It is my personal belief that many people own bicycles, and that many of those people aren't interested in riding for pleasure / exercise when it is raining, snowing, dark, etc. outside, and that many of those people would ride their bicycle indoors if they had a fun and challenging device that allowed them to do so, and that many of those people would build such a device themselves if given the encouragement and advice to do so. Thus, if my calculations are correct, this Instructable my indeed be appropriate for, and benefit many people.
DIY Bike Rollers from Jason Sauers on Vimeo.
Some people prefer stands and other types of trainers over rollers, but to me there are a few appealing aspects of rollers vs others:
Faster / more intense Workouts
More challenging / engaging
Better all-over body workout
No adapting or installation - just set the bike on and go
Some may argue that it isn't worth the cost (a new set can be bought ~ $200) and time to build your own, but that can be said about almost anything-
I enjoy building things, I had all the materials that I needed, and it only took a weekend to build.
The building isn't particularly challenging, so long as you are familiar with basic construction / projecting techniques, and have access to the necessary tools and materials.
I would not however suggest this as a first project, or for someone who does not have experience with similar projects.
P.S. I do not intended for this to be a set of step-by-step construction plans, as I feel that those who will likely have success in completing a project like this will be able to easily fill-in the b_a_ks that I may leave.
P.P.S. This is another homebuilt setup (much more sophisticated than mine) that I didn't find until writing this - however for me the free-motion feature isn't very important :