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Friends - My "go-to" truss rod for my basses has been the rod sold by LMII; however, since they are now out of business, I am evaluating what other rods are suitable for bass guitar necks. The attached photos are all showing truss rod lengths from the front edge of the nut slot location on the blank. One photo shows my last LMII rod (23 1/2" in length) vs. 2 other rods, one longer (23 11/16") and one shorter (22 1/4") -- all measured from the front of the nut slot.

I make a standard F-style, 20-fret bass neck with a nut width slightly wider than a standard P Bass (1.73").

Is there a "rule of thumb" that guides the overall length of the truss rod relative to the length of the neck itself? I am concerned that the shorter rod shown is too short and that the longer one may actually be too long for this length neck blank. Does it matter for a bolt-on neck since the heel is fixed to the body anyway?

Am I over-thinking this or not?? ;)