The hike up from the cottage is a serious ballache, or it was for me. Close to 500m vert ascent IIRC, and it’s too steep to really push the bike for a large part. And the descent off the other side isn’t even that special.
But you still have to do it. Part and parcel of what is an epic ride, ye cannae be mincing round the Lochside and say you’ve done the Ben Alder circuit.
Once up the Breabag, you’re handy for a wee walk up to the summit of Beinn Bheoil if you fancy it. The views must be superb – we didn’t bother with it because the mist was down.