Chain wear confusion

SME

I have one of those Parktool chain wear gauges that has a 0.5. reading on one side and a 0.75 on the other.

When I see YouTube videos of how to use them it's generally stated that if the smaller tip drops into the link the chain will need replacing - if it's the longer/bigger side that drops in the the chain and sprockets are probably beyond their service life.

So far, no problem... Except

Some of these chain wear gauges/checkers seem to be marked 0.5/0.75 (as mine), and some seem to be 0.75/1.0. How do I know if I have the right gauge and at what point my chain needs changing?

I've also done the '12 links measure 12 inches' test and there seems hardly any stretch. I'm doing London to Brighton and back for CRUK in September and obviously a few decent training rides beforehand - should I change my chain at the '0.5 wear mark'?

Confused!

drlodge

I just look at my chain when on the big chain ring and check visually to see if its stretched.

keef66

I have the Park Tool one with 0.5 and 0.75. At 0.5 I start looking for the spare chain I bought a year ago and put somewhere safe. Eventually I'll find it, or realise I've already fitted it and order another, but I only replace it when it gets to 0.75. If / when a new chain keeps skipping on the worn cassette, and doesn't settle down in a couple of rides I'll replace the cassette too. Get at least 4 chains per cassette this way.

I accept that this kind of chain wear checker errs on the pessimistic side and I'm likely to be replacing things before they are properly worn out, but I don't do intergalactic mileage like some on here, and it's meant I've yet to wear out a chainring. It is quick and easy to do, so I tend to remember to check the chains fairly often.

I've tried the faffing about with a steel ruler, but I can't hold both ends still enough to take an accurate measurement, my eyesight isn't what it once was, and I and the ruler end up covered in chain lube.

sungod

tbh i just hold a steel rule against the chain while it's on the bike (though these days i need more light to read it than a few years ago!)

SME

So the 0.5 is a bit of a warning, I guess. The stretch measured on a ruler is barely perceptible, and the links aren't much looser on the chainring than I remember a new chain being.

I'll keep my eye on it for mow...
Thanks for the replies.

Steve

svetty

keef66 wrote:

I have the Park Tool one with 0.5 and 0.75. At 0.5 I start looking for the spare chain I bought a year ago and put somewhere safe. Eventually I'll find it, or realise I've already fitted it and order another, but I only replace it when it gets to 0.75. If / when a new chain keeps skipping on the worn cassette, and doesn't settle down in a couple of rides I'll replace the cassette too. Get at least 4 chains per cassette this way.

Exactly what I do!

SME

Svetty wrote:

keef66 wrote:

I have the Park Tool one with 0.5 and 0.75. At 0.5 I start looking for the spare chain I bought a year ago and put somewhere safe. Eventually I'll find it, or realise I've already fitted it and order another, but I only replace it when it gets to 0.75. If / when a new chain keeps skipping on the worn cassette, and doesn't settle down in a couple of rides I'll replace the cassette too. Get at least 4 chains per cassette this way.

Exactly what I do!

Cheers. Feel reassured a bit now. I'll wait until the 0.75 drops in.

shmooster

sungod wrote:

tbh i just hold a steel rule against the chain while it's on the bike (though these days i need more light to read it than a few years ago!)

This.

I also find a worn chain jumps occasionally when changing on the front, that's usually my first indicator.