What exactly happens to club if you shorten the shaft?

Thanks again Foxholer!

Now, the question is - how much can I tell that I want it shorter from trying to grip it lower? Is it a good approximation of the end product feel? Obviously it won't be the same, so is it worth trying to play with lowered grip, can I get any valuable information from it?

Gripping down will give you a resonably good approximation as to how it will feel, but it won't actually be 'the same'! That's because the grip will be thinner at the point you grip down to and, , more importantly, the excess will be acting as a very slight counterbalance - which will affect the swing weight - while you are doing so. However, unless you are particularly sensitive to this sort of thing, then, imo, you won't notice it after a couple of swings!

Cheers the_coach!

The only thing I do not understand from what you wrote is the "10g = 2 cycle" thing. First - what is a cycle frequency? Second - will adding weight to club head / shaft tip make the end product less stiff?

The 'cycles' are the result of measurement on a CPM machine, which is the standard way in which shafts flexes are measured - though it's only relevant to 'identical' profile/weight shafts, as these vary across different styles and brands of shaft. The uncut shaft is put in a 'grip' (5 inches from the butt from memory) and the tip tweaked. The frequency at which the shaft oscillates is a measure of how stiff that shaft is. A Stiff shaft may oscillate at round 253 cpm; an X Flex at around 263cpm. As a comparison, several 'prototypes' apparently headed for Tiger Woods's testing were rated at 280pm!

CPM measurement is not an entirely satisfactory way of comparing different shafts (the butt attribute dominates) and Cleveland (through their subsidary Miyazaki) proposed an 'International Standard' method - that has not been adopted - of rating the flex at 4 different points. The reason for doing that is that the different profiles can be seen rather clearer, so individual player preference/requirements can be gleaned better!

CPM does, however, allow a set of shafts (for irons) to be matched, as the profile of the individual shafts is pretty consistent. This is what 'Frequency Matching', as opposed to 'Weight Matching' is all about.

Adding weight to the head will indeed make the shaft feel less stiff. Again, depending on the amount of weight, this might not be noticeable, but for those who are particularly sensitive, the tape can be added near the ferrule and balanced by some under the grip. Again, I believe that, except for rare.particularly finnicky folk, the difference will not be noticed after a couple of swings!