This subject has been approached several different times on the blog and it is an excellent question. My stock answer has been that the dynamics of the swing that we measure in a club fitting will not change that much so the old clubs should fit. I have given this a touch more thought and would like to delve a bit deeper into the question and answer.
First, the assumption is made that the old club fit to begin with. Not knowing what type of fitting or just how thorough the fitting really was, I cannot say with certainty that the clubs as they are fit the old swing much less the new swing. Therefore, if your fitting was done by a big retail chain operation or by anyone that only did a partial fitting, you may want to get a 'second opinion.'
In switching from the flatter rotational swing to the more vertical PPGS swing, there are a few things that perhaps deserve more scrutiny. Let's look at length first.
Some of you that are a tad bit shorter than the average American male and have a shorter wrist to floor measurement have more or less had to swing with the flat rotational style swing. The biggest reason for this is that the off the rack clubs are too long. If you were to swing these long sticks vertically you would be pounding the dirt well before the ball (fat shots). Does this sound familiar to anyone? This would case number 1 where the old clubs would not fit and a change would be needed.
I occasionally see posts on the blogs about distance loss. I think some of this is due to not properly understanding the PPGS fundamentals but I also think some of it can be due to loss of swing speed which results in loss of club head speed. With the long looping rotational swing you were likely to generate more club head speed than going to the ¾ limited turn PPGS swing. This will not be the case with everyone but if you fall into this category then you may need to go to a bit softer more flexible shaft.
Thirdly, the toe down effect and resulting lie angle may need to be checked. If going from the rotational swing to the vertical swing you notice that the toe of the club is making deeper marks in the ground, you will need to have the lie angle adjusted to a more upright position.
Of course as is always the case, see a good fitter. I will post fitter information again in an effort to help you locate someone to help you with your clubs. I appreciate the personal emails asking for fitters in a certain locale', but I would have to use the same web site that I'm going to list below to see if anyone is listed in a particular area. I do not do personal recommendations as a rule other than the three PPGS fitters listed.
Thanks for your continued support of the PPGS, Surge, and the staff. You are the greatest bunch of golfers on the planet!
Better Golf Is Just A Fit Away!
J. Lynn Griffin, Master Fitter/Builder
PPGS Certified Instructor