The rounded cams touch the rock, and the stem bar between them is where you clip in. The axlebolt is the circle where they all meet.
圆形的凸轮接触岩石，两个凸轮之间的柄就是手握的地方，轮轴螺丝连接凸轮和手柄。
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If your foot is pulled towards the rear of the bike, you risk running over your own leg, twisting your knee severely or smacking your ankle against the rear axlebolt.
Notice that the axlebolt is higher than where the cams touch the rock. This is what provides the (approximately) 4:1 mechanical advantage that keeps the CAM secure, even in a smooth, parallel crack.