Starting in Pitlochry, Perthshire, the challenging route covers 102 miles to the Cairngorm ski resort, taking in some 8825ft (2690m) of climbing - twice the height of Ben Nevis - over some of the UK's highest roads.
The event, on June 1, gets its formidable sounding name from the three ski resorts that riders will pass: Glenshee, The Lecht and Cairngorm, where it finishes.
While the soaring ascents will test the mettle of participants, they will get their reward in the breathtaking backdrop and dramatic downhill sections. Race organiser Alan Anderson, a comedian and member of Glasgow Triathlon Club, has long believed that route would prove fantastic as a cycling sportive. A keen skier, he knows the roads in the area inside out.
"It passes through some of the most spectacular scenery in the country," he says. "The route is an anti-clockwise circumnavigation of the Cairngorm plateau, so on your left there's the highest mountain range in Britain to gawp at. As well as one of the most remote bike rides, it's among the most glorious."
The course, which features eight eye-wateringly tough categorised climbs, heads north from Pitlochry towards Glenshee, taking in Braemar, The Lecht, Tomintoul, Nethy Bridge to Cairngorm.
"You've got five of the six highest roads in Scotland," says Anderson. "That means that as well as some of the longest climbs, there is also some of the longest descents.
"Particularly the one coming down off The Lecht which is incredibly fast and has a 20% gradient on the A939 Cockbridge to Tomintoul Road - we will be reminding riders to stay within the speed limit of 60mph there.
"After the first climb of the day at Cairnwell Pass, there is around 25 miles downhill. Towards the end of the ride, you have another 20 miles along Strathspey which is nice and flat, providing some recovery time before you turn back onto the access road at Rothiemurchus and climb up to Glenmore then Cairngorm itself."
When he first coined the idea Anderson reckoned it would attract 150 people or so. "We had that many sign up in the first 12 hours alone," he says. "We now have around 400 riders with a provisional limit of 500 places."
Early Bird entry costs £28; £47.50 including coach transfer. For more information, visit 3pistescycle.co.uk