On bicycles ridden only in dry conditions and/or with fenders, the normal failure mode is a progressive notchiness in the steering, described as "indexing" in the bicycle world, caused by pitting of the races or false brinelling, although the term stems from a misunderstanding of the cause; true brinelling is caused merely by pressing the ball axially into the race, and it is almost impossible to replicate this damage even by striking the fork crown repeatedly with a hammer. The pits are by far deepest at the front and back of the head tube, and are actually caused by flexing of the fork blades, which is transmitted to the steerer tube. This misaligns the bearings and causes fretting, a small amplitude, large stress movement which tears metal from the races at the points where the balls rest.