I've only gained 0.4" BPSFL since May (four months at 0.05" per month), and my pace feels glacial. Part of the issue was I couldn't get enough tension on my vac ADS (I've slowly needed more & more traction to create reasonable strain, but the device was slipping when I tried to use significant weight).
I COULD switch to my Bib hanger (its a great device & I used it for years in the past) but I prefer Vac ADS for comfort & prefer "set it & forget it".
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How I Hacked my Vac ADS to handle more tension:
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Summary: I doubled-up on tubes with a thinner, ultra tight one underneath & now I can use far more tension on the strap without device slippage. I also arranged parts to fit perfectly together, so the only "lube" I need is water & this prevents the vac valve from getting clogged (which ruins the vacuum seal).
1-StealthForMen Vac ADS (you could do this with any brand probably though)
2-Sabreskin: size 30 (the bigger reddish brown tube)
3-Sabreskin: size 28 (the smaller brown tube -- cut to fit behind glans cap under the bigger tube)
4-Glans Cap: Size 32 (clear silicon tubing - cut shorter than usual by about 3/16")
5-Chamber: Size 32 - the clear hard-plastic shell
6-Vac Seal - goes on top of sabreskin & allows the chamber to seal with vacuum pressure.
Notice how each part is progressively a different size? My parts kept breaking when I attempted to use a 32 sabresin and 32 glans cap/ chamber; at least in my experience its also impossible to get things to connect without cocunut oil or some kind of lube if everything is the same size... Then the coconut oil clogs the vacum valve & the chamber is potentially ruined (sometimes cleaning doesn't seem to work).
-I've now gone maybe 6 months with this device where parts aren't CONSTANTLY breaking (I broke several glans caps & vac seals; those break fast if sizing is wrong); and sometimes the chambers have stopped working (probably due to being clogged with coconut oil).
-I ONLY use a small amount WATER now to get the device on (and it works well enough as a "lube" without clogging anything, but it's only possible with parts that fit perfectly together).
Heat: Although I warm up with 10 minutes of pumping, I would eventually cool off during my 2.5 hour vac ADS sessions, so I use an FIR heating pad... I go by "feel" where I get it as warm as I can without being uncomfortable. Idea here is maximize malleability of my tissues (this is well known based on published medical research and its why good physical therapists always use heat before stretching tendons/ tissues).
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Calculating Strain:
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Medical research shows that 4% to 5% is perfect levels of "strain" to maximize tissue growth, and that 8% or higher results in damage & injuries. Anecdotal evidence among PE'ers shows 2% to 4% strain works well for most guys. Going past 5% strain (with tissue in general) tends to result in a negative reaction where the tissues resist growth (and in PE that means we make tissues stronger & fail to grow).
Formula:
Target Length=Starting Length × (1+Strain %)
Starting Length: I measure BPFSL right before I put on my vac ADS device (8.5" currently)
Target Length: Use the formula & stay ideally within the safe 2% to 4% range.
2% strain:
8.50×1.02 = 8.67″
4% strain:
8.50×1.04 = 8.84″
5% strain:
8.50×1.05= 8.93″
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Results: 2-4% Strain is possible now with the added tension
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Doubling up on sabre-skin tubes with a thinner inner tube is providing far better traction for me (without discomfort) and the device no longer slips with higher tension.
Note: in my case, my glans cap was too long, and I had to slice that shorter too (to prevent it from pinching skin against the inner sabreskin tube)
My BPFSL is growing faster again and I'm able to hit 4% strain for the first time in a very long time, because my device can support far more tension. I estimate that I'm using 7-10lbs of force now. I recently gained 0.125" after stalling for months, and it happened a few months after increasing my vac ADS force.