Cycling UK Forum

I wanted to check chain wear on my road bike so used two of the usual tests:
1) Used a chain checker which would not squeeze into the links, so proves there is no wear yet
2) Pulled the chain at 3 points on the large ring. This pulls away from the teeth a good 2 mm. So does this mean I need a new chain, and why does the checker tool not show this?
The teeth are all fine, cassette and both front rings.

Some previous expert discussions:
viewtopic.php?t=115336
viewtopic.php?t=157092
viewtopic.php?t=142494

Jonathan

fastrack1966 wrote: ↑14 Aug 2023, 2:10pm I wanted to check chain wear on my road bike so used two of the usual tests:
1) Used a chain checker which would not squeeze into the links, so proves there is no wear yet
2) Pulled the chain at 3 points on the large ring. This pulls away from the teeth a good 2 mm. So does this mean I need a new chain, and why does the checker tool not show this?
The teeth are all fine, cassette and both front rings.

In future just use one test and go with the result

fastrack1966 wrote: ↑14 Aug 2023, 2:10pm I wanted to check chain wear on my road bike so used two of the usual tests:
1) Used a chain checker which would not squeeze into the links, so proves there is no wear yet
2) Pulled the chain at 3 points on the large ring. This pulls away from the teeth a good 2 mm. So does this mean I need a new chain, and why does the checker tool not show this?
The teeth are all fine, cassette and both front rings.

The checker tool does not show any wear because pulling the chain away from the teeth is a time-honoured piece of cycling nonsense that doesn't really tell anyone anything!

Most chain checkers are also inaccurate, but in the same direction: they also make out that chains are more worn than they really are.

Use a ruler.

Chain checker tools that use a 3rd prong to ensure the measurement is between rollers pushed in the same direction aren't too bad.
Examples: Park CC4, Pedros CC Plus II, Shimano CN42.

Most others only use two prongs, measuring between rollers pushed in opposite directions. That adds (irrelevant) roller wear into the measurement that has to be allowed for by guesswork, and since a new chain skipping would generate more complaints that an old chain being unknowingly discarded early, the checkers are generally set to indicate more wear than actual. It's not unknown for an unused chain to show as in need of replacement.

A ruler is just as good, and gives some indication of how long to go rather than just good/no good. The disadvantage is oily fingers.
Ruler measurement is 12 1/8" between pins nominally 12" apart is 1% wear. Change at 1/16" or 3/32" according to inclination.

CJ wrote: ↑14 Aug 2023, 3:48pm The checker tool does not show any wear because pulling the chain away from the teeth is a time-honoured piece of cycling nonsense that doesn't really tell anyone anything!

This! ^^

How have you checked for chain wear in the past? How worn are you expecting it to be - is it a couple of years old or relatively new, what use has it had and in what conditions? And what groupset / bike is it on - lower end of the spectrum tends to wear everything together since it's more likely to be using cheap pressed steel rings but that doesn't necessarily translate to obvious indications that the chain is worn.

richardfm wrote: ↑14 Aug 2023, 3:46pm In future just use one test and go with the result

This made me smile. But perhaps we should extrapolate further:

If one test is better than three, then none must be better still. So in future just continue in ignorance.

andrew_s wrote: ↑14 Aug 2023, 6:08pm Chain checker tools that use a 3rd prong to ensure the measurement is between rollers pushed in the same direction aren't too bad.
Examples: Park CC4, Pedros CC Plus II, Shimano CN42.

Thanks Andrew - I thought Shimano was the only one to make that design, but the CN42 has always been both over priced and hard to find.

My preferred method is taking the chain off and hanging it on a horizontal piece of spoke or similar, side by side with a brand-new chain. You can clearly assess the elongation by comparing the position of the last links or equivalent links, let's say the 114th or 116th on both chains
If the used chain is more than half a link longer, then I replace it. That means the elongation is close to 0.5%. Half a link would be exactly 0.5% in a 100-link chain. I use 114 and 116, so half a link, at the last link, is safely below 0.5%.
Easy to do, no tool required, every time you take a chain off for a thorough cleaning.

TheBomber wrote: ↑14 Aug 2023, 7:29pm

richardfm wrote: ↑14 Aug 2023, 3:46pm In future just use one test and go with the result

This made me smile. But perhaps we should extrapolate further:

If one test is better than three, then none must be better still. So in future just continue in ignorance.

I should have said one method. By all means repeat the test a number of times to be sure of the result

CJ wrote: ↑14 Aug 2023, 3:48pm The checker tool does not show any wear because pulling the chain away from the teeth is a time-honoured piece of cycling nonsense that doesn't really tell anyone anything!

I'd like to know more about this; I've always thought it was a handy "rule of thumb" sort of thing. If you give the chain a tug (say during cleaning, or some other task) and it comes miles off the chainring, it's worth thinking about wear. Seems to fit my experience, any roood ...

I've no idea what "amount of daylight" means some wear, lots of wear, throw it away etc. But I a curious!

Well a new chain will pull further off a worn chainring than new one so its a bit arbitrary at best.