AndyMark Sonic Shifter with Approximately with 3 ft/s low and 13 ft/s high. The Chains are tensioned by pulling on pillow blocks that the wheels are attached. The center is dropped 1/8 of an inch currently running 4 in wheels.
In our experience, if the chain is of proper, and you use #35 roller chain, you do not need a tensioner, though it is a nice luxury if you want to spend the extra time to build them. Also, did you do any extra gearing on the Sonic Shifter or is it all stock? It’s a nice simple drive, and I like the overall design. Is that aluminum I-Beam?