Could anyone be able to tell me all the different sizes of bottom brackets and bearing for bmx's as i am currently looking to buy a new bottom bracket set for my bmx, what is ment by (mid bearings?) and it would be awsome if someone could tell me how to fit them and other tips, please, thank you in advance :D
for bmx there are several styles of bottom bracket. Mid and spanish are examples. Each style has a different outer diameter which can be used for different frames (the most popular being mid). There is also a size on bearings, which is always either 19mm, or 22mm. This refers to the inner diameter (where the hole is) and you need the size of the bearings to fit your crank set, which will have either a 19mm spindle, or 22mm. to fit bearings is quite simple. first, remove your cranks. the arms come first, which is done by loosening the pinch bolts (at the opposite end of the pedal) and completely removing the crank bolt, which is the bolt that directly holds the cranks to the arms. after all those bolts are removed, slide of your cranks and sprocket, then get a rubber mallet and smack the side of the spindle till it falls out of the other side. next you need a long, thin and rather blunt object and once again the mallet. poke the thin object through (i use the extension from a socket set) through one side of the crank and knock out the other side bearing carefully. remove the slide spacer from inside, and then do the other bearing. to put new ones in is pretty much the same, but instead of knocking the bearings out, you should grease them up, and press them in slightly, before lightly hammering them into place. then resit the spacer inside, and put your cranks back in. DONE!
