The stretching of a chain - what it looks like

[johnny]

Popped this chain yesterday, (at the furthest point from the car...), as I was shifting down climbing a sharp little incline, with pretty minimal force - I was still seated at the time.

I knew I was getting close to the end of the life of this chain and should have replaced it before now. Measured it with a new chain and was pretty surprised at how much they actually stretch.

This is the chain adjusted at the starting point so the links at the other end are in line

 

[Kind_cir]

I remember years ago using a metal ruler to measure the streach. It’s more eye opening when using a ruler.
But in reality, it wears, which gives the illusion it has stretched

 

[moorey]

Yep. Did this the other day with Felix’s mates chain when my checker wasn’t handy. A full link different over about 108 links. It had munted his cassette. Luckily I was swapping that too.

 

[Flow-Rider]

It's normally above 3mm max of stretch per 12 inch of chain then it's truly screwed. Say you have 112 link chain, you have about a max stretch limit of 27.99mm over the whole chain, which happens to be more than one virgin link of chain.

 

[The Duckmeister]

You might want to revcal

It's normally above 3mm max of stretch per 12 inch of chain then it's truly screwed. Say you have 112 link chain, you have about a max stretch limit of 27.99mm over the whole chain, which happens to be more than one virgin link of chain.

You might want to recalculate that... 12" of fresh chain is 24 links. A 112-link chain is 56" long when unworn. 3mm per 12" wear over that length is 14mm. Which is still more than one link, not the two links you're working on.

 

[johnny]

So this chain was stretched about 2/3 of a link when it gave out, catastrophically and under pretty low stress. Not sure how long it was but came from a typical 1/10 setup running a shadow XT.

I’m actually very grateful that it gave out when it did, rather than on the road, around cars, when I’m out of the saddle and laying the power down.

Was a timely reminder not to neglect important issues that stand to impact wellbeing (and also, potentially bringing testicles in contact with top tube with significant force).

 

[Flow-Rider]

So this chain was stretched about 2/3 of a link when it gave out, catastrophically and under pretty low stress. Not sure how long it was but came from a typical 1/10 setup running a shadow XT.

I’m actually very grateful that it gave out when it did, rather than on the road, around cars, when I’m out of the saddle and laying the power down.

Was a timely reminder not to neglect important issues that stand to impact wellbeing (and also, potentially bringing testicles in contact with top tube with significant force).

Where did your chain break ? Did it pop a side link off or break where something was worn thin. If you have had a previous hard pedal strike, it can stress a chain and loosen the pin in the outer plate enough to split the chain later on, I've seen fairly new chains pop open like that.

 

[link1896]

I've never liked chain checkers that push against rollers, as rollers wear too.

Measuring 10 or 20 links of plates with calipers, or hanging chains off a parallel nail is a more reliable method.

 

[hifiandmtb]

Tomorrows rant will be "wheel building is not an art - it's engineering, get over it".

Please do, like this:

https://www.pinkbike.com/u/Whipperman/blog/biggerstronger--calling-bs-on-super-boost.html

I like reading stuff like this.

 

[Dales Cannon]

Johnny how much slop is there pushing links together and pulling them apart?

 

[John U]

I had a relatively new chain break repeatedly (a long time ago, 8 speed). Don’t think I’ve had a chain break since despite wear.

 

[moorey]

I agree the latter is most accurate but the checkers that slot in between links are fine. While they push against the pins, that's not different to the chain being under tension from its run between the cassette and the chainring.

My thoughts also...

As does a chain hanging up carrying it weight.

 

[Flow-Rider]

I had a relatively new chain break repeatedly (a long time ago, 8 speed). Don’t think I’ve had a chain break since despite wear.

I had friend that hit one of those Grass trees with his pedal on a brand new Trance and a few hundred meters down the trail the chain split, another time I heard a bad gear shift in a riding group I was with and their chain broke soon after.

I'm not too sure how accurate it is measuring from pin to pin unless you change the chain early in the piece as a safe guard because if you try and get the most out of a chain with this method, you're relying on how uniform and central the pins have been riveted on the plates and it might be enough to push you over the edge.

It's the pitch growth of the chain that causes your cog teeth to wear and chain to slip, that measurement will be the most when you have the biggest load on the chain, like when you climb a steep hill.

 

[Cardy George]

This is the first bike I've given any attention to chain wear. Normally I just wet lube and ride, then replace the whole box and dice at about 20,000.

Shite, that reminds me, better order a chain checker

 

[John U]

I had friend that hit one of Grass trees with his pedal on a brand new Trance and a few hundred meters down the trail the chain split, another time I heard a bad gear shift in a riding group I was with and their chain broke soon after.

I'm not too sure how accurate it is measuring from pin to pin unless you change the chain early in the piece as a safe guard because if you try and get the most out of a chain with this method, you're relying on how uniform and central the pins have been riveted on the plates and it might be enough to push you over the edge.

It's the pitch growth of the chain that causes your cog teeth to wear and chain to slip, that measurement will be the most when you have the biggest load on the chain, like when you climb a steep hill.

The Park chain checkers have a bit of tolerance built in for pin placement and other stuff. The lower measurements on their checkers have a range for New Chain. I know this because I misinterpreted this when I first got my chain checker. I tossed a couple of perfectly good chains before I realised. Should be an entry in the fuck heads thread.

 

[The Duckmeister]

I've never liked chain checkers that push against rollers, as rollers wear too..

Indeed they do, but so to do the spigots on the inner links which the rollers run on & pins go through, and the pins themselves. It's the wear on the inner links & pins in particular which gives the impression of the chain "stretching".

I had an absolute doozy come through the workshop only a day or two before this thread started which claerly showed some heavy wear on the extracted pin, which would have illustrated this thread quite well. Without the benefit of foresight I chucked it rather than taking a photo of it.