Chain Check'n Time

When I first got into road cycling back in the 80's, the most amount of cogs you could find on a freewheel was 6. Now with todays technology and precision the amount of cogs on a freewheel has increased to 10, 11, and a company called Tiso has developed a 12 speed, so in fact they have doubled. Not only have they doubled, but fit into about the same size space. They do this by making the cogs, spacing, and chain thinner.

 

So in order for to keep your bicycle shifting with precision, it's essential that your chain's wear is within tolerance. The picture above shows a chain checker. It measures the distance between the chains rollers. Your chain should fall between .25 and .50, then anything over .75 needs to be replaced. The chain above measures almost 1.00 so we are going to replace this chain.

So what does the number of .75 mean anyway? As an experiment I made the new chain with the same amount of links as the old chain and lined then up next to each other.

When a chain wears it will become longer. Some people will say their chain has stretched. Your chain does not actually stretch. The chain gets longer because of the cumulative wear between the pins and rollers. A chain might over 200 rollers and pins. So the cumulation of wear of this 104 link chain turns out to be about 10mm. That's just 4/100ths of a mm per pin and roller. Not much, but added together creates eroded performance.

As you can see the old chain is dirty and grimy. Dirt and grim can cause your chain to wear. So keeping your chain clean and oiled is the best way to increase your chain's life.