MOI

[revkev]

I didn't quite know where to put this one so I'll try here.  It's inspired by the blog topic on the R15, along with my experiences with the SLDR and what I've read. 

 

As T aserts in responding to some who responded to his blog there is no denying that the R15 and the SLDR have a lower MOI than any driver on the market.  But I also recall that when OEM's were making a big deal about MOI that Frank Thomason among others stated that after a certain point (somewhere around 5,000) there was a point of diminishing to no real return on a clubs MOI in regards to forgiveness.

 

It's been a long time since I've had accuracy issues with the driver on a regular basis.  I have to say that my SLDR is the most accurate driver that I have ever bagged.  Perhaps I'm just driving the ball straighter this year after my lessons but I'm wicked straight with this thing and can get a little baby draw with it or flight it down or up whenever I want.

 

Any comments on the MOI thing?

[Mr_Theoo]

For me I care about MOI in a driver as much as I do forgiveness in irons. Which ain't much, because I feel a bad swing is going to be the reason for my bad results not the club.

[markb]

MOI and forgiveness with regard to the SLDR is an interesting topic. If we define forgiveness as an ability to deliver the same output regardless of the input, then the SLDR is very forgiving. No matter how I swung it, it produced the same low-slinging draw. It wasn't too long, nor too short and it never went left. I've hit many other drivers that were more erratic and in that sense maybe they were less forgiving. I certainly didn't forgive them for their faults. And my current driver is not the most forgiving one I've hit either. Pop and feel proved to be more alluring.

[tww]

I didn't quite know where to put this one so I'll try here.  It's inspired by the blog topic on the R15, along with my experiences with the SLDR and what I've read. 

 

As T aserts in responding to some who responded to his blog there is no denying that the R15 and the SLDR have a lower MOI than any driver on the market.  But I also recall that when OEM's were making a big deal about MOI that Frank Thomason among others stated that after a certain point (somewhere around 5,000) there was a point of diminishing to no real return on a clubs MOI in regards to forgiveness.

 

It's been a long time since I've had accuracy issues with the driver on a regular basis.  I have to say that my SLDR is the most accurate driver that I have ever bagged.  Perhaps I'm just driving the ball straighter this year after my lessons but I'm wicked straight with this thing and can get a little baby draw with it or flight it down or up whenever I want.

 

Any comments on the MOI thing?

MOI of the head and accuracy with the club are two totally different things and not at all related to each other.  We've done a lot of hit testing as well as FEA impact modeling in this area of head performance over the past many years to know a good bit about this.  

 

In short, it takes a difference of in the order of 800 g-cm2  or more in the MOI of a driver head before most golfers are going to visibly notice a real performance difference in an off center hit.  In other words, if you have one driver with an MOI of 4200 and another at 5000 there is not going to be very much in the way of really noticable difference in the off center hit performance.  But if you get one head at 3800 and the other at 5000, you will see visible differences.   

 

Also as you referred to Frank Thomas' comment in your post, he's right in saying that once you get to an MOI of 5000 with the driver, anything more is really not going to be noticeable.  However another reason for this is because if you are trapped by the USGA Limit of 460cc and if you are forced by length to swingweight matters to keep the driver head weight at no more than 205g, it's almost impossible to design a driver head with an MOI above 5400.  So in that sense Frank's statement is correct because it just isn't feasible to create a driver with an MOI significantly above 5000.  

 

Beyond the MOI, it is a fact that the face design of the driver can have much more of an effect on off center hit performance than another 800 g-cm2 in the head's MOI.  There are some variable thickness face designs which are really good when it comes to keeping the COR of the face for off center locations as high as possible.  Variable thickness faces work by allowing the face to flex inward a little more in the off center hit positions.  And when the face can flex inward a little more in the off center hit positions, the COR there will be higher and from it, the off center hit will not lose very much in the way of ball speed.  

 

IN other words, it is very possible to design a 400cc driver with a 4000 MOI with a good variable thickness face that can offer better off center hit performance than a 460cc driver of 5000 MOI with a uniform thickness face.   

 

Now as to accuracy with a driver, there is nothing other than the face angle that can be designed into a driver head to bring about better accuracy.  Nothing with CG, nothing with the MOI, nothing with the face design or COR has anything to do with accuracy with a driver.   Accuracy is a product of the golfer having exactly the right length, face angle, shaft weight, shaft flex, shaft bend profile, total weight, swingweight and grip size/feel that best matches his swing characteristics.  

 

So if a golfer picks up a new driver and automatically hits it more accurately the reason for the improvement is going to be found within these above fitting specs and how different they are from the golfer's previous driver with which he was not as accurate.