Now that I've added that 1" coil on top, it's nearly rigid, anyway. I set my gut over the bars, hiked my Chuck Taylors up off the ground, and did fat man planks. It didn't even come close to bottoming out, though I had to catch my breath for a moment, after all of that exertion.WOW!! Just now catching up on this build! It is looking super slick! You always have a killer stash of cool stuff, so it's always fun watching you try it all out. What a beauty so far! If you are worried about the wheel hitting the stationary fender and fork leg, you could always sleeve the spring center bolt with a piece of pipe to make it a stationary faux springer.