Originally Posted by killsurfcity
i had a similar issue with the variable tightness, so just to be sure i re-packed my bottom bracket (with the tightness came squeaking) and discovered that one of the BB cups had worn unevenly and was causing my crank to shift at the axle.
You can test for this by taking the chain off. If the tight spot is still there with the chain disengaged, I would think the bb is your culprit.