I was in the process of replacing my bungees, and thought I'd do a stretch test with the old ones to see how bad they were, and check out the engineering behnd their use as the landing gear springs. In my stretch test I used a fish scale and tape measure to determine the spring charactrristics, Force vs. Length. I zip-tied one end and looped the other around the fish scale's hook, then stretched it with a boat winch. What resulted was a sideways S-shaped curve, showing what anyone who has used a slingshot knows: that a rubber spring eventually stops stretching at some load, even as load is increased. The Hook's law spring constant is high at the low-force end, but also becomes much higher at the high-force end, and is lower, but slowly increasing in the midrange. Weird, but likely related to the molecular structure of rubber.
Knowing that a spring's stiffness is inversely proportional to length, I then applied the stretch data to the loop geometry of the Avid's landing gear. It's convenient that in re-wrapping the bungees, the force required is totally manageable, due to the 7 wraps used. Of course this means we are applying a preload. At this point we are stretching the bungees to 132% of their no-load length. Of greatest interest to me was the realization that the bungees stretch up to 172% of their no-load length. It is here that the bungees stop stretching, even as force is increased further. Half of the bungee-centerline wrap distance is 8.5", and with 90" no-load length and 7 wraps (14 strands) each strand's no-ĺoad length is 6.43". Stetching stops at 172% of no-load length, so full extension should be reached at 3.4", not the 3" prescribed in the build manual! The safety cable is only there to prevent total collapse, but if it's shorter than full extension, you risk bending & crimping the thinwall tube under your seat; the tube the bungees wrap around, if you land too hard. The bungees wouldn't be able to absorb the energy before the merciless cable comes into play! That cable applies a point load to the tube, not distributed like that of the bungee.
So those are the results of my analysis. Am I nuts? I'm sure others in the group have thought thru this as well.
Making up my new bungees, a special thanks is due to Fred, who showed an elegant approach!