Smooth transitions between curved and straight lines?

Always struggled with this but never got round to finding the solution. How do i avoid those strange optical bumps when joining a curved line to a straight line?

Best way to illustrate the problem is drawing a right angle then adding a rounded corner. Where the new rounded corner meets the straight line the transition between the two is too abrupt and creates an optical bump. It feels like the curvature needs to ease into the straight part instead of changing so abruptly but how do i draw this accurately and consistently across different curves and angles?

The red sketch attached is an exaggerated drawing of the bumps i'm seeing.