Schwinn sprockets operate like any other brand of bicycles. The main difference in terms of repair and replacement will be seen in the type of sprocket your Schwinn is equipped with: either a freewheel or a cassette sprocket. Regardless of type, with the proper tools and a little bit of patience, replacing a sprocket is a relatively easy task. Plus, doing the work yourself can save you time and money from having to take it to a bike shop.
Cassette Sprocket Replacement
Lay out the tools required in an organized manner so that they are easily accessible. Make sure you have a cassette lock-ring tool, a chain whip and an adjustable spanner that is capable of opening to 16mm. Purchase these items if you do not already have them. The cassette lock-ring tool and the chain whip are unique to bicycle maintenance only, and as such must be purchased from a bike shop.
Remove your rear wheel from your bike by loosening the bolts with an adjustable wrench and sliding the wheel apart from the frame. Remove the quick-release from the axle of the wheel by simply sliding it out.
Insert the cassette lock-ring tool into the lock ring, which is on the opposite side of the actual cassette--the non-drive side. The patterns within some lock rings will vary from bicycle to bicycle; make sure your lock-ring tool is compatible with your Schwinn's lock ring.
Open your adjustable spanner and squeeze its jaws around the cassette lock-ring tool. With your left hand, place the chain portion of the chain whip around one of the sprockets in the cassette. This will prevent the cassette from rotating in the same direction as the lock ring.
Push down with both tools and use as much force as you can muster to loosen the lock ring and cassette. Cassettes have a tendency to be extremely tight and will require significant strength to loosen them.
Slide the old sprocket cassette off of the freewheel body. Replace the new cassette by sliding it onto the freewheel body and then simply reversing steps one through four.
Freewheel Sprocket Replacement
Purchase a freewheel puller that is compatible to the splines on the interior of your sprocket freewheel. Many freewheels follow a standardized Shimano pattern; however, some brands will vary, so match the tool to the freewheel before purchasing it. A bike shop will commonly be able to assist you with this purchase.
Use the freewheel puller to extract the freewheel from the hub by first matching the splines of the tool to those within the interior of the freewheel.
Place the freewheel puller into a vise while the puller is inserted into the freewheel itself. Twist the wheel while it is in the vise to loosen the freewheel from the wheel's hub. Simply unscrew the freewheel once you have loosened it.
Purchase a new freewheel and attach it to the hub by simply screwing it into place with your hands. The freewheel will tighten automatically as your ride your Schwinn bike.