Ball speed vs Club speed

[Jason R]

I’m sure this has probably been raised before however...
Been hitting wedges on my skytrak and wondered if these numbers are correct, told my club pro that my club speed on skytrak regularly reads higher than my ball speed with my gap wedge, he maintains that it’s impossible for the ball to bounce off the club face at a slower speed than the club speed. Not doubting him in anyway though I did explain the analogy of a table tennis bat chopping at a table tennis ball with backspin and I’ve always thought that the bat speed seemed way faster than the high spinning table tennis ball bounces off !
Im probably wrong so if anybody could enlighten me would be chuffed. Also my driver club speed on Skytrak never goes above 95mph which is baffling as my wedges regularly read in the 90mph zone ? Is my machine faulty ?

[dws90]

He's correct, it's impossible for ball speed to be lower than club speed.

[wbond]

Do not even look at club speed. It's not measured.

[Clevited]

Until Skytrak revamps their method for calculating swing speed like they are planning to, I created an excel tool to help me determine club speed based off Skytrak's measured values. It requires a well struck shot (center hit or close to). Myself and others have found it quite accurate. I checked it against a bunch of trackman sessions for pro's as well as Rick Shiels club testing data from his GC2/HMT and GCQ and it almost always is within 1 to 2 mph on the swing speed.

As an example, I calculate a roughly 72 mph club speed assuming you are hitting a GW which is 35.5 i nches long. That is a smash factor of 1.2. Tells me you have a very nice decending strike. Spin numbers are very nice.

EDIT: I didn't need to assume a length to calculate that 72 mph. Club length is only needed in the calculator if you want to estimate swing speeds of your other clubs. Just thought I would clarify.

https://golfsimulatorforum.com/forum...eed-calculator

[shimonko]

A bunker shot can have the ball speed less than the club speed (similar to table tennis), as can a severely topped shot. Other shots though - the speeds would be the same if the ball adhered to the face, so for the ball to bounce off it must be traveling faster.

Here's a Trackman analysis of a bunker shot: https://blog.trackmangolf.com/bunker...he-trackman-4/

[Ronsc1985]

It depends on how you are measuring ball speed. If ball speed and clubhead speed are relative to the ground then the ball speed can certainly by lower then the clubhead speed. A simple example would be a club with a 90 degree loft. The ball relative to the ground would have no speed at all while the clubhead would.

In general the more lofted the club the less the ball speed relative to the ground.

[skytrakali]

Warning! Nerdy math alert!

Here's how I think that Skytrak do club speed and smash factor:

(1) Smash factor = ball speed/clubhead speed. That's all. So if you can estimate the club speed you get smash factor
(2) Skytrak ACTUALLY MEASURES 5 things: ball speed, ball side spin, ball back spin, launch angle and side angle. It doesn't measure the club head at all and doesn't claim to. It also knows what club you're hitting (assuming you tell it)
(3) So how can we estimate CH speed from ball data only?
(4) Idea: use another (much much more expensive) launch monitor that measures everything (eg GC Quad). Then use the 5 Skytrak-measured parameters to make the best prediction ("best fit") of the actual clubhead speed
(5) This will often be right - but will also be wrong quite often as well.
(6) To prove this: take a Skytrak data session and do a multivariate regression on the 5 measured parameters to back out the coefficients (call them c1 - c5) for a linear fit
(7) Then we have CH speed = c1*(ball speed) + c2*(side spin) + c3*(back spin) + c4*(launch angle) + c5*(side angle)
(8) The c1-c5 are different for each club

I've done this and it works - I get the reported CH speed from the ball speed parameters when I do the regression

[Kris]

For #7, I may be missing the obvious, so forgive me. But how could that be used to get clubhead speed, if ball speed should always be higher than clubhead speed? The fact "c1" is ballspeed and then you're adding to that number, rather than subtracting from it?

[skytrakali]

One other thing: shimonko is right - pics of bunker shots show that for almost all good bunker shots the club is going faster than the ball. But in a bunker shot the club does not touch the ball. The ball is propelled out of the bunker by a travelling wave in the sand. But waves in media such as sand are supersonic (i.e. supercritical) as the wave speed is the sand is very high. Smash factor is only really defined properly if the club actually hits the ball.

[Ronsc1985]

Warning! Nerdy math alert!

Here's how I think that Skytrak do club speed and smash factor:

(1) Smash factor = ball speed/clubhead speed. That's all. So if you can estimate the club speed you get smash factor
(2) Skytrak ACTUALLY MEASURES 5 things: ball speed, ball side spin, ball back spin, launch angle and side angle. It doesn't measure the club head at all and doesn't claim to. It also knows what club you're hitting (assuming you tell it)
(3) So how can we estimate CH speed from ball data only?
(4) Idea: use another (much much more expensive) launch monitor that measures everything (eg GC Quad). Then use the 5 Skytrak-measured parameters to make the best prediction ("best fit") of the actual clubhead speed
(5) This will often be right - but will also be wrong quite often as well.
(6) To prove this: take a Skytrak data session and do a multivariate regression on the 5 measured parameters to back out the coefficients (call them c1 - c5) for a linear fit
(7) Then we have CH speed = c1*(ball speed) + c2*(side spin) + c3*(back spin) + c4*(launch angle) + c5*(side angle)
(8) The c1-c5 are different for each club

I've done this and it works - I get the reported CH speed from the ball speed parameters when I do the regression

Unless the data points, hit to hit, are fairly close to each other, simple linear regressions work poorly with larger numbers of variables. You could do a lot better with higher order equations. That said at the end of the day it is a heuristic method which will fail miserably when the input parameters are outside of the envelope of the input variables used to find the coefficients.

Aside from all that if you must know the clubhead speed cough up about 100 bucks and get one of the cheap radar club speed devices.and use it in conjunction with the skytrak.

I've never understood the fascination for clubhead speed when you have actual ball launch conditions. Once the ball leaves the clubface it doesn't care at all what the clubhead speed was. I suspect it's a hangover from days gone by, prior to the arrival of accurate launch monitors, when only head speed was available.

[Clevited]

Clubhead speed is obviously not as important as ball speed but I would argue that you can learn an aweful lot from club speed and it is therefore very important. You can learn if technique changes for instance are improving your swing speed and therefore potential ball speed even if you don't strike the ball well (which might only require a tweak elsewhere in ones swing technique to correct) . If all one sees is ball speed, they can't necessarily infer if it was a faster swing, a better strike or a more delofted strike.

I for one feel that many average joes are much much faster swingers than they think, they just don't ever try to up their ceiling, put the time in to improve technique speed wise, or just don't realize they dump speed early and are chicken winging to keep club square.

I myself have legitimately improved my swing speed by near 20 mph over past few years just by changing technique and hitting lots of balls. Had 120+ in me the whole time.

[shimonko]

My first thought as well - highly unlikely linear.

[skytrakali]

Yep agree 100% with Ronsc1985. Spend not very much more and get accurate CH speed data. CH speed is not the crucial factor. My experience though is that Skytrak is very good at giving accurate ball launch data and that's the key thing for me.

I lurv my Skytrak and the ball data is what really helps me to improve my golf.................

[Ronsc1985]

Clubhead speed is obviously not as import as ball speed but I would argue that you can learn an aweful lot from club speed and it is therefore very important. You can learn if technique changes for instance are improving your swing speed and therefore potential ball speed even if you don't strike the ball well (which might only require a tweak elsewhere in ones swing technique to correct) . If all one sees is ball speed, they can't necessarily infer if it was a faster swing, a better strike or a more delofted strike.

I for one feel that many average joes are much much faster swingers than they think, they just don't ever try to up their ceiling, put the time in to improve technique speed wise, or just don't realize they dump speed early and are chicken winging to keep club square.

I myself have legitimately improved my swing speed by near 20 mph over past few years just by changing technique and hitting lots of balls. Had 120+ in me the whole time.

Some people make that argument. Seems to me any beneficial change you made would have been reflected in your ball speed and other launch parameters. If it isn't then the change you made is useless. You can increase clubhead speed by several methods but if you can't hit the middle of the clubface it's all wasted effort. There are several free ball ballistics programs that you can use to figure out what your optimum launch conditions are.

[Clevited]

I would agree with most of what you say but I know a lot of people disregard a swing change that gives them more speed just because they hit the ball more poorly. That swing change isn't necessarily wrong, it just requires perhaps another tweak to correct that issue. Problem is, many make the change, hit less flush and disregard it as a bad change. Have to commit to the change if you want to learn something new.

If you were to swing a full swing and found out you were dumping 20 mph a foot behind the ball, wouldn't knowing that be something that would drive you to make some major change? If i remember correctly, Rory Mcilroy discovered something like that in his swing.

I had a few accelerometer based devices and they told me I was dumping speed way early but I had a lot of wasted potential. I was around 105 tops club speed, but now I am now topping out at 125 when I go after one. I learned to swing more efficiently, now I am working to hit more squarely.

[Jason R]

Thanks for all the nuggets of info, so I'm assuming everyody has the same readings therefore my Skytrak is not faulty ?

[Kris]

I've had the SkyTrak since September; now and then the clubhead speed will read higher than ballspeed, but it's rare that it happens. So I would say now and then the device will get some things wrong, but I have high confidence in the numbers it reports generally speaking.

Also, I'd suggest that if SkyTrak is computing the clubhead speed using other variables it's tracking; a really bad shot could mess up the numbers. For instance, when the clubhead speed seems way too high compared to ball speed; it's normally when I hit a shank, off the hosel or some other kind of bad shot.

My rule of thumb with the device is the better you hit the shot; the more precise it will read it. The worse your shot and the numbers are less reliable. And personally, when I hit a real bad shot, I could care less what the numbers are; I know they suck; I just focus on hitting the next shot good and reviewing those numbers, which are more accurate imo.

[Clevited]

Seems to me your Skytrak is working just fine Just ignore the swing speed numbers it spits out, sometimes they are accurate sometimes they aren't. Id recommend a swing caddie to measure swing speed and smash factor, mine is pretty darn close to right on.

[Martin Hastie]

Exactly what I do as well. Tiny bit on the high side as it measures toe of club which is a tad quicker than middle clubface. But pretty good really

[Clevited]

I just got mine, and I am pretty happy with it so far. For my swing it seems to read a tad slower than Trackman, but I haven't yet confirmed that.