how does cutting shaft length affect flex?

[RandyBobbitt]

I've always heard that altering the length of a shaft affects its flex, with the formula being 1 inch = one flex. I recently cut one inch off the grip end of the stock shaft on a Cobra Long Tom driver (48 to 47 inches). If it was a senior shaft at 48 inches, did that make it now the equivalent of an R shaft? I have an 88 mph swing speed and have R shafts on all my other clubs. With the Cobra, I get good results downwind or into a crosswind, but against the wind the ball tends to sail upward, losing about 20 yards over a typical drive. Is this problem caused by the shaft, my swing, or the dimple pattern on the ball?

[Shindig]

Which end did you cut from? My understanding is that cutting from the tip changes flex, while the butt changes length. When I build a club, I cut the tip to get the flex I want (R, S, +/- soft step/hard step, etc), connect it to the head, and then cut to playing length from the butt.

[mvmac]

With the Cobra, I get good results downwind or into a crosswind, but against the wind the ball tends to sail upward, losing about 20 yards over a typical drive. Is this problem caused by the shaft, my swing, or the dimple pattern on the ball?

Do you have any idea what your angle of attack is? If it's negative, then this could be the problem.

[WUTiger]

Trimming the tip will stiffen a shaft noticeably. You should consult the shaft's trim chart to determine the stiffness change.

Technically, trimming the butt stiffens it a little, a slight fraction change you wouldn't notice for an inch. Trimming from the butt will change the swingweight, about 3 points per half inch. So, your club is now 6 swingweights lighter (assuming you regrip with the same weight grip).

As for the ball ballooning, any of the three could be a factor. A good clubfitter could advise you on dynamics of particular shaft you have (either Blackbird or RIP?)

Quote from a Long Tom ad...

Option to have this club built for you, either 48" Blackbird 50 gram or *Aldila RIP Alpha 60 gram shaft and Winn Lite Firm Black grip.

*Aldila RIP Alpha standard shaft length is 45.75". We can custom build this club up to 47.25" length. Please call 760-276-4600 after placing the order if you would like custom length.

Full ad: http://www.cobragolf.com/long-tom-long-drive

[MS256]

Disclaimer: I have no clue what I'm talking about.

I have shortened a driver from the butt end from 46 inches to 45 inches and I would say the difference in flex was slightly noticeable.

I would guess that going from 48 inches to 47 inches would change the flex less noticeably than going from 46 to 45. Sort of a sliding scale based on how long the club was to begin with.

Maybe one of the engineers can say if my theory holds any water.