Varitech Best Adjustable Stroke Crank Mechanisms Developer 2021 I am Ray O Donnell chief designer from Varitech. Multitudes of hours have been spent on this unique design. I also noticed that designers were stuck with varying the conrod length and not the crankshaft stroke. This is where I started with a different variable stroke building many prototypes in the single cylinder models. Finally I stumbled on a design that seemed to do the trick so I patented it. At this point I created my company