With double unders, you're looking for optimum speed and efficiency. The idea is to get the rope turning around your body with as little effort as possible with maximum rope control. A jump rope that is too long will be sloppy and take too much effort to turn.
To get the rope length "just right" for double unders, we recommend rope lengths as determined by the clearance of the rope over your head when jumping.
- The optimum length for double unders is 6" to 10" over your head.
This can be determined by jumping in front of a mirror, or having someone watch while you jump. Simply size the rope down until it is in that range. Make sure that your hands are in a proper position by your sides, and slightly in front of your hips (as opposed to spread out wide).
It is typical to walk into a CrossFit gym and see people doing double unders with ropes that are 12" to 36 " over their heads, which is much too long! These athletes are sacrificing speed, and are working harder than they need to.
Try sizing your rope down into this 6" to 10" range (even if it is uncomfortable at first) and see your double under scores improve!