The formula used for grading is based on the distance of the route and the height of climb. This then produces a number which can be compared against a numerical table to provide a difficulty score. The scores quoted on this website follow the following approach and narrative:
Score 0-99 = Grade 1 – Moderate
Grade 1 routes are great if you are new to cycling as these routes are usually shorter and flatter.
Score 100-199 = Grade 2 – Challenging
If you are new to cycling but want a challenge, Grade 2 routes will offer a rolling route with some challenging aspects.
Score 200-299 = Grade 3 – Difficult
If you are a regular cyclist and looking for a challenging event that won’t break the legs a Grade 3 is the event for you. Usually around 3000-4000 ft of climbing over a middle distance route.
Score 300-449 = Grade 4 – Hard
Grade 4 events are for regular, experienced cyclists. Typically routes of a longer distance with challenging climbs included. Training for Grade 4 events is recommended.
Score 450+ = Grade 5 – Very Hard
Grade 5 routes are not for the faint hearted. They will include very hard climbs, usually over a longer distance. It is recommended to train for events such as these to ensure you are fully prepared. Only a handful of events will have a Grade 5.
(Grading information provided courtesy of British Cycling)