I found this video online. My current driver is at about 45.25 inches long. I am thinking about shortening it.
Now shortening a shaft will make it stiffer, but the guy took a shaft from 45.5 inches down to 43.5 inches. Basically it made it 2 cycles stiffer, so basically a cycle per inch.
For that driver and shaft, they needed to at about 15 grams to the clubhead end to get the swing weight back to its original measurement.
What I didn't know is that adding weight to the clubhead lowers the frequency by a full flex, or 10 cycles.
So basically butt cutting the club by an inch will stiffen it by 1/10 of a flex. Adding weight to the end will make it less stiff by a lot more. In the case of the video a whole flex less stiff.
Though I am not sure about the comments on the flex, as per the Mark Crossfield videos the flex doesn't matter as much as people do make it out to be.
Though I do have reservations about tip trimming a driver shaft. Certain shafts are not very good for tip trimming because they might have an extreme bed profile near the tip, and cutting too much off can change the whole dynamic of the shaft.
Not sure if I want to cut down my driver or not. I might just grip down on it for now. I had my Ping G10 driver cut down and it just felt weird afterwards.