A. Easy - Suitable for anyone who can ride a bike and can manage a bit of exercise. No routes are 100% flat, so expect some climbs and descents.
B. Moderate - Ideal for occasional cyclists and above, or a relaxing trip for better riders. Reasonable fitness required such as cycling, hard walking or similar once or twice a week.
C. Strenuous - Suitable for fit & confident riders. Fitness is more important than ethnical ability for trips of this level, and some specific training or preparation is recommended, e.g. running, cycling, swimming or aerobics two to three times a week (preferably cycling!).
D. Extremes - Long cycling days and tougher terrain (for both on- and off-road trips) requiring specific experience of more demanding and technical cycling. You should be very confident of your physical condition and bike handling skills.