What Kind of Legroom Does a Cross Support Leave You?

As a short guy, I often wished I was taller for a variety of reasons. The extra height would have come in handy while playing sports. More often, I found myself wanting for that extra couple inches to reach something on the top shelf.

As the saying goes, necessity is the mother of all invention. We, short people, have developed methods and tools that help us work through each day’s hurdles. Step stools, standing on your tippy-toes, or using extension arms are only some examples of items in our toolbox.

Of course, there are advantages to being height challenged. Running through a forest is easy; items on the lowest shelf are no problem for us; we usually do not have to worry about banging our legs on a cross support attached to an adjustable height desk.

Recently, a customer asked us about the anti-wobble cross support, which is standard on our Bonita ET and Eficiente LT desks and optional with our Elegante XT desks. He asked, “does the cross support reduce legroom under an adjustable height table such as RightAngle’s Bonita table?

Legroom under a Bonita table

The simple answer to the question is easy: unless a person is very tall, there is no hindrance under our Bonita table. The stabilizing cross support is mounted high enough where you can stretch your legs out underneath your work surface and not touch the knee-knocker.

For other tables, though, it depends. This answer is not a cop-out. In this article, we are going to talk about table design, stability, and cross support and their relationship with legroom under a standing desk.

What is curious about the question is the sudden concern about legroom. Sit to stand desks are relatively new, but traditional desks have long used modesty panels. I am uncertain if there is an answer, but it would be interesting to find out the source of these new concerns.

When a Tall Person Bumps Their Head, a Short Person Smiles

Tall people have their unique set of hurdles to overcome, such as squeezing into a small car and avoiding low ceilings. When recounting all the issues people of above average height have to cope with, how often do they consider the amount of legroom under a desk?

The location of the legs under the table determines whether the cross beam gets in the way of your legs. There is no standard location for the legs of a table. If legroom is a concern for you, pay attention to the design of the adjustable height desk. As we discuss later, there is a considerable difference in legroom between T- and L-shaped legs.

Is a Cross Support Necessary?

Some manufacturers believe anti-wobble cross supports are not necessary because of how they designed their sit to stand tables. Regardless of design, standing desks without an anti-wobble cross support wobble in their highest position. Standing desks at their highest point that have anti-wobble cross support eliminate up to 99% of the movement.

Why the wobble? To answer this, we need some basic physics.

Stability

Three factors determine an object’s stability:

  1. Center of gravity: the point of an object around which its weight is evenly distributed or balanced
  2. Mass: the size of an object. In this case, the entire standing desk.
  3. Size of the Base: the more significant the base, the more stable it becomes
Approximate Locations of the Center of Gravity on a Standing Table for Three Positions

Let’s apply these factors to an adjustable height desk.

  1. Center of Gravity: the center of gravity for a standing table remains low when set to its lowest position. The low center of gravity results in a very stable surface.
  2. Mass: the legs of sit to stand desks are either aluminum or steel. The most substantial piece of an adjustable height desk is the work surface, made from particle board. In short, most of these units are top-heavy.
  3. Size of the Base: almost all standing desk manufacturers use tables with long feet. These feet run perpendicular to the tabletop.

Of these three factors, the center of gravity plays the most crucial role in stability. When raising the table, the center of gravity changes as well — it moves higher with the work surface. The further it moves from the floor, the more the sit to stand desk wobbles.

Table Design

In his article, Top 3 Reasons for Standing Desk Wobble, Bill Knighton addresses the importance the design of a table has on stability.

A table’s stability is rooted in its design. Height adjustable desks have two basic configurations or shapes. Figure 1 shows the Upside Down U. Figure 2 shows the Cross Support design.

Wobbling without a cross support

Upside Down U

This Upside Down U has a cross support bolted to the legs directly under the work surface, which creates the upside-down “U” (Figure 1). The U-style wobble prevention can only be done on the work surface. The higher you raise the table, the more movement there is in the leg.

Think of a flagpole in the wind: at the bottom there is not much movement. But, at the top, the pole sways back and forth.

That’s what happens to a standing desk that only has an under work surface cross support. Also with this U design, every screw needs to be very tight.

What is the benefit of the U-style base if it doesn’t eliminate table wobble? Some companies say one advantage is the knee clearance and in the same breath say that the cross support design is a knee-knocker.

However, I believe that companies express those sentiments because U-style designs tables are easier on inventory control and packaging. A unique quality of the U-style designs is that the under work surface cross brace expands. This means that one brace extends to fit multiple work surfaces.

Since many of these U-style designs are manufactured in China, importing these tables is challenging. Most Chinese companies offer two braces with different extension ranges.

Cross Support Design

Knighton writes that the shape of the table is not the only other factor in eliminating instability. The other element is bracing. Concentric bracing consists of installing two diagonal braces within a frame. A rigid frame, or truss, results when you attach the ends of the bracing.

Concentric Bracing | Cross Support Reduces Leg Length

This form of bracing increases the object’s ability to withstand lateral loads.

The placement of the cross support minimizes any wiggle occurring while raising the work surface. The design aims to eliminate lateral movement, thus creating a wobble-free desk in any height position. Unlike the U-style, the cross support design is built for a specific sized work surface.

Another benefit of installing anti-wobble cross support to a standing desk is its effect on the legs of the table. The cross support shortens the effective length of the legs and forces the legs to remain parallel.

Crossbeam Interference

Have you ever assembled an entertainment center? If so, do you remember one of the final steps involving cardboard? Although flimsy, after nailing it to the backside of the unit, you discover the cardboard stabilized the entertainment center. The anti-wobble cross support does the same thing for the stability of a desk.

But, do the knee-knockers interfere with leg clearance? In Top 3 Reasons for Standing Desk Wobble, Knighton addresses this exact question.

T-Shaped & L-Shaped Legs

Some competitors say that the cross support decreases the amount of knee clearance on the table, which makes it difficult to sit comfortably. That statement is true if desk has a T-Shaped leg and foot. The T-shape limits the amount of knee clearance when adding a cross support since the legs are in the middle of the table.

However, Knighton writes that tables with an L-Shaped leg and foot are designed to ensure there is a sufficient amount of knee clearance, especially when adding a stabilizing crossbar for support. You see that with this shape, the leg is attached further back on the table giving more room for the user’s knees than in the T-shape.

Posture’s Role

The design of the table using a crossbar is essential, yet there is another factor to consider: the way you sit. Posture may seem obvious, but the roles it plays regarding legroom is often overlooked.

Seating Posture

Personally, I try my best to adjust to proper posture during the day. I have to admit, though, a majority of the time, I lean to one side while writing and slouch when editing. Remember, I am 5’6″, so when I slump in my chair sitting at the keyboard, my feet barely reach the cross support.

If a person, say, Bill Knighton, who is 6’5″, sits at a desk with L-Shaped legs, the cross support is within his reach. And, because of his long legs, he uses the stability cross support as a footrest. When Bill sits with good posture, he has plenty of legroom, and the knee-knocker does not interfere with his work day.

According to this calculator, over 82% of the US population fall between the heights of Bill and I. According to the Centers for Disease Control (CDC), the average height for a woman is 5’4,” and a man is 5’9″. Based on these averages, a stabilizing cross support installed on a table using L-Shaped legs does not interfere with legroom (for most people).

In Sum

There are many factors involved that determine the effect anti-wobble cross support has on a standing table and legroom.

When the height of your work surface is low, then so is the table’s center of gravity resulting in a stable, adjustable height table. The higher the surface of the table goes, the higher the center of gravity, resulting in a table with a wobble.

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David Manney

David Manney

Able to share what I've learned, regardless of complexity, in a clear, concise way. We never stop learning!

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