Fixed Steady from Pipe Flanges?

[Hopefuldave]

Thanks Greg, useful info :)
I hadn't though about a "safety valve" on it - perhaps the "nut" for the closing bolt could be a delrin/ally/crappy-Mazak cylinder with the bolt thread tapped through it, perhaps not full depth, ready to strip threads? Or I could do what I did when I rode a Really Skinny Tyre bike (glued-on tubulars) and set up a scraper to clear the way for the rollers, a bit like a cow-catcher :)