In reply to Pids:
Its a good track all the way to the lodge, so beyond where you'll probably need. In fact, to the top of the main climb you could comfortably do it on almost any bike, gets a little bumpier afterwards but still easy. There's a fair old climb, with one quite steep bit up to Cona Mheallain. For some reason, its always windy at the top of this so even after you summit, you might be working hard still!
Once needed the granny ring on the flat bit in the wind somewhere after that bit, but it was still worth it for the time saving (was in winter) and the very fast ride back down. I do remember both me and my mate getting cramp at exactly the same moment in the back of Maol Lunndaidh's Fuar-Tholl Mor, thanks to how much we'd worked cycling in that time.