Quote:
Originally Posted by montesa_vr
In theory, I believe it is possible to get an accurate weight one wheel at a time. In practice, the numbers are so variable that they are useless. Besides the problem that 5050 points out of the scale changing height with weight on it, there's the quality of the scales. I have never seen a bathroom scale, digital or analog, that I can't get to show varying weights depending on how I stand. Furthermore, my weight varies as much as 15 pounds from one bathroom scale to another.

As in any measurements, the devil is in the details. Just because you can't perform the experiment, doesn't mean that it can't be done.
My bathroom scales (Healthometer Digital Lithium Scale HDL114) give me the same reading (pounds or kilos) to a tenth of pound, no matter how many times I stand on it or how I stand on it (within reason). Whenever I go to my doctor for a physical (twice a year), I weigh myself on my scales before I leave and she weighs me on her's, which she claims are calibrated. The weights never vary by more than a pound. I weigh about 200lbs
, so I know that my scales accuracy is in the neighborhood of about 1%, which happens to be the claimed accuracy for these scales. The scales are exactly 1.5" high, which just happens to be the thickness of a 2x4. So I run the bike up on the scales on one wheel and a 2x4 on the other and measure each wheel. The sum of the two readings will equal the weight of the bike to within 1%.