It's an absolute finite art Trent, many hours of planning and preparation would have gone in to it. Pages of calculus, algebra, trigonometry and then finally followed up by a game of "eenee meenee minee mo" to decide to the correct bolts to apply the weights to. If you calculated wrong, you have a tailshaft impaled in your shed wall, if you get it right, you will enjoy Mercedes like ride comfort on the highway forever more.