(light bulb burning bright) IDEA why not use the 35 mm chromoly tubing.....and instead of using the "slug" idea for the axle part...why not just get another set of tubes...or a solid tube to fit INSIDE the outer tubes..further increasing strength under severe shock loads and maybe eliminating the shearing effect of the slugs/spacers in the axle part???? that way it would still be pretty flexible and really decrease the danger factor...maybe put a little oil in between them, so they dont bind on one another.