Thursday, November 12, 2009

Check Your Chain

Just about all cyclists know the correlation between a clean, well lubricated chain and proper shifting performance. However, not many cyclists take the time to check the wear of chains and cassettes. A worn chain by itself won't contribute to poor shifting. However, a worn chain will lead to greater wear on the cassette. A worn cassette will inevitably lead to ghost shifting and very poor shifting performance.

Chain wear is often referred to as "strech." The actual part of the chain that stretches are the holes in the plates which contain the chain pins or bushings. For an in depth explanation on all things related to bicycle chains, Sheldon Brown's bicycle bible is a great read. A properly lubricated and cleaned chain should provide between 2,000 and 5,000 miles of service. However, dirt, debris, and friction can lead to premature wear. But how do you know when to change your chain?

The good news is that everyone has the basic tools required to measure chain wear - a simple ruler. Twelve links in a brand new chain should measure 12 inches. When the twelve chain links measure 12 1/16 inches or more, it's time to replace your chain. This is a reliable method. However, it's not always the easiest or most convenient method. Thankfully, there are affordable specialty tools which can accurately and easily measure chain wear.

A simple measuring tape is all that's required to measure chain wear

Park Tool makes a simple CC-3 template gauge that inserts between the links of a chain. The CC-3 is a "go" or "no go" gauge. There are two sides, one which indicates .75% of chain stretch and 1.0% of chain stretch. If the .75% side doesn't fit, chain is like new and you're good to go. If the .75 side fits, time to start pricing a new chain. If the 1.0% side fits, you'd better run to your local bike store for a new chain. This simple, but effective tool can be had for between $7 and $10 from any Park Tool dealer.

A second option is the Park Tool CC-2 Chain Checker. For people who want to know exactly how fast their chain is wearing or a more accurate measure of chain wear, the CC-2 is the tool you need. You simply insert the two pins into the links and swing the gauge tight to see exactly what percentage your chain has stretched.

At .5% stretch I will start examining my chain more often for wear

The best thing you can do to promote long chain life is keep it clean and well lubricated. The next is taking some time each month to see just how it has worn. Keeping your chain well maintained will ensure many miles of trouble free cycling.

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