Chain-link-shaped hole in chain wear tool

[gaijintendo]

Any idea what the hole is for?

My best guess is it helps you find it in the toolbox.
The other is presumably for wall mounting.

 

[gaijintendo]

?

 

[Heltor Chasca]

It is for shelling peanuts.

 

[Alex H]

To remind you what the tool is for?

 

[Oldfentiger]

I was pondering this very question last week.
I don't know the answer, but if you offer it up to the chain with the link shaped hole over a link, then a chain pin appears in the centre of the oval hole.
Maybe it's a visual representation of wear in the chain?

 

[gaijintendo]

To remind you what the tool is for?

Sounds reasonable to me.

I was pondering this very question last week.
I don't know the answer, but if you offer it up to the chain with the link shaped hole over a link, then a chain pin appears in the centre of the oval hole.
Maybe it's a visual representation of wear in the chain?

That would make some sense. How far along the hole is the pin.... Hmm.

 

[Ajax Bay]

if you offer it up to the chain with the link shaped hole over a link, then a chain pin appears in the centre of the oval hole. Maybe it's a visual representation of wear in the chain?

I've measured mine ("Mighty") and if the chain pin in the oval hole is central, the distance between 3 links is 76.8mm. Three inches is 76.2mm so this would represent an elongation of about 0.8% (and any further apart would be replacement time). Measuring only three links is prone to errors given parallax etc.
I've had my chain off after 1600km and assumed it might need replacing but no measurable elongation (steel rule over over 20 inches). The tool backs that up (not that I trust it over a steel rule). So the (now clean) chain's gone back on.