The BLS train line serves the main valley villages reliably, and regional PostBus services reach the smaller settlements and side valleys. If you are staying in Lenk or Zweisimmen, the local bus network is adequate for reaching most trailheads and the ski area. A Swiss Travel Pass or regional day pass covers all of these.
A car is useful if you want to explore the side valleys — particularly the road toward the Jaunpass and the hamlets above Boltigen — without waiting for PostBus schedules. Parking at trailheads is generally free and plentiful.
Cycling is practical on the valley floor between villages, and the Simme riverside path is easy riding for most of its length. The valley's steep flanks are for mountain biking rather than road cycling; the gradients on the lateral roads are severe.
In Lenk, the ski area lift passes cover the gondolas and chair lifts across the ski domain; summer hiking passes are available at the valley station for those who want a mechanical assist on the ascent.