How a Chain Tool works

If your chain snaps mid-ride, this quick fix will get you home:

Carefully line up the pin you want to remove in the chain tool.  (If it’s slightly off you risk damaging the chain and bending tool.)  Slowly turn the tool clockwise until it pushes the pin through the rollers, but not past the outer plate.  Remove the damaged link.  If you don’t have a spare link, you can re-connect the ends of the chain.  It will be a little shorter, so take it easy for the remainder of the ride and stay in the smaller chainrings / cogs.  Set the reconnected link into the tool and push the pin back to it’s original position, leaving equal amounts of the pin on either side of the plates.  Note :   to repair a Shimano chain,  you need a special connecting pin.

Replace a chain with a  Masterlink. 

SRAM chains have a Powerlink, a master link with two outer plates, each with one rivet.

To remove :  release tension on the chain, then lift it off the chainring.  Pinch the Powerlink’s plates together with your thumb and forefinger, then slide the plates toward each other with your other hand.

To install :  with one plate facing away from the bike, the other towards the bike, overlap both plates and engage the rivets in the big holes.  Pull the ends of the chain to snap the rivets into the small holes.