People + Process = Performance

Product Reviews from Safety 2012: Sit-Stand Keyboard Tray Mechanism

“Sit-Stand” Keyboard Tray Arms

There is much attention being paid to sit-stand workstations in computer office environments across the country.  Recent studies and publications on “sitting disease” have increased employer and employee awareness of the negative effects that result from sitting at a desk all day.  There are a handful of solutions to provide users with the ability to alternate their posture from sitting to standing during the day.   At Safety 2012 there was one office products vendor, Ergo Genesis, that showcased their sit-stand keyboard tray mechanism, the Ergo Fusion Sit-Stand Mechanism.

The company states that this mechanism combined with a monitor arms provides an easy way to obtain a sit-stand workstation.  A closer look is needed to see if this claim is completely accurate.  This sit-stand mechanism has a total height excursion range of just over 14”—the height range measured from the top of the mechanism’s track is 5.88” below and 8.25” above.

A standard height desk is typically 29” or 30” above the floor.  For our purposes we will use 29” as our work surface height.  A standard work surface thickness is 1.25” so that reduces the above height to 7” above the work surface which would then place the top height of the tray at 36” above the floor.  Does 36” match the standing elbow height of the majority of males and females?  Using anthropometic measurements we see the following:

  5th% Female 95th% Male
Standing Elbow Height 37.2” 46.9”
Sitting Elbow Height 21.5” 31.1”
Difference between heights 15.7” 15.8”

Source:  Bodyspace, 2nd Edition, Stephen Pheasant, Taylor and Francis, Ltd., Philadelphia, pg. 178, 2001.

Based upon the above information, this sit-stand mechanism does not provide enough above the surface height range for it to accommodate even the 5th percentile female.  Other sit-stand keyboard tray mechanisms have similar height ranges and similar limitations.

I must mention that it may be possible this mechanism could fit the 5th percentile female using an “open angle” elbow posture (100-110 degrees) and one added factor—the tray would need to be placed in a negative tilt.  This would “raise” the front height of the tray and lower the back height of the tray which may allow it to fit the user.  Of course, one would need to assess the actual person to know if this was true.  However, there are very few 5th percentile females users compared to the rest of the user population.

The keyboard tray mechanism itself was easy to use.  The only knob was used to adjust the tilt angle of the tray.  It was thin and had nothing underneath that would hit a user’s thigh.  Overall, the mechanism is very good, it just does not have the necessary height range to make it a viable sit-stand solution.

In conclusion, one should be cautious in considering the use of sit-stand keyboard mechanisms as a solution to provide sit-stand workstations.  The typical dimensions of users prohibit the use of these mechanisms as a way to achieve proper sit-stand workstations.


Kelby Ergo Design does not endorse any of the products or companies featured in the review. All images are property of the vendor and used for illustrative reference only