I’ll give you my view on the subject, plus the theory/conventional wisdom where applicable.
The theory says that once the tube is packed, the penis can only move in one direction, which increases length. In this situation one needs to be very cautious with vac levels as it is only contacting the glans and the glans is more sensitive than shaft.
Theory also says there are two methods of increasing length: lig stretching and cellular replication from stretching and micro tears.
My view on the forces and restrictions involved:
When the cylinder is packed, the penis attempts to move lengthward up the cylinder, which may have the potential to stretch ligs and could also stretch cells. Working against this lengthward force is the friction of the shaft against the cylinder wall. Shaft friction is a result of the penis expanding girthward and exerting force against the restricting cylinder wall. Lubrication can reduce the shaft friction (but does not eliminate it) allowing lengthward movement. Having very loose shaft skin is also helpful to moving lengthward. Too small of a cylinder diameter will also increase the shaft friction.
The question then becomes does the lengthward force offset the shaft friction force enough to allow movement? And the answer depends on the penis. Some may move easily some may not be able to move much.
A little bit of lengthward stretch could induce cellular replication while very limited shaft friction will allow lig stretch and cellular replication.
In my opinion the best way for someone who has packed the tube and now wants to focus on length is to reduce shaft friction as much as possible. Lubrication can only do so much. The next option is to reduce how much shaft is touching the cylinder, suggesting that packing the cylinder halfway (or 1/3 or 2/3) may be a better option. One would need to see how their penis responds and adjust accordingly.
Another option would be to have a cylinder diameter sized so that is just slightly being packed- enough to restrict girth growth but not small enough to substantially increase shaft friction. This is not a feasible option for most due to cost and available cylinder size limitations.
I have read that some guys recommend pumping with a silicon shaft sleeve to constrict girth movement to allow lengthward growth. If the silicon shaft does not touch the cylinder walls you would have full vac level working to stretch the ligs. Not sure how this scenario would work for cellular replication as the sleeve somewhat mimics the cylinder wall when packed.
My personal experience is that I gained almost an inch in length using an oversized cylinder. This is all likely from lig stretch. Once I started using constant heat and a better fitting cylinder, I gained an inch in girth and began packing the cylinder.
Initial: 7” BPEL; 6” NBPEL; 5.25” - 5.5” MEG
Current: 7-7/8” BPEL; 7-3/8” NBPEL; 8.5” BPFSL; 6.5” MEG; 6”x5” Flaccid.
Goal: Improved/consistent EQ while managing ED. Secondary: maintain current stats.
