Take the path up the Lairig Eilde, soon crossing and a while later re-crossing the burn. Stob Coire Sgreamhach and its offshoot spur Sron na Lairig look increasingly impressive as you approach them up the glen.
From a cairn marking the high point of the Lairig Eilde go roughly west-southwest over boggy, lumpy ground. Trend left to climb into a shallow grassy corrie that leads steeply to a col between Stob Coire Sgreamhach and an unnamed minor top (spot height 778m). There's a clearer trail for the long fairly gradual climb northwest to Sgreamhach's summit with an airy view over the 'Lost Valley' of Coire Gabhail.
A sharp rocky crest leads down (roughly west) to the Bealach Dearg (unnamed on small scale maps), where there's a possible escape route into the Lost Valley. Now follow the continuation ridge above the Lost Valley Buttresses before a final uphill stretch to the twin tops of Bidean nam Bian; the first is higher. Looking north the ground drops into steep crags, and the southern flank isn't much less precipitous either, giving Bidean a really airy feel.
Keeping safely right of Bidean's summit crags (especially if it's snowy), descend the rubbly north ridge quite steeply to a little col between the parent mountain and Stob Coire nan Lochan. A gentler ridge leads onto the conical summit of the latter. Although it's not officially a Munro, Stob Coire nan Lochan is a fabulous peak in its own right, crowning the north facing cliffs of its eponymous corrie.
Head east to descend the curving ridge bounding the east side of the corrie. It's a sharp blocky arete with some very basic scrambling if done direct; a path avoids what interest there is however. Once level with the upper floor of Coire nan Lochan the crest broadens, its continuation leading out towards the spur of Gearr Aonach. At this point cut left, passing a waterfall in the burn that drains the corrie and then following a well-used path steeply down the lower corrie. Staying east of the burn, the path skirts across the lower slopes of Gearr Aonach to reach the floor of Glen Coe. Cross a footbridge over the River Coe and climb towards the A82. Just before reaching the road go right onto a track (the course of an old road) with cuts out a bit of tarmac walking. Gain the road near Allt na Reigh, beyond which another stretch of the old road can be followed most of the way back to the car park, to save having to walk along the narrow bendy section of the busy A-road.
On the east ridge of Bidean nam Bian© Dan Bailey - UKHillwalking.com, Jan 2009