ooh ooh I know this one.  It's 118mm (by 68).  You need the extra length because of the chainstay width.
Enjoy the Sterling - mine is nearly completed.
ians
Thanks Ian.  Now I can go buy my drivetrain bits.... 

If you have pic of your Sterling I'd love to see how it turned out.  I'm going to use a fork off my old MTB for the winter and want to get something new and squishy for  the spring 2009 season.  I don't love Rockshox so I'm thinking a Fox Talas 140 RLC - which can be run in 100m travel mode.