This is a copy of the Inside Ride Emachine Free Motion Floating rollers. It looks pretty DANGEROUS xD, it looks like if you go one inch too far to one of the sides you could fall pretty violently, as in “dude, where’s my face?”
A few years ago I was looking for a way to do something like this, I wanted to use my bike indoors during the winter, and during the summer and that stupidly high humidity this place has to offer…
Go to http://www.instructables.com/id/DIY-Free-Motion-Cycling-Rollers for more info.
If somebody comes up with a safer machine let me know 
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Follow my madness!