... and measure the proper height for the desk.

It took me a bit to figure out how high to make the desk.  I looked at my existing desks and office chairs and found that I usually have the height of the chair set so that the lowest point of my elbow is a couple of centimeters (about an inch) above the top of the desk.

In combination with the exercise bicycle, the procedure looks like this:

1. Adjust the exercise bicycle do that it is comfortable to "ride."
2. Sit on the saddle, and sit straight up.  Back straight, proper posture for desk work.
3. Bend your arm so that the lower arm is parallel to the floor.
4. Measure the height from the floor to the lowest point of the elbow.
5. Subtract four centimeters from that height.  Two centimeters is so that the desktop is a little below your elbow, and another two centimeters so that you will be on the "safe side" when you build the desk.  You can always raise the desk with the adjustable feet, but making it shorter means tearing it all apart.

I measured about 115 centimeters from floor to elbow when seated on my exercise bike.  That works out to a desktop height of 113 centimeters. The desk top ended up at about 112 centimeters.  I guess I could raise it a bit, but it is comfortable enough as is.

Calculate the length of the legs by subtracting the thickness of the desktop from the calculated desk height, then subtract the minimum height of the feet.

In my case that should have been:

• 115 cm elbow height - 2cm =
• 113 cm desktop - 2 cm =
• 111 cm desktop height with adjustment "slack"
• 111 cm desktop - 4cm countertop thickness =
• 107 cm bottom of the desktop - 4.5cm minimum foot height =
• 102.5 cm leg length

I ended up with legs 103.5 cm long.  I have no idea what I calculated wrong or which wrong value I might have used. I built the desk in the throes of an allergy attack - sneezing, cursing, and cutting wood by turns.  Anything is possible.

At any rate, it worked out alright.

At a regular desk in a regular office chair, the seat height is critical for me.  A change of as little as 5 mm can be the difference between a pleasant work day and a literal pain.

It seems to be less critical with the "Exer-desk" - probably because I don't sit still long enough for any one set of back muscles to be over-strained.

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"On your bicycle, spaceman!" is a reference to A. Bertam Chandler's "John Grimes" novels and stories. The stories follow John Grimes from his graduation from a (space) naval academy from the Earth through his promotion to commander, and eventually being chased out of service and becoming the Admiral of the fleet for the Rimworlds - planets at the far edge of the galaxy, about as far from Earth as you can get.

"On your bicycle, spaceman!" is used in one of the short stories (it is certainly in The Sleeping Beauty) from The Hard Way Up.  It is used as a parting line between spacers.  It is partially just an example of the jargon that develops between people in military service, and partially a reference (in universe) to the requirement for all ship crewmen to stay in shape by exercising  in the ship's gymnasium - which, naturally, includes exercise bicycles.