The last shaft drive bikes i saw were in the late 90s with the name "Oxford" on them. I think making gears precisely enough to have a free-running drivetrain was too much to expect for the $400 or so the were selling for. The drivetrain felt notchy and had a lot of drag. I have never heard of "Dynamic." Almost all bikes are made by large Asian manufacturing businesses and the same product is often sold in different places under different names, or exported in great numbers to one place and not exist in another.