Skytrak overstating backspin rate?

[Laz1881]

I've had my Skytrak for about 6 months. I recently did a clubfitting where the fitter used Flightscope, so I was able to compare Flightscope data vs Skytrak for my current clubs.

The ball speed and swing speed on Skytrak vs Flightscope was very similar, but my Skytrak carry and roll yardages are 5-10 yards shorter. This appears to be due to much higher spin calculated by Skytrak. The spin rates are anywhere from 11% to 30% higher on Skytrak. We used Pro V1 at both club fitting and at home. Also, when I switch to a distance ball at home, higher than normal spin rates continue.

Here is some representative data below:

Club	Device	Carry	Total	Club speed	Ball Speed	Spin (rpm)	Launch Vert
7iron	Flightscope	168	172	93.4	121	7121	19.3
7iron	Skytrak	164	167	95	121	7963	19.3
8iron	Flightscope	157	162	94.5	113.6	6695	20.7
8iron	Skytrak	151	152	91	115	8721	21.2
9iron	Flightscope	140	143	87.2	104.4	8254	24.2
9iron	Skytrak	132	133	86	105	9594	23.8

Have others had similar issues with Skytrak? Could it be related to the golf mat that I'm using (CC Elite Real Feel)? Any help would be appreciated! This has been extremely frustrating for me.

[3on3putt]

1. The difference in mats could certainly play a role. Did you hit any drivers or any shots off a tee during the Flightscope session? Some mats can be spinnier than others. I would bet that if you changed out your CCE mat for something else you would see different spins (higher or lower).

2. Skytrak does not use spin decay, which can exaggerate curvature of the ball. I've always been under the assumption that backspin would also be a little exaggerated as well for the same reason.

3. I'm not super familiar with Flightscope software, but do they give you the option of splitting up the spin between backspin and sidespin like Skytrak does? (The alternative with Skytrak is to have total spin + spin axis). If you're using spin axis on your Skytrak but the Flightscope was splitting them up, you might see less spin on the Flightscope because you might only be looking at one and not both. (Again, I have no idea if Flightscope gives this option.)

4. Don't be too quick to conclude that the Skytrak is over-reading spin vs. the Flightscope under-reading spin. Skytrak is a photometric system and Flightscope is radar. While both types of units have their advantages, indoor spin with radar units is not exactly perfect, especially if there isn't sufficient distance from mat to screen. It's not always perfect with photometric units either (such as the spin decay thing). My point is not to rush to the conclusion that the Flightscope spin is dead-on accurate. Mevo+ (a Flightscope product) has to estimate spin sometimes indoors.

5. As far as roll out yardages go, just ignore it. Two different softwares each with their own formulas for determing roll. Roll out on any launch monitor is honestly useless in my opinion. Angle of descent is a better metric to look at for gauging how much a ball might roll out.

[Morini]

2. Skytrak measures the launch conditions. Lack of spin decay is a ball flight model flaw in Skytrak range, and is unrelated to hardware.
4. Again, lack of spin decay is a software only issue and has nothing to do with spin at launch, nor the fact that Skytrak is photometric.
5. Great point, ignore roll out.

[3on3putt]

Morini --

Thanks for clarifying about spin at launch vs. spin in ball flight model. Makes sense. Related question....

So the lack of spin decay can cause a shot to draw a little more than it actually would have, because that lack of spin decay keeps that draw spin going throughout the flight without letting up.

Let's say I hit a perfectly straight shot with no side spin. Does the backspin keep spinning at the same rate throughout the flight of the ball without letting up and therefore affecting the carry distance?

Just something I've wondered about as whenever the topic of spin decay comes up it's always about shots curving left or right but I've never seen anything about spin decay and backspin and how it relates to carry distance. Just curious.

[Laz1881]

Extremely helpful. Thank you for the feedback.

I didn't hit any drivers on flightscope because I was just getting fitted for new irons. I will look into other mats and see if that is the culprit.

In terms of spin axis, Flightscope summary I have shows 0.5R for 7i, 1.9R for 8i, and 0.5R for 9i. I'm not sure how to interpret that data and compare to Skytrak.

I definitely ignore the roll out. The difference in carry yardages increases as I go down the bag, though. This is why my knee jerk reaction is that Flightscope numbers were more accurate. 164 7i carry is pretty close to real life for me. But I struggle to carry a GW 105 on Skytrak and I can carry it close to 120 on the course.

Again, your response is extremely helpful! Thank you. I'll definitely research alternative mats.

[3on3putt]

Extremely helpful. Thank you for the feedback.

I didn't hit any drivers on flightscope because I was just getting fitted for new irons. I will look into other mats and see if that is the culprit.

In terms of spin axis, Flightscope summary I have shows 0.5R for 7i, 1.9R for 8i, and 0.5R for 9i. I'm not sure how to interpret that data and compare to Skytrak.

I definitely ignore the roll out. The difference in carry yardages increases as I go down the bag, though. This is why my knee jerk reaction is that Flightscope numbers were more accurate. 164 7i carry is pretty close to real life for me. But I struggle to carry a GW 105 on Skytrak and I can carry it close to 120 on the course.

Again, your response is extremely helpful! Thank you. I'll definitely research alternative mats.

It sounds like Flightscope was also using spin axis, so you can eliminate that as the culprit (assuming you are also using axis on the Skytrak).

Give the fitter a call and ask them what kind of mat they use. I know CCE mats have a reputation for being a bit harsh on the joints. I'm not sure what the consensus is as far as spin compared to something like a Fiberbuilt or a TrueStrike. But I think if you're comparing iron spin between two launch monitors, they would have to be hit on the same mat in order to make it a controlled experiment. Otherwise it could be apples to oranges.

[Morini]

I think 3on3putt mentioned it.

• Different mats produce different spin.
• Radar units can struggle indoors, especially if ball does not have metallic sticker

[GungHoGolf]

1. Did you use metallic dots on the balls, and were you careful to position the dot either straight up or straight towards the screen on each shot? If not, FlightScope (which model?) may have been estimating spin. SkyTrak is very, very accurate at measuring total spin rate - I'd for sure trust it indoors over radar if metallic dots were not used.
2. Are you positioning the ball logo towards the SkyTrak? Without it, SkyTrak may not have the visual landmarks it needs for an accurate spin read.
3. As previous posters have mentioned, make sure you're looking at TOTAL spin on each monitor, not total on one, and the backspin component on another.
4. Mats can definitely have an affect, particularly if you were catching some balls slightly heavy without realizing it (high contact on face lowers spin).

Any time we compare SkyTrak vs Mevo+ indoors on the same shots, and are careful to position both the dot and the logo for each, spin rates are within a few % points (very close), and also match up to our TrackMan 4 and EYEXO.

[Laz1881]

Thanks! During clubfitting, we had metallic dots on the golf ball. It's been a few weeks, but I think I was facing them straight up.

On Skytrak, I position the golf ball about an inch behind the red dot with the logo facing the Skytrak unit.

Good point on Total spin vs just backspin. I'm not sure if the Flightscope data was just looking at backspin. Hypothetically, if the spin numbers were the same and ball speed and launch angle were about the same, what would lead to different carry yardages on Flightscope vs SKytrak? And the carry differences increasing as you go from 7i (4yd gap) to 9i (8yd gap).

[GungHoGolf]

The carry differences are due to the difference in spin rate. Spin makes a huge difference in carry distance.

[Morini]

Gunghogolf, I think laz1881 meant that if there wasn't any spin discrepancy after using apples to apples total spin, why was there a carry difference? Ball flight models are not identical, but very similar (except for the Skytrak over reporting ball curvature).