I have just read an article in 40 years on by Jacqueline Bickerstaff. She talks about vibration moments. How they vary according to frame and cylinder orientation. I think people need to get a handle on the fact that without a contra rotating balance shaft there will always be vibration somewhere. Personally, I would want that vibration at 120 mph because I will never be there. At the moment I have a Rapide and a Shadow that vibrate at 70mph. That really, really, annoys me. I am now going to put a 46T rear sprocket back on the Rapide so the vibration hits at closer to 80mph. BUT do I increase or decrease the balance on the shadow so vibration comes in at either 30 mph or 110 mph? Basically I want 50-80mph smooth in top or third. Over to you.