I've just bought a Specialised Comp Gel saddle ( http://www.gbcycles.co.uk/eshop.asp?wci=product&wce=SASP99CG01 ) and it doesn't quite fit my Roox S4 post as the rails are about 2-3mm too narrowly spaced. As its "sort of" a roadie saddle, are roadie saddles slightly narrower then mtb saddles? At the moment I've just forced it into the clamp and its holding fine but it creaks a little.
Thoughts?
If using it like that is a bad idea can anybody recommend any similar shaped saddles that will fit? I kinda like fit.
Have you tried tightening down the clamp? The rails may pop into place. I think I had a similar problem with a Roox post I use a few years ago and clamping it up pulled it inline
Rail spacing is the same on road and MTB, there can be differences in the diameter of the rails though. IIRC 6.5mm is the 'standard', though some can be 7mm or 8mm which could cause the problem you have.