Let me show you the ropes

Double unders are a pesky but very conquerable movement that comes up a lot in CrossFit. Like everything we do there are some specific form elements that will help us with our double unders, whether it be getting our first one or learning to efficiently link them together in a workout. We want to make sure we are jumping from our toes, eliminating any tucking or piking with the feet and legs, and that we are spinning from our lower arms and keeping our arm or wrist circle tight to our body. This will allow us to get good rope speed which is essential to our dub conquering. Keeping our core position tight will help us maintain a good tight hop without doing a dance around the box. Lastly, we want to be relaxed in our shoulders and remember to BREATH, helping keep our shoulders and lungs from totally burning out.
Here is a great video of the double under master Chris Spealler with some good visuals of the above cues and more.
Equipment can also help be a big help. Most of us coaches use a Revolution Rope. Easy way to get one is on the site for Again Faster. There is both the X and the regular Rev Rope, be careful to note that the X is not supposed to be used on pavement.
When choosing the right length for your rope, whether one at the gym or cutting your own Rev Rope, be sure to test it out first. A rope that comes up to about the bottom of the arm pits is a good start since this will allow us to keep tension on the line and create rope speed. But try it out, some people like different relative lengths than others.
Lastly, like anything we do in CrossFit (or lets be honest, in life in general) the only way to truly master double unders is to WORK ON THEM. They are the easiest movement in CrossFit to practice. You will be pleasantly shocked at how much progress you will make with only a few minutes of practice a day. Best thing about them is you can work on double unders almost every day without getting sore, and you can do it almost anywhere (do I smell a most random public area double under pic/video contest??). Get to the box a few minutes early, or stay a few minutes after, and get to work on those ropes!

TEST
max consecutive double unders

WOD
“The Bear”
5 rounds of 7 sets of the sequence:
– Power Clean
– Front Squat
– Push Press
– Back Squat
– Push Press

During a set you may not rest at the bottom only in the rack or the hang.  Hands should never leave the bar.
Rest as much time as needed between rounds,  post loads (not time).