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:
Adjust the exercise bicycle do that it is comfortable to "ride."
Sit on the saddle, and sit straight up. Back straight, proper posture for desk work.
Bend your arm so that the lower arm is parallel to the floor.
Measure the height from the floor to the lowest point of the elbow.
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.
"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.
The "Refresh Work-From-Home Life" thing just happened to mesh with something I'd done anyway.
This is not the most involved or intricate project, but it fits the concept.
This project is in truth rather simple, and it was rather crudely carried out. I'm not a carpenter, I'm just a guy with some hand tools, time, and an idea (or two.) It turns out that combination is enough to make some useful things.
My "Exer-desk" is helping me get some exercise and improve my health. Its useis only possible because of the peculiar set of conditions that have conspired to let (read: "forced") me (and many others) to work from home.
I've decided to enter this project in the challenge.
It isn't an Earth-shatteringly new idea. It isn't especially clever. It is just a combination of some existing things in useful way.
Before I set out to write this up, I did a quick Google search and found that I could have bought a combined desk and exercise bike. I could have saved myself the trouble, and just bought one.
I didn't, and hadn't even thought to consider it when I set out to build my desk. I made something for myself that somebody else happens to already produce and sell. So it goes.
I do hope that my project will give others ideas. Maybe someone will manage to couple the exercise bike to a generator to charge a laptop battery (or provide power to the TV.) Maybe someone else will make a nice looking "Exer-desk" instead of the industrial ugly one I came up with.
Even if all it does is to encourage someone to buy and use a commercially made desk and exercise bike rig, that's still a win. Any exercise is better than none.
When I built the "Exer-desk", I had several things to juggle.
The desk needed to be high enough for the exercise bike to fit under.
The desk needed to be at the right height for me to comfortably type while sitting on the bike saddle.
The desk needed to be at the right height so that the monitors end up in a comfortable position.
The desk (and the bike) needed to be low enough for me to not bump my head on the (low) ceiling in my attic office.
The desk needed to be (somewhat) level despite any variation in length of the (hand cut) legs.
Given all of those variables, I decided the only thing to do was to make the desk with adjustable feet.
I measured things out and calculated what I thought would be the correct length, then made the feet with an adjustable range of just less than four inches (10 centimeters.)
As it turned out, the legs are almost perfectly the same length and the lowest end of the adjustment is the perfect height. If I'd have known I was that good, I could have just made them the right length and been done with it. Oh, well.
On the off chance that someone else may need to build adjustable feet for a desk or table, here's how I made mine.
I am often accused of buying stuff for my projects rather than using what I've got.
I do try to use what I have, but sometimes the things you need aren't the things you have.
In this case, there was a bit of both. I had some things I could use, and had to buy some other things.
These are the things I collected to build the "Exer-desk":
There's a piece of kitchen counter top there supporting the other bits and pieces.
There's several "not 2x4s" that I had in the garage - left overs from previous projects. They are "not 2x4s" because I'm in Germany. Those pieces of lumber are a bit thicker and wider than the 2x4s I grew up with as an American kid. They are some metric size - I neither know nor care what size. I use 'em like 2x4s, and they do the job. I made the desk legs from them.
There's two packages of screws there. 150 screws, to be exact. I used danged near all of them. That's one of those "you have to have the right part" things. They have to have the right diameter to hold well in the pressed wood chip counter top, and they need to be long enough but not so long as to come out the top of the counter top when you put them in from the bottom. I have loads of screws in the garage - and none them the correct size or length.
There's a stack of 16 angle brackets. I used them to attach the legs to the counter top. I had a few brackets, but no where near enough for this job so I bought a whole bunch of identical ones.
There are four rubber feet in there as well. There's a (rather long) story to how those fit in that I'll explain in another log.
I bought a switched outlet strip to install under the desk. I like to turn things OFF when I'm not using them. That outlet strip is one of the rare ones that has the cord and the switch at different ends. The cord goes out the back way, and the switch is up front under the desktop where I can easily reach it.
There's a roll of iron-on edging for the counter top to cover the rough edges where it was cut. It looks like a roll of duct-tape. I haven't put it on the desk yet. I suppose I really ought to - it cost near as much as the counter top itself did.
I only bought what I had to, but this time around that turned out to be everything but the legs.