Chain Wear

[dazdc5]

Just dropped my gauge onto my KMC chain and it rattles around on the 1.00 mark :shock: or how accurate are these tools?

Needing just a new chain or will the whole trans' be fubarred?? XT 10 sp drivetrain. :facepalm:

 

[mattr]

or how accurate are these tools?

Bloody awful.
They measure chain wear plus 2x roller movement.

I tend to use them as a quick and dirty check when the bike gets cleaned or is otherwise up on the stand.
Then if it looks a bit bad, get a 12" rule on the chain to measure the actual wear, pin centre to pin centre.
There are some guides to show how much the extra length/wear will affect the rest of your kit, e.g. ok/nok/new cassette/new driveline

 

[dazdc5]

Re:

I read that the better gauges measured by pushing the rollers the same direction rather that pushing apart, but does measuring with a ruler actually work, as I thought chain stretch didn't actually mean (outer link) chain stretch, more pin and roller wear and mis-match on the sprockets?

 

[Captain Stupido]

Personally I’m happy to trust mine (cyclo) and my experience backs up the theory... I.e. if the guage indicates more than 1% wear the drivetrain is likely to skip once I replace the chain. If I was working on a bike for someone else I’d probably replace chain and cassette to be safe, but if it was for me to ride I’d replace the chain and hope for the best... IME you can get away with a bit more on chainrings and a visual inspection usually tells you what you need to know.

Generally I don’t let chains wear much past .75% if I can help it. Chain wear tool is a reasonable indicator of when the bike’s due (or overdue) a good service.

 

[dazdc5]

Re:

I'm out for a big ride in the Malvern's this Wednesday, I've ordered chain only at this point and should be fitted by Tuesday.

After a test run, if it skips like a bugger, I'll swap back the old chain... enjoy my ride and then swap the two Thursday.

Just hope, there's no snappage and/or crossbar-testicle interaction :shock:

Thanks for your input chaps.

 

[jimo746]

Re:

Aye, you won't know until you try the new chain.
You might get lucky.
Better protect the crown jewels just in case though....

 

[klunkrider]

or how accurate are these tools?

Bloody awful.
They measure chain wear plus 2x roller movement.

...

Then if it looks a bit bad, get a 12" rule on the chain to measure the actual wear, pin centre to pin centre.

Given that the only way the pin centres will separate is for the pins and rollers to wear I don’t see why you think one measurement is more accurate that the other.

 

[mattr]

The pin centres increasing is not linked to roller wear. Just the pin and (inner) side plate wear.
Also, roller wear doesn't really affect how the chain meshes with the sprockets (unless they start to break up of course).

 

[mattr]

Re: Re:

I read that the better gauges measured by pushing the rollers the same direction rather that pushing apart, but does measuring with a ruler actually work, as I thought chain stretch didn't actually mean (outer link) chain stretch, more pin and roller wear and mis-match on the sprockets?

Yes, the better gauges take out roller wear as best they can.
Chain "stretch" is the inner side plates running against the pin (thats where the articulation/friction surface is) and removing material, until your chain "stretches". So the 12" for 24 links plus a wear factor works very well, outer links will always be 1/2", inners will grow as the pins and plates wear.
It's essentially how you measure chain wear in industrial applications.
The roller wear is not particularly relevant to anything much. Except clearances increase as the chain gets more use.

 

[dazdc5]

Re:

Well, as foretold ... the new chain makes it unrideable, so back on with the knackered one for tomorrow and then replace
the rear cassette and hope the triple XT chainrings havn't gone the same way or the cat gets it!

Hang on, I havn't got a cat :facepalm: