Polini crankshaft designed for the 100cc evolution P.R.E.. Engines by Polini for Piaggio zip SP and zip 2 SP scooter. The shaft has a 16mm spline and cheeks also have a larger diameter than conventional Piaggio crankshafts. This is why the crankshaft is specifically developed for the Polini evolution P.R.E.. Crankcase required. It doesn’t get racier than this!