Bottom Bracket Removal
The Bottom Bracket is not really a bracket that is on your bike, but it does hold some weight including the seatpost tube plus taking the load when rotating the cranks when pedalling. There are three common types of bottom brackets, a cartridge unit which is unserviceable, and an adjustable type. The adjustable type contain four major pieces: the locking ring, adjusting cup, spindle, and fixed cup (Photo 1). The third common type is a one piece unit thats complete from the left pedal to the right pedal. These types can be found on BMX bikes. In this article we will be looking at the adjustable type as seen in (Photo 1). The fixed cup is not shown.
Article by Crank
Exploded view of an adjustable bottom bracket. (Photo 1)
To do this kind of job you need some tools. I have used the ones in photo 2. I did discover later that the locking nut tool, which is the one with the blue handle did not fit too well, so I photographed it and used it in this article to show where it is to be used and also to give you an idea what one looks like.
Tools required for removing the bottom bracket. (Photo 2)
The first thing you need to do is to remove the locking adjustable ring with a similiar tool as shown in photo 3. I was sort of lucky because since the tool I used did not fit the locking ring, it came loose by hitting it with a small hammer on the corner of the notches.
How the locking ring tool should be used. (Photo 3)
When the locking ring is removed you then use the splined socket, which is the smaller tool in photo 2. The thing to make sure of here is that where the socket fits into the small splines of the bottom bracket you have cleaned it of sand and grease so that the tool will make a good connection and wont slip. (Photo 4 and 5).
Make sure that the splines are clean of grease and sand. (Photo 4)
Using splined socket to undo the adjusting cup. (Photo 5)
After you have removed the adjusting cup there will be two ball bearing races, and two rubber rings and the spindle. The fixed cup will remain as seen in photo 1. If you need to get the fixed cup out on the other side just use the splined socket and do the same as above. There will not be a locking ring.
To adjust up loose play in this style of bottom bracket, loosen the locking ring as shown in Photo 3, and using the splined socket as shown in Photo 5, slowly adjust the adjusting cup so that any free play is removed. This type of bottom bracket can also be replaced with a sealed cartridge type as shown in the photograph below.
Sealed cartridge type bottom bracket. (Photo 6)
