>>1520420Most bmx freewheels have some sort of interface for installation/removal. On the left on in the pic, it's the four notches. Some cheaper ones like the one on the right have no notches or splines, so you usually have to destroy it to take it off. I guess it's not TECHNICALLY destroying it, but it's just a pain to put back together.
With a pin spanner, you'd remove the lockring, usually turning clockwise. Then the outer portion of the freewheel, the teeth essentially, and the bearings and pawls can all come off, leaving just the inner portion still threaded onto the hub. Then you can clamp that in a vise and thread it off of the hub.
Usually 15-tooth and smaller freewheels are going to have the smaller "metric" threading, so you may only be able to go down to a 16-tooth.
