Under Review with Update’s at any point in time

Grade 1 Gravel
Smooth, well maintained dirt roads that have either very small gravel chunks, or none at all, and are very much road bike-friendly

Grade 2 Gravel
Larger gravel clip, Expect potholes, washboard and probably loose, blown out corners. There is likely to be gravel outside of the main tire tracks that could cause an extra challenge if one was to come off their line. A road bike is just fine, but more skill is needed when cornering at speed

Grade 3 Gravel
Bigger gravel clip/rocks, Infrequently maintained roads that require a high level of skill when tackling on a road bike due to exposed rocks, tire eating rain ruts, sand bogs and any number of other unexpected challenges that could arise around the next corner. Unless a grade 3 Gravel section is added merely as a short connector

Grade 4 Gravel
Non-maintained Gravel/Dirt roads would be considered Grade 3 Mountain Biking due to deep ruts, rock gardens, and potential landslides left for the next gravel rider to stumble upon. Going with high volume tires will help provide pneumatic suspension, reduce the risk of a pinch flat, and provide greater traction is in the corners and on steep, loose climbs