Twenty minutes ago, I had never heard of rail bikes. Now I must have one. Maker of this rail bike and Velospace member Stinky Pete writes, "This is what happnes when a person works nights with too much time to think." I should start working nights if it produces marvels like this.
Link -via Make | More Rail Bikes
Some bikes have been built with flanges on the rims, some "bikes" have even been built with four wheels and the rider in the centre (there was a name for these, but I don't recall it). However fewer have been built with proper conical rims. It's the conical "tyres" that keep rolling stock centred on the tracks, not the flanges. And certainly not a fixed plate.
Railroad companies can be real killjoys.