Wednesday, January 27, 2010

Endless Belt, True or False?

Endless Belt (2-K) is a concept of Homer Kelley’s that he discussed in his book ‘The Golfing Machine.’ It’s a concept that many physicists like to claim that ‘Homer got it wrong’, but also a concept that TGM followers still praise.

This blog post will give my thoughts on the subject.

I won’t bog you down with the ‘belt sander’ concept of Endless belt too much, but here’s a diagram showing what Homer Kelley had envisioned the hands and the clubs moving like in the downswing.

There are essentially 2 parts to Endless Belt.

1. The hands are supposed to stay at a constant speed on the downswing. The clubhead will actually accelerate on the downswing, especially as it goes around the ‘wheels in the pulley.’

2. The smaller the golfer’s ‘pulley’, the slower their hand speed can be to generate clubhead speed. The bigger the golfer’s ‘pulley’, the faster their hand speed will have to be faster to generate more clubhead speed.

What’s this mean?

The earlier in the downswing the golfer releases the clubhead, like a ‘full sweep release’ that means their ‘pulley’ is bigger. The later in the downswing the golfer releases the clubhead, like a ‘snap release’ that means their ‘pulley’ is smaller.

Let’s take this a little further.

When I think of a ‘snap release’ with a ‘small pulley’ I think Sergio Garcia is a great example.

When I think of a ‘full sweep release’ with a ‘large pulley’, I will use Brian Manzella student Lindsey Gahm.

Or to put it in a clearer, historical reference, let’s say Ben Hogan (snap release – small pulley) and Tom Watson (full sweep release – large pulley).

Let’s say both Hogan and Watson are hitting the same exact driver and both reach a clubhead speed of 115 mph. In order for Watson, with his full sweep release and large pulley to reach the same clubhead speed as Hogan with his snap release and small pulley, Watson’s hand speed HAS to be much faster than Hogan’s speed.

That’s the Endless Belt concept in about as clear of a nutshell as I can put it.

But back to the critics vs. the followers.

Where I believe the critics are right about their dislikes of Endless Belt is in part 1, the hands staying at a constant speed on the downswing while the clubhead accelerates.

I concur that this is incorrect.

The hands actually slow down and slow down dramatically in the downswing, right when the hands release the clubhead. Sports Science had a great video showing this with Jason Zuback’s swing. But this is the only video I could find. There’s another Sports Science episode where they show *exactly* when Zuback’s hands slow down, this video isn’t it...but it’s close.

For further proof, I would suggest going to Dr. Robert Grober’s lecture on the subject. Go to Click on the SG Classroom tab. Go to Dr. Grober’s Lectures and click on ‘Golf and Physics.’ At about the 40 minute mark Dr. Grober shows some diagrams of golfers of all handicaps and shows their hand speeds and each golfer’s hand speed slows down dramatically BEFORE impact. That’s when the club releases. The hands actually accelerate before the clubhead is released and the slow down dramatically as the clubhead release happens.

So, this is where I agree with the Endless Belt critics.

However, I do believe part 2 is correct or for the most part is correct. And at the very least a good thing to understand.


Because if one wants to increase clubhead speed they should realize that they need to:

1. Increase Hand Speed


2. Make their ‘pulley’ smaller

I would say the large percentage of professionals have either snap or random sweep releases. Full sweep releases are not very common on the PGA Tour because it’s more difficult to get the fast enough handspeed so you can generate decent power. However, you do see a lot of full sweep releases on the LPGA Tour and it’s a big reason why the LPGA golfers generate slow clubhead speed (and then they make up for it by having an upward attack angle).

So the critics are certainly right in their problems with the Endless Belt concept, but I still find the concept a good concept to learn and understand.



Curro Dorronsoro said...

in the video we can see how Jason Zuback clearly doing a ‘full sweep release’ with a ‘large pulley’.You said that is not a good release for clubhead speed...???????

Rich H. said...

Let me clarify. In order for Zuback to get clubhead speed with a full-sweep release, he needs super fast hand speed. He's obviously a workout freak with gigantic forearms and a big pivot action.

Somebody like Sadlowski, whose 'pulley' is smaller means that he does't need to get the hands moving as fast to generate the same clubhead speed.

Anonymous said...

It's hard to believe JZ's swing to use all of his potential. IMO :-)

Rich H. said...

If Zuback tried to use more of a snap release, he may not hit it anywhere by Long Driving standards. You gotta go with what you can do. So it's really not a potential thing, it's more of 'here's how he generates so much clubhead speed.' He does it by have super fast hand speed and using his strength and pivot. That's why a guy like Sadlowksi can hit it further despite being about 1/2 JZ's size. He can make his pulley smaller and still do it with incredible hand speed.

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Anonymous said...

The physics law at work is conservation of angular momentum. Centrifugal force is the result of the rotation.