Should my chain have tight spots? Unfortunately yes, all chains get tight spots.
You see, to all intense and purposes every link of your chain is the same and the friction in each one should feel the same. Actually, they are not totally identical because no two things ever are. It is all a matter of degree of measurement. Just like a needle feels very sharp if you stick it in your finger, but if you look at it under a big enough microscope its head is as blunt as a hammer head. It is all a matter of degree. None the less, to all intents and purposes they are the same.
So we have a world class chain which has been manufactured in our computer controlled factory and provided the joining link is correctly fitted there should be no tight spots. The trouble is from here everything starts going down hill.
Firstly. They are for the most part lubricated with an aerosol can by human hand. This means that each link gets a different amount of lubricant and is therefore no longer the same as its neighbour. Next, the road or track throws up all sorts of gravel and debris and again the amount of this that comes into contact with each roller and pin varies. Go off road and the situation gets even worse! The result of all of these ‘uncontrolled’ elements means that each roller wears differently and as a result there will always be a loosest and a tightest spot. It would be possible to avoid it if we changed the bikes to run fully enclosed chain cases and ran them in a permanent bath of oil rather like the cam chain in an engine, but as things stand, all chains get tight spots. The best we can do is to lubricate tension and align them correctly in an effort to minimise the affect.