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In this three-part series Dr. Obrecht explains what makes a jump rope just right from the scientific perspective of a Ph.D. Physicist.  In Part 1 of 3: The Cord, we learn about the variety of jump rope cords, and how careful selection can lead us to a better jumping experience.  In Part 2 of 3: The Size, we learn about how to become efficient in jumping by choosing the proper cord size.  Finally, in Part 3 of 3: The Handle, we learn about the most important part of the jump rope, namely the handle technology that makes your rope turn efficiently.

Dr. Obrecht did his Ph.D. work in Atomic Physics at the University of Colorado at Boulder with Nobel Laureatte Eric Cornell.  He is currently the Vice President of JumpNRope, Ltd.

Part 1 - The Cord

Part 1 of 3: The Cord

I’m constantly surrounded by competitive jumpers.  My business partner, Molly Metz, is a 5-Time World Jump Rope Champion, and the entire JumpNRope staff is composed of champions as well.  Our company conducts trainings on double unders and speed-step jumping— trainings at which we are privileged to meet hundreds of CrossFit jumpers ranging in skill level from “Never got a double under” to “I’m training to be on ESPN”.  If there is one constant across the entire range of skill levels that each jumper looks for in a jump rope, that constant is comfort; every last jumper chooses a jump rope that feels just right to them, no matter how different it may be from others’.

From a high-level view, there really aren’t that many differences between jump ropes, you may think—‘so long as the rope isn’t too long or too heavy, it’s probably going to work well for me’.  This mentality is wrong.  There are several variables that factor strongly into the design of a jump rope- each with its own purpose.  Let’s start with the jump rope’s cord.  The four main variables that one can adjust are the cord’s (1) length, (2) thickness, (3) stiffness, and (4) weight (or more accurately weight per length).  However, since we are discussing the type of cord to use, let’s not consider the length for the time being.  I’ll cover sizing a rope in a later discussion (Part 2 of 3: The Size).  This leaves only thickness, stiffness, and weight.


The stiffness of a jump rope’s cord is a measure of the cord’s ability to adapt to changes – more flexible, means more adaptive.  Note: here I’m speaking about the flexibility of a cord to bend, not stretch.  Finding a cord that bends just enough, but doesn’t stretch is difficult, but achievable (we’ve done it!).  Just as there is a large range of athletic skill in jumping rope, so is there a large need for a jump rope to be adaptive.  Higher-end athletes have great control of the rope as they jump, as well as good jumping form– meaning they rarely need the rope to adapt to mistakes and form adjustments on the fly.  This means that they tend to like stiffer jump rope cord as it provides repeatability in the jump- small changes don’t change the rope’s shape.

Newcomers to jump rope tend to like cords that are more flexible, as flexible cord can accommodate their mistakes and improving jump rope form.  Don’t, however, get caught with the notion that flexible cords are ONLY used by beginning jumpers, as there is ALWAYS room for improvement for athletes jumping rope.  Additionally, training with heavier, flexible cords can be quite advantageous, as it provides just enough resistance to quick jumping, but allows for enough speed in your step that you’re training with fast feet.

  • An example of “stiff” cord is the 1/16″ stainless steel cord used in the uncoated and blue-coated R1: Speed Rope.  This cord has been championed these past five years by JumpNRope and the competitive jump rope world for speed and power events.  Note: the coating on the cord provides a nice barrier to general wear-and-tear.
  • An example of “flexible” cord is either the black coated steel cord used in the coated R1: Speed Rope (used heavily in CrossFit and elite athletic training), the PVC cord used in the R2: Trainer Rope (used for training everywhere by everyone- flexible, but not stretchy), or in the beaded cord of the R3: Beaded Rope (used for warming up and strengthening arms).

The weight of a cord is also, without a doubt, a central factor to deciding upon the right jump rope.  One might think, in fact, that since a heavy rope is more difficult to throw around that, conversely, a lighter rope is always better.  Well, lighter is NOT always better.  Imagine the case in which you jump with a near-weightless rope.  It would be quite difficult to judge by feel whether you should jump or not— you wouldn’t really know where the rope is in relation to your bounding body—weight helps the user gauge the rope’s location.  Additionally, a super-light rope is much less controllable— just a small amount of flicking of the wrist will propel the cord around your body wildly.  Therefore, there’s a trade-off between a light rope and a heavy rope: fast & hard-to-control or slower & stable.  Finding that balance in weight is a jumper’s preference.  A skilled jumper with experience will likely choose a lighter rope, because they have the rhythm of jumping under control, while a beginning jumper will be much better off with a slightly heavier, more stable rope.


Combine this analysis with what we’ve learned from the stiffness of the cord, and we find that a great beginning jumper will likely find success in a slightly heavier cord, with plenty of flexibility, while the more-experienced jumper will prefer either a semi-flexible stainless steel cord or a flexible coated steel.

  • The R1: Speed Rope features either the semi-flexible steel cord or a flexible coated steel cord.  Both ropes are super-fast (used by World Champion jumpers!) and should be considered ‘competition ropes’ to work towards.
  • The R2: Trainer Rope, which features the flexible PVC cord, is slightly heavier than a thin steel cord, and provides a nice stable jump rope for beginners, or a nice fast-paced resistance for higher-end athletes.
  • For a great arm burnout or overall athletic warmup, the R3: Beaded Rope provides weight via 60 colored beads, and is great for a very stable jumping experience.

In Part 2 of this 3 part series, I will discuss the two variables of the jump rope’s cord that we haven’t discussed- the thickness and the length.  This discussion will focus on both the aerodynamics of the cord, along with how to become an efficient jumper by playing with the rope’s length.

…for more information on the different types of jump ropes available, please visit the JumpNRope Jump Rope Selection Guide webpage.

Part 2 - The Size

Part 2 of 3: The Size

In part 1 of this 3 part series, I discussed the different variables of a jump rope’s design and I outlined the key points that one should look for in a jump rope’s cord, namely the cord’s weight and flexibility.  In this part of the series, however, I will focus more on efficiency in jumping, and how to reach a level of jumping at which double unders become a breeze.

Let’s now look at the thickness of the cord.  Most jumpers are not going to truly notice the thickness of the jump rope’s cord unless they’re performing jump rope with high-intensity.  They may notice the fact that thicker ropes are typically heavier than thinner ropes, but you generally won’t notice the aerodynamic drag created by the thickness of the cord.  A good rule of thumb is this: unless you can hear the whistling noise created by the speed of the cord, you’re likely not bumping up against aerodynamic drag as your main challenge in jumping.  Therefore most of us aren’t going to need to factor the aerodynamic cross section of a jump rope cord into our decision-making process when selecting an appropriate rope.


Others, however, like those competing in the CrossFit Games or the World Rope Skipping Championship, are going to be selective with the thickness of the cord.  In the case of reducing aerodynamic drag, thinner is always better, obviously.  What can end up becoming an issue with thinner cords, however, is the durability of the cord, as thinner cords will tend to have a higher risk of bending, breaking, fraying, or any other casualty of jumping rope.  There’s a simple trade-off that comes along with a lower-profile cord, and finding that can be challenging.

  • An example of a durable, low-profile cord is the blue-coated and uncoated stainless steel cord of the R1 Speed Rope.  This rope is used by the fastest jumpers in the world!
  • The absolute fastest jumpers in the world use a very special, lightweight steel cord for speed events.  Though not recommended for the general public, JumpNRope supplies these jumpers with these custom-made R1: Speed Ropes!

Along the lines of efficiency in jumping, comes a discussion on the length of the jump rope’s cord.  When it comes to a jump rope’s length, shorter is typically better, up until that point at which you can’t jump it comfortably anymore.  Short ropes are efficient, as you don’t have as much cord to throw around (weight), and the cord you do throw around doesn’t travel far from the axis of rotation (the centrifugal force that your arms work against).


Efficient jumping comes then from small movements of the wrists and feet controlling a relatively small rope (small being relative to the user’s size).  It may happen from time to time, however, that fatigue has set into your body and your arms aren’t able to control the rope the way that they do when they are fresh.  This is why it is important to be able to adjust the length of your rope (at least a small amount).  Adjustment can come from either tying a knot in your cord (if it is flexible- like PVC), or moving a sizing collar up or down along your steel cord.  The ability to change the rope’s length to adjust for your fatigue level is important to consider in choosing your just right rope.  If you plan to be using your arms a lot in a workout, make sure you allow for a few inches of room in your jump rope’s cord!

  • The R1: Speed Rope can be adjusted with a sizing collar, the R2: Trainer Rope can be adjusted by tying knots in the PVC cord (don’t worry- even World Champions do this!), and the R3: Beaded Rope can be adjusted by just tying knots in the braided cord.
  • For online sizing instructions & video instructions, go to JumpNRope’s sizing pages for the R1 Speed Rope, R2 Trainer Rope, and R3 Beaded Rope.

Putting this all together, the key thing to look for in the dimensions your jump rope’s cord are (1) short, yet comfortable, length, with (2) a thickness of the cord that is commensurate with your skill level—thin profile for skilled jumpers, and (3) the ability to adjust the length of your cord at a moment’s notice!

In Part 3 of this 3 part series, I will be discussing the most critical part to your jump rope’s design, the handle.  A properly-designed handle will facilitate easy jumping and allow for an effortless turn.

…for more information on the different types of jump ropes available, please visit the JumpNRope Jump Rope Selection Guide webpage.

Part 3 - The Handle

Part 3 of 3: The Handle

Until this point, I’ve only mentioned the properties of the jump rope cord that one should consider when selecting the just right jump rope.  However, just as important as the jump rope cord is the jump rope’s handle technology.  The handle is not just a means of holding the cord to your hands; the geometry of the handle greatly affects the efficiency with which you jump, and ultimately results in faster, more-competitive jumping skill.


The most efficient handle system created to date has come from the mind of 5-Time World Jump Rope Champion, and JumpNRope founder, Molly Metz.  With her decades of experience in the competitive jump rope world (28 years), Molly discovered a need for faster, more-efficient jump rope handles, and subsequently invented (and patented) a jump rope handle technology that revolutionized the sport.  She not only added the dual-bearing shaft technology concept to the jump rope handle— a critical component, she also added one of the most important features of a competitive jump rope’s design: the pivoting-ball element, which gives the jump rope cord the ability to pivot at a variable angle from the handle’s rotating central shaft.

The dual-bearing shaft technology allows for a fluid, near-frictionless turn of the rope’s cord as you drive the rope with your hands and wrists.  In fact, JumpNRope has posted a video clip where we show our handle system spinning for 10 seconds from a single, applied spin  The main point of the handle’s bearing technology is that it is fast & smooth and allows the user to put their efforts elsewhere in jumping– not losses to friction in the handle.


The pivoting-ball element also helps a jumper maintain an efficient form due to the fact that it allows the jump rope’s cord to be decoupled from the angle that the hands hold the jump rope’s handles.  This means that a jumper who holds their hands at strange angles (up, down, or both!) can jump a cord that has the same shape as a jumper who holds their hands at normal angles!  The pivoting ball accommodates for this and self-corrects for the jumper’s goofy form!

  • This handle technology has proven so successful over the years that not only is it used by Jump Rope Champions around the world, but Molly has recently been awarded two U.S. Patents for this jump rope technology!  If you see jump ropes with bearings and a pivoting-ball element—this is Molly’s patented invention!


Lastly, it should be stated that the size of the jump rope’s handles can really make a difference with regards to one’s performance in jumping rope.  Elite athletes will tend to like the short, light-weight handles, as the smaller handles not only weigh less, they also allow for a closer, tighter grip— almost contouring to the shape of your hand, providing control and access to greater speeds.  Others, however, will like the length of a longer handle, as the extra length can allow for increased leverage, providing an advantageous boost to the flicking action of the wrists.


  • JumpNRope features both handle lengths in all ropes— the R1: Speed Rope, the R2: Trainer Rope, the R3: Beaded Rope, and our Speed Ball training device.

To put this all together, one should realize that a lot of thought can be put into the choices that you make when choosing a jump rope.  At JumpNRope, we’ve spent years designing (and patenting) high-performance jump ropes that cater to all athletic levels: from elite Jump Rope Champions, to beginning jumpers and kids!  We have a full range of rope types that will allow you to progress your skills in jump rope.

…for more information on the different types of jump ropes available, please visit the JumpNRope Jump Rope Selection Guide webpage.