around that you could experiment by hitting off of? Different mats produce different spins so I wonder if your mat might be the common denominator here.

I do have a different mat I could try...and will probably do so later this evening. In the mean time, please see my next data set which was taken off of a short tee. It does NOT seem to be a mat issue based on that data. Posting it shortly.

[RAH5]

I took the advice above and deep cleaned my clubs/grooves/etc.

Spin went up significantly and carry down accordingly.

Still generally in the low 5’s, probably a bit low, but I’m attributing it to the mat.

Overall I’m very happy with it. I’m loving the feedback and the range session numbers.

Thanks all!

[3on3putt]

Do you have any other mats lying around that you could experiment by hitting off of? Different mats produce different spins so I wonder if your mat might be the common denominator here.

[Rogala]

The distances look reasonable based on my IRL play...but the spin rate still seems low to me..mat or no mat...especially based on other club and ball fitting sessions I have done. See some other posts by me regarding 7-iron RPM rate data in these sessions from 2012 onward.

Also see several other posts citing threads started by users on this forum wondering about low spin reproting by SkyTrak over the years.

Reports of "lower than expected backspin" sure seem to be a real thing. If it can be corrected with set up tweaks, I am all ears and want to get the unint dialed in, as best I can.

Again, thanks for patience with a SkyTrak newbie.

[Rogala]

Here is a search on some threads dealing with low spin and Skytrak.


https://www.google.com/search?q=skyt...obile&ie=UTF-8

Thank you !!! The below thread in particular dealt with low 7-iron spin rates in the same exact range as I am seeing...very helpful to know that others have experienced this.

https://golfsimulatorforum.com/forum...low-spin-rates


This comment from a different "low spin" thread on this forum was also what I am seeing:

04-12-2018, 03:52 PM
Originally posted by clark55810 View Post
I am seeing exactly the same thing...

I have had my ST since last June and didn't really follow spin numbers since I was looking mainly at carry distance, which seems to be correct.

With the new optimization measures, it was very obvious that my spin on my 8-iron is about 1/2 of what the standard it. Kind of weird that my other numbers look good (ball speed, carry, etc) which doesn't correlate.

Same here. If the carry and direction is accurate, I'm some what okay with that. But I still would like to know the true (or close) backspin.

If I need to make changes in my SkyTrak set up to get accurate spin numbers, then so be it...just want to figure out how to do it...or have someone else enlighten me.

All these threads make me realize that this has been a question that many other people have been raising (now and again) for years now....

[Rogala]

;-) LOL...I figure I would wait for the other "Real Thing"...

[Rogala]

Backspin has a significant effect on carry distance. You can check how it affects it here

https://flightscope.com/products/trajectory-optimizer/

The type of mattress has a great influence on the backspin. It is enough that the contact of the club head is earlier (even minimal) with the mattress than with the ball and the backspin drops dramatically.

OK, that was a FANTASTIC little link.

I plugged in some numbers from various club and ball fitting sessions over the last 8 years (all done indoors using mats) and all the readings from the optimizer page were right on the money with the data I was presented in those sessions.

I then kept all the other variables the same, but lowered the 7-iron backspin RPM rates about 2,000 RPMs (from the 6K range to the 4K range) to match what I am seeing on my latest SkyTrak numbers off of a mat from yesterday, and BINGO...the extra length which SkyTrak is reporting (what I termed the "inflated yardages") are right there.

This strongly suggests to me that we are indeed talking about a backspin reporting issue...either due to my set-up, or some other problem.

I made sure to have the logo on the ball pointing at the camera yesterday...but I will check out some other set-up tips from Gungho and others immediately.

[Rogala]

I just got done playing tgc and after the round I hit a few 7 irons on the skytrak range to see what kind of spin numbers I would get. Like I said previously, I generally don't pay much attention to spin unless I'm hitting driver. I hit 5 balls and they were all between 6100 and 6400. That was with a taylormade tour response ball and titleist AP2 iron off a rawhide mat.

Interesting...

Last night, I went back and pulled all the data I had from every club and ball fitting session I have done since 2012. Trackman or other radar-based systems were used for most of these (maybe 3/4 of them?) and the other session were done using either camera-based or combo-based (camera + radar) launch monitor systems. All were done at professional facilities, including two "high-end" facilities known for catering to elite golfers.

All of these sessions I went over were done indoors hitting off of a mat, and my 7-iron back "average backspin rates" for every one of these was reported to be between 5,800 to 6,300 RPMs. With the 5000RPM band being due to some combination of different golf balls, different mats or my swing being different from one session to the next. My point is the range is very consistent for indoor sessions when hitting off of mats. (Note: I also have some trackman data from one other session where I hitting off driving range grass during a PXG fitting...and "yes" my spin rates were higher that day.)

Note: That range of 5,800-6,300 RPMs is, overall, probably a little lower than many other players might have with their 7-irons. It has been my belief that I have always generated a bit less back spin on my shorter irons than what might be expected of a low handicapper. I say this based on my IRL perfomance with my short irons...meaning I was never known for spinning wedge shots backwards, although I can usually stop my wedge shots from good lies after one or two hops....my slightly lower than expected backspin rates are likely due to some idiosyncracy of the way I deliver the clubhead and my clubhead speed itself.

All that being said, the SkyTrak numbers from a mat yesterday are still way below these figures, so it looks like something is still off on my SkyTrak set-up...mat or no mat. As I wrote, I am going to try a short tee today for comparison....but, again, all the above figures from 2012 onward were off mats.

[Mirek_62]

You can use a Coke cap as a short tee. 😉

[Rogala]

So, I didn't hit off of a short tee (as was suggested) because I could not...for the simple reason that I didn't have one yesterday and couldn;t get one because my club was closed for New year's Day. I was able to go over to my club today and get one, and I will hit some balls later.

I will try it off the tee and then report back on what the "spin loss" is with my exact mat.

Any thoughts about why the 1/2" of extra height casued by the feet on the metal case was causing the spin numbers to be 1,500 to 2,000 RPMs too low versus the RPM numbers with the feet removed ?? Just trying to understand SkyTrak a bit better.

[Morini]

You would pay attention if you went below 5K an you'd have trouble stopping the ball. But I get your point, you don't pay attention because you don't need to. Anything over 6 K is great off a mat. My DIY DA is creating more spin than I expected. Both my son and I are averaging just below 7K. Basically full fairway spin for our ball speeds.

[3on3putt]

I just got done playing tgc and after the round I hit a few 7 irons on the skytrak range to see what kind of spin numbers I would get. Like I said previously, I generally don't pay much attention to spin unless I'm hitting driver. I hit 5 balls and they were all between 6100 and 6400. That was with a taylormade tour response ball and titleist AP2 iron off a rawhide mat.

[Fhacker]

Those numbers look pretty good for an amateur. Not sure what else I can say

[Morini]

Again, low spin off mat. Hit off short tee.