I recently bought a chain splitter tool from eBay and this morning tired it out. I did eventually manage to drive the chain pin thru with the tool but only by removing one of the tool pins. Which left me wondering why the tool has two adjustable pins in it.



This is the type of tool and on the left is the pin that I removed. Can anyone tell me what purpose this pin serves?

I believe that part on the left is referred to as the "anvil". On that particular tool it seems the anvil is adjustable.

The knurled "pin" or anvil on the left is adjustable for various width chains. For example older 5-speed chains and track chains are wider than newer 8,9, 10 and 11-speed chains. You place the chain over the shelf to the left, adjust the anvil so it's snug against the chain and push out the pin with the screw press.

The other shelf is the "loosening shelf" and is used to slightly spread the chain to free up a tight link. It should not be needed with modern chains if the special joining pin (Shimano) or master link (most others) are used.

yes , new bushing-less, flush pin chains, you only shorten them, and close with the Quick-link pin

the Lateral flexibility of derailleur chains now

can come apart after pushing rivet pins out. thus stretching the link hole..

Thanks but I still dont understand how you can push out a pin when the anvil is pressed against the pin from the other side. Anyhoo, I did manage it eventually once I had removed the anvil.

Right, think that I understand it now. It is a peening anvil and used to spread the end of the rivet once it has been pushed thru the chain to prevent it from being damaged or falling out......... or something like this.

Yes, that's correct. I couldn't tell from the picture if that "anvil" was hollow and let you push the pin through it or was a riveting face to let you "peen" the pin in place.