Bicycling in Scotland is variable. The best months for cycling are May, June, and September, when the roads are often quieter and the weather is usually better. Because Scotland's main roads are continually being upgraded, bicyclists can easily reach the network of quieter rural roads in southern and much of eastern Scotland, especially Grampian. In a few areas of the Highlands, notably in northwestern Scotland, the rugged terrain and limited population have resulted in the lack of side roads, making it difficult—sometimes impossible—to plan a minor-road route in these areas.
Several agencies now promote routes for recreational cyclists. These routes are signposted, and agencies have produced maps or leaflets showing where they run. Perhaps best known is the Glasgow–Loch Lomond–Killin Cycleway. VisitScotland has advice on a site dedicated to cycling.
You can take bicycles on car and passenger ferries in Scotland, and it's usually not necessary to book in advance. Arrive early so that your bike can be loaded through the car entrance.
ScotRail strongly advises that you make a train reservation for you and your bike at least one month in advance. On several trains reservations are compulsory.
ScotRail now runs a low-cost cycle-hire program via 12 major city and town stations. It costs £10 to register and the bike hire rate is just £3.80 per day.
The Cyclists' Touring Club publishes a members' magazine, route maps, and guides. Sustrans is a nonprofit organization dedicated to providing environmentally friendly routes for cyclists. Active Scotland, part of the national tourism agency, has a great list of bike routes ranked by area and difficulty.