Why not keep the road bike & build up a cheap rigid 29er without compromise, then you can choose your weapon ? I have tried several times to build a flat bar cross type bike but then I find myself putting wider tyres one it & embracing the the extra grip over speed.
I replaced an OO Scandal like this
[/url]IMG_0301 by Martin Robbo[/url], on Flickr[/img]
With the much more spendy Pegasus like this
[/url]IMG_1058 by Martin Robbo[/url], on Flickr[/img]
TBH if I wasn’t a tart I would say the very cheap OO frame was just as light & just as good, but I have to tell you that the Pegasus is better or my head will explode 😉