Optimal gaming mouse cable

A good gaming mouse cable has to be good at a couple of things. The four most important factors in my opinion are: flexibility, slickness, low weight and durability.

In the following I will explain why these four attributes are important.

Flexibility

A good gaming mouse cable should not be too rigid or stiff. The reason is simple: a rigid cable does not move easily and thus you have to exert more force to move a mouse with a rigid cable, as compared to a mouse with a flexible cable.

Depending on the direction your cable points to and the direction of your mouse movement you can feel the cables resistance. This can be very distracting while gaming.

With a very light gaming mouse the effects of a rigid cable become more obvious: when you only need a small amount of force to move your very light mouse around, a rigid cable feels much more resistant than if it were on a heavy mouse.

A cable should not be too flexible and limp though. Imagine your mouse with a piece of dental floss attached instead of a cable. The dental floss is so limp that every time you would move your mouse forward the dental floss most likely would get in the way of your mouse. Or put another way: a mouse cable has to be stiff enough so that when you move your mouse forward, the cable moves with it.

Note that most gaming mouse cables are so ridiculously rigid that they will never block your mouse movement. Lack of flexibility is the biggest weakness in most gaming mouse cables.

So how do you make a cable flexible? The two most important factors are the cable jacket and the copper conductors.

Cable jacket materials

When it comes to cable jacket materials there are a bunch to choose from. They all have their advantages and disadvantages.

Take polyvinyl chloride (PVC) for example: PVC jackets in itself would not be very flexible. Which is why plasticizers like phthalates are commonly used to make them softer. The problem with phthalates is that they leach over time, meaning your cable becomes less flexible. Also phthalates could be bad for your health. On Wikipedia it says:

«An endocrine disruptor is a substance that interferes with the normal hormonal mechanisms that allow a biological organism to interact with its environment. In the scientific community, phthalates are broadly classified as endocrine disruptors; while many scientific studies indicate the likelihood that phthalates behave as endocrine disruptors in human beings.»

Next there are fluoropolymer jackets like for example polytetrafluorethylen (PTFE). A PTFE jacket would make for the slickest cable jacket there is. However the flexibility of a PTFE jacket is poor (unless you make them extremely thin-walled, which is hard to do on a gaming mouse cable which by nature has a relatively large diameter).

Fluoropolymers also have the highest densities of all plastics, which would be negligible when being used for the insulation of a copper conductor, but when used for the jacket of a cable it would be significant. PTFE for example has a density of a whopping 2.2 g/cm³. To put things into perspective: that is almost as high as the density of aluminium, which is at 2.7 g/cm³.

Then there is silicone. A silicone jacket would be very flexible. Yet silicone has a tacky surface and is not that great when it comes to durability, which means the wall thickness of a silicone cable jacket has to be higher than with more durable materials; and that increases the overall weight of the cable.

In the search for the optimal gaming mouse jacket material we ended up with a material called polyurethane (PUR). A jacket made of PUR not only can be made very flexible without the use of phthalates.

It also fulfills the other requirements for a good gaming mouse cable: it can be made with a very slick surface that will not drag on your mouse pad.

PUR is also relatively low in weight: the PUR grade we use for our upcoming gaming mouse is at just 1.15 g/cm².

PUR is also extremely durable, which allows you to use a very small wall thickness. And a small wall thickness results not only in less weight, but also in more flexibility, because the higher the wall thickness of any material, the harder it is to bend (this is called geometric stiffness).

Conductor design

As you may know a typical USB cable has four conductors inside. Each of these conductors consists of copper wires that are twisted together (theoretically you could use just a single wire for each conductor, but nobody does that for USB cables).

In a standard gaming mouse cable one conductor consists of seven pretty thick copper wires with a diameter of 0.12 millimeters each.

We have found that when using 19 wires instead of 7 wires, the flexibility of the conductor increases significantly. Think of it this way: bending two wires that together are as thick as one thick wire requires less force than trying to bend that one thick wire.

Obviously when using 19 wires per conductor you have to use smaller wires, or else the conductor would be very big, which would lead to a much bigger and thus heavier cable. For our upcoming gaming mouse one of the 19 wires per conductor will have a diameter of just 0.05 mm.

Second, they make the cable more durable when subjected to bending, something that is called flex life (or quintessentially German: Biegewechselfestigkeit). There is a nice quote from Tecumseh which fits almost too good:

A single twig breaks, but the bundle of twigs is strong.

A word of warning though: every time you bend a cable it will reduce the life expectency of your cable by a tiny bit. Fine copper strands lessen the negative effect bending has, but they do not completely negate it.

When it comes to the insulation around the conductors you want to have a material that is not too stiff and that has high strength and flex-life.

The density of the insulation material is not as important as it is for the jacket, since the insulation is so much smaller than the cable jacket, but a low density if of course always nice to have.

You also do not want a sticky insulation, because that would prevent the four conductors sliding over each other effortlessly.

High Density Polyethylene (HDPE) is a good insulating material, since it is very slick (not quite as slick as PTFE, but almost) and has a very low density of 0.95 g/cm³. Unfortunately HDPE is not the strongest plastic and its flex-life could be better as well. Luckily however the PUR jacket will protect the relatively weak HDPE insulation.

Slickness

The outer surface of a gaming mouse cable needs to be slick, so it will glide over your mouse pad without you noticing it.

For this reason I think that cables with a woven jacket are not optimal. Woven jackets have a rough surface that easily snags on your mouse pad (especially if it is a cloth mouse pad).

With a paracord-style cable you at least have the advantage that you save quite a bit of weight, since the woven paracord is much thinner than a traditional gaming mouse jacket.

A so-called braided gaming mouse cable however ist just stupid: it is a nylon braid over a regular cable jacket. A braided gaming mouse cable is the worst of two worlds: the scratchy feeling of a woven jacket in combination with the high mass of a traditional gaming mouse jacket.

Braided cables will fray over time, which only increases the chances of them snagging on your mouse pad, by the way.

Low weight

A good gaming mouse has to be as light as possible. Thus its cable has to be light as well.

In order to achieve a low cable weight everything has to come together: the conductors have to be very small, and not thick like in a power cord. The insulation around the conductors has to thin. The wires in the electromagnetic shielding has to be thin. And the cable jacket have to be thin as well.

The cable jacket has the largest influence on the overall cable weight. A peculiar dependency by the way is that the the bigger the diameter of the conductors and the electromagnetic shield around the, the bigger the diameter of the outer cable jacket has to be. Meaning: if you use small conductors and a small shield you can save weight twice.

Durability

A cable has to have a certain degree of durability. It does not matter how flexible, slick or light a cable is, when it breaks after only a few months of use.

This makes for a difficult optimization problem: take the flexibility or the weight of a cable for example. One way to achieve a flexible cable is to use a thin jacket. However a thin jacket also results in less durability. And as already mentioned a very thick jacket would be very rigid and very heavy. There is a trade-off between flexibility and durability.

PUR is incredibly durable jacket material when compared to PVC or silicone. Not only is PUR extremely tough, it also has excellent flex life and abrasion resistance. It is also very resistant to water and chemicals, so it can be cleaned easily.

We found out that a PUR jacket is extremely durable the hard way by the way: we had trouble finding a cable stripper that could remove the jacket for the prototypes of our upcoming gaming mouse.

As already mentioned having conductors with lots of fine strands instead of conductors with few and thick strands, also helps with durability. As does a strong insulation over those conductors.

A great way to significantly boost the strength of the cable is to put so-called Kevlar fibers into the middle of it. This is called a filler. Since together with the jacket these Kevlar fibers are the shortest element in the cable, they will take a significant amount of load in the case of a strong pull, protecting the conductors (when the conductors break, your cable is done).

Additionally the Kevlar fibers reduce abrasion between the four conductors.

The downside is that Kevlar is a pain to work with. Just cutting it is difficult, unless you use a very high quality side cutter or even a dedicated pair of Kevlar scissors.

Summary

The optimal gaming mouse cable has finely stranded copper conductors, a thin, lightweight, robust and slick jacket made from PUR and in the middle of it all Kevlar fibers. This way the gaming mouse cable will be light, flexible, slick and robust, all at the same time.