I'd certainly be interested in looking for stuff beyond Chalet-a-Gobet. I had a couple of rides up there while the ground was frozen in January (because it was too cold for road-riding) and that was a lot of fun - riding through patches of snow and avoiding the ice made it much more challenging than it usually is. The other place close to Lausanne that I've found is the Venoge river. Start virtually at the lake and head upstream. There are some short sections that I consider unrideable, but also some fairly decent single-track without any significant elevation changes. If you have a good map then you may be able to string together a reasonable-length ride up the river.