Worn chain and rings

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As someone who had mechanical sympathy beaten into them from youth, I occasionally get the shivers on a group ride listening to a squeaky or dry chain.  My arguably limited imagination can still picture the poor little bearings in the chain heating up and wearing out, especially when blessed by our lovely Dubai hot and dusty riding environment.

Like most regular riders I was aware that chains need regular love, lubrication and replacement; however I had never really witnessed the damage a worn or stretched chain could do until recently.  The term stretched chains is a bit of a misnomer, what actually happens is the little bushings and pins in the links (the bit you are meant to lubricate) gradually wear, becoming slacker and so the chain gradually becomes longer.  The side-plates never stretch; honestly you are not that strong!

chain

One of our regular riding group, asked me to have a look at the shift quality of his Ultegra Di2 bike, as he knew that I had done a couple of installs of Di2 recently.  A quick pre ride look at the bike and a bit of fine adjustment improved things a bit, but the chain was still noisy.  I asked him how long he had used the chain for and he estimated about 7000kms, which I considered as way too long.

Time was tight, but after a bit of discussion I offered to change his chain as I had a new spare Ultegra one lying in the spares department.  One of the ironies of this whole story is that his old chain was so clean and well serviced; I could not tell which the new chain was when we put them side by side; this rider religiously cleans and lubes his chain!

parktool
Park Tool for measuring chain wear

I hate not getting time to check things properly but the quick change was completed and off we went for our regular Monday night training session.   Within a few hundred meters of starting he started to experience his chain jumping on the front 52 tooth chain-ring every time he put any decent power through the pedals.  The gears appeared to be shifting just fine, but the chain kept jumping off.

So I took the bike home to have a proper look and sure enough the new chain had created an even larger problem.  With the bike on a stand it was totally obvious that the front chain ring was completely worn, to the point that the chain was simply not sitting properly on the teeth of the front chain ring and a space could be seen below every link.

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Totally knackered chain ring, note the sharp teeth and lack of squared edges

It seems obvious but when you pair a new chain with worn cassette/rings you are opening the door to complications like skipping. If you have a worn chain on a worn cassette/rings the chain links line up with the teeth. If you put a new chain on, the links don’t line up nicely with the worn teeth.

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This is what a new chain ring looks like, note the squared off teeth and deep valleys

The end result is the bike now needs, both front chain rings, the cassette and the chain all replaced which at Dubai prices, just for the parts of over 1200aed is a bit of a hefty bill.  The moral of the story is cleaning and lubing your chain is great, but not enough.  If you can hear any significant noise from your chain, you are listening to wear.  You should implement a regular chain replacement schedule, so that your chain never gets so elongated or worn that it wears out your expensive rings and cassette.

If you are a regular rider trying to do lots of KM’s, consider changing your chain around every 3-4000km or when measurably worn, gritty or noisy.

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One quick and easy way to tell if your chain is worn is to pull the chain as in this picture, if you can see even close to that much space, your chain is ready to be replaced

Chains are pretty cheap from Merlin or Evans, Ultegra ones come out at just over 100aed shipped from Merlin, so keep a couple in stock and if you need to learn how to change them, YouTube has numerous videos on how to do it.  Apart from not getting Cranky complaints from fellow riders, the other bonus is your bike will love you, changing gears with the slickness of a financial advisers sales pitch.

This is what a new chain looks like when tested the same way
This is what a new chain looks like when tested the same way

Crank.

One thought on “Worn chain and rings”

  1. If you discover the damage to your chain ring, as in the photo, you can extend the life of the chain ring by using a round file to reshape the teeth on the worn side.
    This is not the preferred remedy, but if you cannot afford a new chain ring or if you cannot obtain one quickly, then this will extend the life of your old one until you can.

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