Just an update. Still diggin' the SS conversion. I've settled on a 32:18 ratio, which covers 50km gravel grinders and singletrack for me. I've ditched the Surly Singleator (quite possibly the ****tiest piece of hardware I've encountered in the MTB world) for a completely new rear wheel with a White Eno Eccentric hub and Mavic XM17 rim. It's basically worlds better and suits the kwality of the Fat well. Tyre choice on the rigid SS is probably more critical than ever and I'm trying a pair of baggier Schwalbe Racing Ralphs currently (26x2.35").