The Roller coaster is a fast wide single track starting from the Cnoc Dubh ( pronounced Nock Doo ).  Cnoc Dubh being the high point just North/West of the Burn o Vat on the B9119.  The tracks are steep in places with ascents and descents, the Roller Coaster is Just as its name says, its up and down like a roller coaster, but most of this trail is not on an Os map,  This trail can be done on an evening or on a day out as it all depends on what you add on before or after the Roller coaster. You can add on the Willows area, Burn O Vat, Loch Kinord, Loch Head, you are best to pop into Cyclehighlands and ask for advice.