I recently did a post about measuring chain "stretch" and found my son's drivetrain was indeed worn. This Saturday I was finally was near a local bike shop during open hours to pick up the needed tools.
Because the part needing replacement is the freewheel I needed to get a special tool. When choosing the tool you will need to know the brand freewheel and the number of splines inside (grab a flashlight, look down into the slot, and count). In our case, the freewheel was made by Shimano and has 12 splines. So we picked up a
FR-1 from Park Tools. If you are not sure which tool you need, go to
this page on Sheldon's site or take your wheel to the bike shop and they will tell which you need.
The FR-1 fits into the freewheel and using a big 1" wrench turn it counterclockwise. In theory. Because it is self tightening, it is very difficult to turn. The longer the wrench, the better the chances of getting it loose. Ours was not budging.
Just I was headed out to the garage to look for a "cheater bar" (another tool added to the end of the original wrench to lengthen it), I remembered another trick I had recently heard. If you mount the FR-1 into a vise, you can use the wheel itself to loosen it.
First step is drop in the tool. Then put the nut or quick-release back on the wheel. This holds the tool on for you (a good idea when using a wrench also).
Next mount the tool in the vise TIGHTLY. Grab the wheel and twist counterclockwise. With enough struggle, it will come loose.
Once it was loosened, it easily came off with a lot of turning.
The install of the new freewheel is much easier. Simply spin it on finger tight. The pedaling motion will tighten it to the "correct" torque.
The old freewheel is clearly worn. Most areas between the teeth are no longer perfect half circles as a new one would. This is great time to replace the chain and front chainring also as they will also be worn too.
We will be paying more attention to keeping it lubricated and checking the chain in the future.
