TheStack System Club Speed Trainer


Available on back-order

We are now accepting PRE-ORDERS for The Stack System. Expected delivery is October 2022.

TheStack….Finally, a complete system for biohacking your clubhead speed!

Precision Hardware: 5 CNC milled Stack weights combine with a custom engineered shaft & hardware to create 30 unique combinations for unlocking dynamic variable inertia speed training.

Dynamic, App Based Training: Programming directly from golf’s leading biomechanist, Dr Sasho Mackenzie are now available to you through an innovative App that acts as your personal trainer.  Powered by A.I., the App records speeds, guides workouts, and gives custom metrics to keep you motivated.

Tracking Speed: You’ll need a speed tracking device to get started. TheStack prefer the PRGR but TheStack is compatible with other options.  Read more about compatible speed tracking device options in the ‘Radar Devices and Integration‘ section.



The Stack System provides dynamic programming directly from golf’s leading biomechanist. Speed training secrets previously reserved for Tour players, now available to you.

Dr. Sasho MacKenzie, Co-Founder

Golf’s foremost biomechanist, Dr. Sasho MacKenzie is the research practitioner behind the world’s top golf coaches – his work and theories have driven a scientific, evidence-based revolution in golf instruction and movement training.

Sasho’s area of expertise is the training and biomechanics of speed generation. The Stack System allows Sasho to share his research findings and training wisdom directly with you, using the same tools, techniques, and nuances that he uses to speed train Tour players he has consulted.

Variable inertia speed training is the most efficient way to increase speed.

TheStack Hardware

  • 5 milled Stack weights enable 30 weight combinations between 0g and 300g
  • Dual-purpose weight case / phone stand
  • Highly engineered training club – Adult 105cm (41.5″)

TheStack App Training

  • Dynamic speed training formulated by Dr. Sasho MacKenzie
  • Guided workout timer for reps, sets, and rest intervals
  • Custom speed metrics to track your gains
  • Hands-free data entry using voice entry technology
  • Includes Single User Licence – Enables training and tracking for up to five local users under one login.
  • 2-year Single User Licence, accessible on iOS.

Access TheStack App from the App Store when your order arrives.  iOs only (13.0 or later)

app store link

* Applies to Single User Licence only



Matt Fitzpatrick - US Open speed gains!

Matt Fitzpatrick - US Open speed gains!

Coverage on TheStack begins at 4.30pm

Dynamic Training

Dynamic Training

Programs & Training

TheStack is a personal swing-speed trainer for golfers.

Initially, each golfer is piloted through a series of swing speed tests to generate a force-velocity profile of their current swing. Qualitative data is gathered on perceived strengths and weaknesses related to generating clubhead speed.

Based on individual comprehensive baseline data, TheStack App’s artificial intelligence (A.I.) algorithms provide a list of customised program options. The program list is rank ordered starting with the program that has the greatest likelihood of increasing clubhead speed over a 6 to 10 week period, which equates 18 to 24 training sessions.

TheStack App

TheStack App

TheStack App provides customised variable inertia speed training – the most efficient way to increase your clubhead speed. The algorithms that power the dynamic programming come from years of research by leading sport scientist, Dr. Sasho MacKenzie.

Here is how it works…

Dynamic Training Programs

TheStack App functions as your own personal trainer, guiding you through scheduled workouts while tracking Stack weight, rest, recovery, and performance gains. This information allows future workouts to be adjusted behind the scenes, so your training is optimized to maximise clubhead speed gains.

Baseline Session

Similar to working with a personal trainer, you are guided through a detailed intake session. Qualitative data is gathered on perceived strengths and weakness related to generating clubhead speed. You’ll be coached through a series of swing speed tests to generate a force-velocity profile of your current swing. This data informs A.I. algorithms which create custom programming options. 


Following the Baseline Session, TheStack App provides a list of customized programming options. The list is prioritized specifically for you by greatest likelihood of increasing clubhead speed over a 6 to 10 week period (18 to 24 training sessions).


During each training Session, TheStack App coaches you through each swing – seamlessly guiding stack weight configuration, swing intent and rest for each rep and set.

Hands-Free Data Collection

Using TheStack System’s voice entry technology, enjoy hands-free data collection during training sessions, by simply dictating your speed readings into the App. The hands-free data capture feature even works when wearing AirPods or earbuds. If you are training with a coach or friend, numbers can be keyed.

Workout Summaries

Detailed post-workout data review enables you to verify and, if needed, make any changes to speed data before syncing to the cloud.

Tracking and Sharing Metrics

TheStack App tracks key performance metrics such as Stack Speed, Distance Potential, Clubhead Speed and Grit Score. Easily share your progress and gains to your favorite social media platform.

Progress Checks

After completing a training program, TheStack App re-assesses your gains with a Progress Check, from there reformulating your next program. Data captured along the way improves the intelligence of TheStack algorithms through A.I. techniques.

Cloud Storage

Training data is stored securely in the cloud.  Whether you get a new phone or want to login from another device for your next training session, everything works seamlessly.

Radar Devices and Integration

Radar Devices and Integration

Tracking speed is not as easy as it sounds.  At TheStack System, we analyse nearly all radar devices that track training swings and TheStack App factors out any bias, or systematic error, in speed measurements that are associated with our hardware design.  What does this mean to you?  If your radar measures with a bias, our smart algorithms adjust for it and accurately calculate your eSpeed and Distance Potential regardless of which device you are using.

Tested Devices

Brand Description
PRGR Black Pocket, Red Pocket
Sports Sensors Swing Speed Radar®
FlightScope X2, X2 Elite, X3, Xi Tour
Garmin G80
Swing Caddie SC200 PLUS
Yupiteru GST-5, GST-7 BLE

PRGR TheStack preferred

The PRGR is great for training with TheStack.  It is small and packs into your golf bag easily, and gives the added benefit of being a great device to bring onto the golf course to measure ball speed while playing.


Read more about the PRGR and purchase via Golf Swing Systems HERE

Sports Sensors – The Swing Speed Radar

The Swing Speed Radar® by Sports Sensors is a time-tested and reliable radar that measures club-head speed only.  If you already have a Sports Sensors radar, you’re all set to start with TheStack.


Swing Speed Radar blue

Read more about the The Swing Speed Radar and purchase via Golf Swing Systems HERE

Swing Caddie – SC200 Plus

The Swing Caddie SC200 Plus is a portable launch monitor that measures both swing speed and ball speed.  Swing Caddie recently added Swing Speed Mode to enable training with TheStack.

Learn more about the The Swing Caddie SC200 Plus and purchase via Golf Swing Systems HERE













I have TheStack hardware, how do I get started training?

  • From The App Store, download TheStack App (iOS) and login with your Apple ID.
  • Enter the Serial Number found on the threaded stem of your Stack hardware.

Is a speed radar device required for training?

Yes, measuring your speed and dynamically adjusting your Stack Weights during your training is fundamental to The Stack System.

Where do I find my serial number?

Your serial number is located on the threaded stem of your Stack hardware.

I’m an Android user, what are my options?

For now, TheStack App is only available on iOS.  You can use TheStack App on an iPad (iPad Pro, iPad 5th gen or newer) – the large display makes for a great training experience.  Check back with us for future availability on other platforms.

I lost a Stack weight, how do I get a replacement?

Please e-mail We’ll work out details with you to send a replacement.

Can I hit a golf ball or smash bag with my Stack hardware? 

No!  TheStack hardware is engineered and tested for non-impact training swings only.  It is not intended for ground impact, ball impact, or use with a smash bag.

I got a new phone, what happens to my training data?

New phone?  No problem!  Your training data and profile is store securely in the the cloud.  You data is then stored with your login, not your device.  Simply log back into TheStack App (iOS) from your new device and continue your training.


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