Originally Posted by
rickpaulos
The looser the chain, the faster it all wears out. You only have 1 link/tooth at a time taking the pedaling force. Just short of binding and many links are sharing the load.
Biggest problem is cheap bikes where the sprockets aren't running round. The chain goes slack then tightens, and repeats for every pedal revolution. Most common on chinese made bikes with 1 piece cranks. When the chain binds, it puts tremendous pressure on the bearings and destroys them pretty quick. On those you find the tight spot and adjust from there.
The tension changes with both pedal revolutions and cog revolutions. Unless the chainring and sprocket have an integer ratio, like 36:18 or 48:16, it will take numerous crank rotations to get to all of the combinations of positions in order to to find the true tight spot.