Luasanne the town itself is flat along the lakeside, but if you want to go anywhere other than along the banks of Lake Geneva you are going to have to climb some steep hills and you won't do it on a 72" gear. You can try but I reckon you will be pushing your bike most of the time. You could cycle south back to Geneva I suppose. The scenery is stunning. Vevey east of Lausanne is nice. really you want to get onto the French side and ride the cols of the Alps, be a real fixed cyclist in the same mould as the early TdF greats.
Why Lausanne anyway, going to clear out your Swiss bank account or make a deposit?