1. The Hebridean Way Cycle Trail, Outer Hebrides
This awesome cycle route stretches for 185 miles from the island of Vatersay in the south to the Butt of Lewis in the north. If you want to cycle the whole trail you'll need to charter boats to take you between the islands, or you can just do shorter sections. Adventure travel company Wilderness Scotland run a six night guided break that includes boat hire, you can find out more here.
2. Burray to Kirkwall, Orkney
This lovely 12-mile route takes you through the Orkney islands of South Ronaldsay, Burray, Glimps Holm, and Lamb Holm, ending up at the Orkney capital of Kirkwall via the Churchill Barriers: A series of four causeways built to link the islands during the second world war. You'll also pass the famous Italian Chapel on Lamb Holm, which was built by Italian prisoners of war in the 1940s.
3. Glen Sligachan Trail, Isle of Skye
This stunning but tough 27-mile mountain bike route starts and finishes at the Sligachan Hotel in Skye, so at least you know you'll have somewhere to get a hot shower at the end of the day. The trail takes you right through the heart of beautiful Glen Sligachan, past Loch Scavaig, and the beautiful mountains Marsco and Bla Bheinn, part of Skye's Red Cuillin mountain range.
4. The Southern Borders Loop, Scottish Borders
This picturesque road circuit in the Scottish Borders features two different route options: A shorter, relatively flat 50-mile loop that can be completed in a day, and a longer, steeper 75-mile route with five big hills that can be broken up with an overnight stay in the pretty Borders town of Hawick. Both routes take you through gorgeous rolling countryside, forests, and open moorland.
5. The Torridon Circuit, Northwest Highlands
The Torridon Circuit is a tough but rewarding 28-mile mountain bike trail. It's mostly off-road, and you might have to carry your bike at times. However, the grandiose scenery, filled with mountains and sea lochs, more than makes up for the challenging, 900-metre climb. The route starts and ends at the Torridon Inn, so you can celebrate with a well-earned pint.
6. Lerwick to Scalloway, Shetland
This scenic, six-mile chunk of Shetland's cycle network is perfect for road bikes, and takes you from Shetland’s "capital" town of Lerwick to the pretty, historic village of Scalloway, with its picturesque ruined castle. The route passes hills and wild moorland and includes panoramic views of Scalloway, the sea, and the many islands that lie to the south and west of the town.
7. The Loch Rannoch Circular, Perthshire
This beautiful trail runs for 23 miles around the shore of Loch Rannoch near Glencoe. It's suitable for all types of bike as the path around the loch is smooth and largely flat. The loch is particularly beautiful in autumn, when the surrounding trees turn gorgeous shades of gold. If you don't have a way to transport your bike there, you can hire one at Loch Rannoch Marina.
8. Rothiemurcus and Lairig Ghru Circular, Cairngorms
This whole part of the Cairngorms is a haven for mountain bikers, but this circular 30-mile ride starting at Bothy Bikes is particularly impressive as it has an optional detour via the spectacular Lairig Ghru pass. It's also not too difficult as it only climbs 600m, unlike other trails in the area that ascend as high as 1700m. You'll still need to be pretty fit though.
9. Assynt Achiltibuie Circular, Northwest Highlands
For a longer on-road challenge, you can't beat this 70-mile long Achiltibuie route, which follows some of Assynt's spectacular coastline before heading inland on single-track roads. The route also takes you past the famous Lochinver Larder, which is a great place to grab some lunch (they do amazing pies) before continuing on to Loch Assynt and the ruin of Ardvreck Castle.
10. Gairloch and Loch Maree, Wester Ross
This incredible loch in the Highlands is filled with sixty scattered, densely forested islands which represent one of the last remaining pockets of ancient woodland in Britain. This 17-mile mountain bike route takes you from Slattadale Forest to the sandy beaches of Gairloch via Loch Maree, ending at The Old Inn. H+I Adventures also run a longer coast-to-coast trip that takes in Loch Maree.
11. The Ayrshire Coast Cycleway, Ayrshire and Arran
This straightforward, flat, 19-mile long linear route is perfect for road bikes, and also features spectacular views of the Isle of Arran. It takes in long stretches of the Ayrshire coastline between Irvine, Troon, Prestwick, and Ayr, and it's close enough to Glasgow to make an ideal day trip (you can take bikes on the train to the starting points at Irvine or Ayr).
12. 4 Abbeys Cycle Route, Scottish Borders
This historic, incredibly pretty, and relatively easy route is a 55-mile circular trail linking the four main abbeys in the Scottish Borders: Melrose, Dryburgh, Kelso, and Jedburgh (pictured). It mainly follows quiet roads, so it's fine for any type of bike. There are a couple of steep, short hills though, so be prepared for a bit of a climb at times.
13. Dumfries to Thornhill on The KM Trail, Dumfries and Galloway
This scenic 22-mile trail might not be the most dramatic or well-known in Scotland, but it's important for another reason: It's named after Kirkpatrick Macmillian (1813-78), the Scottish blacksmith who invented the modern bicycle, and it passes through his home town of Keir Mill. It also takes in the stunning Drumlanrig Castle, the pretty River Cairn, and the Nith Valley.
14. Applecross and the Bealach na Bà Circular, Wester Ross
Last but not least, we have the fearsome, twisting, and beautiful 2053ft-high Bealach na Bà (Pass of the Cattle) in the remote Applecross Peninsula. Bealach has been voted one of the most incredible roads in the world by National Geographic, along with Route 66 in America, and what better way to experience it than on a bike? Especially as you get to freewheel all the way back down again.