A low profile tension adjuster for use with a chain or belt driven power transmission system which has a slidable bar that sits inside of a yoke and over an axle and a base plate and set screw arrangement that abuts the slidable bar. The set screw and base plate being utilized to force the slidable bar into a positive fixed contact with the inside yoke end and then force the base plate and axle rearward in order to tighten the chain or belt power transmission system. The entire tension adjuster being generally cylindrical in shape and not extending beyond the ends of the yoke.