Breaking a Chain
Firstly you need to determine whether or not your chain has a quick release link. These will look different to all the other links on the chain.
Removing a Chain With a Quick Release Link
There are two types of chain with quick release links, a BMX/single speed chain, and a multi-speed chain.
You're going to need:
- A Set of Pliers
BMX/Single Speed Chain QR Link: These have three parts including two chain pins attached by a link plate, a plate with no pins, and a clip to hold the links together. To disassemble, position one jaw of the pliers on the open end of the clip and the other jaw on the opposite pin. Simply apply pressure until the clip slides off, remove the plate and the pins should fall out. To reassemble, just reverse the instructions by dropping the pins into the holes in the chain, place the plate over the other side. Using the pliers place one jaw on the closed end of the clip and the other jaw on the opposite pin and apply pressure until it pops on.
Multi-Speed Chain QR Link: This type of quick release link only has two parts including a couple of identical plates with a pin and a hole on each. To disassemble, position the jaws of the pliers on opposite sides touching the parts of the plate where the pins are welded, then apply pressure to slide the other pins off the plates on each side. To reassemble, simply locate the chain onto the front and rear sprockets ensuring the chain passes through the derailleurs. Position the chain with the QR link facing upwards and with the wheels on the floor and hands on the brakes, put some weight on the right pedal - the chain link should just click into place.
Removing a Chain Without a Quick Release Link
If you can't see a link that differs from the others, then the chain probably doesn't have a quick release link.
Chain tools have two rows of prongs where the chain sits in order to push out a pin from a link.
To separate a link, unscrew (turn counter-clockwise) the handle enough to place one of the links on the furthest set of prongs from the handle. Screw (turn clockwise) the handle so that the driver touches the pin on the link. Carefully continue to push the link - you should be able to see the pin coming out of the other side. Take care not to push the pin out completely as it is very difficult to get the pin back in (if this happens you'll probably have to replace the chain). If you pay attention to the ease of movement of the pin when moving through the link you should be able to notice a change in amount of force required to turn the handle. If you give the handle half a turn from this point, the pin should be at just the right position to ease the link apart by twisting and pulling.
To reconnect the links, push the inner link into the outer link over the pin - this should click into place. Unwind the tool handle and place the link onto the tool on the furthest set of prongs with the pin facing the handle. Now wind in the handle until the links starts to shown at the other side of the link, take the link off the tool and check that there is equal amounts of pin at each side of the link.
The link will now be in place but probably won't move as freely as the others. Un screw the tool handle and place the link onto the nearest set of prongs to the handle. Turn the handle until it touches the pin, and give the handle a quarter turn. Take the chain off the tool - this should have loosened the link (if not try a further quarter turn).