North Shore gravel rides are typically multi-surface: a mix of paved, dirt, and gravel riding. Ride ratings may include more than one category.

Types of Gravel Rides

Category 1

Smooth well maintained rail trails or dirt roads that have either tiny gravel chunks or are hardpacked surfaces. These are road bike-friendly and offer little more difficulty than riding on pavement. Slightly lowered tire pressure will allow a better grip. 
Ideal bike: Road or gravel bike   
Tire size: 28-32mm   
NSC rides with this type of gravel: NH Northern Rail Trail, ME Eastern Trail

Category 2

Dirt/gravel roads and wide single-track or dual-track trails with potholes, washboard, and occasional loose surfaces (dirt, roots, leaves). Rougher trails are primarily used as connector segments. Longer sections (over 1/3 mi) are smooth enough that side knob tires are not required for traction. A road bike is still fine if it can fit the recommended tire width, but more care is needed at speed. A larger tire size and lower pressure is recommended to reduce the risk of pinch flats and increase the pneumatic suspension a higher volume tire allows.  
Ideal bike: Endurance road, all-road, or gravel bike   
Tire size:  32-35mm   
NSC rides with this type of gravel: Amy & Mickey’s Gravel Adventure, All Mixed Up 
Event ride: Raid Rockingham    

Category 3

Infrequently maintained trails and roads that require a higher level of skill due to longer sections with exposed roots or small rocks, runoff ruts, sand, or steep loose climbs. Unless a Category 3 Gravel section is added merely as a short connector, a gravel bike with 33-40mm tires that offer small side knobs is recommended. Lower your tire pressure to 30-40 psi depending on your weight and the minimum sidewall rating. 
Ideal bike: Gravel bike    
Tire size: 33-40mm  
NSC rides with this type of gravel: Mickey’s Gravel Ride (Level 2/3),    
Event rides: Kersage KlassicD2R2 100k, Noah Leavitt’s Z2Z and Cider Donut rides

Category 4

Class IV forestry roads, 4x4 jeep tracks, or hiking trails with deep ruts, rock gardens, and other loose surfaces. High volume tires or a suspension system will help cushion the hits and reduce the risk of a pinch flat, and provide greater traction on corners and steep, loose climbs.  
Ideal bike: Gravel, Adventure, or modern hardtail MTB   
Tire size:  42+mm, or Road Plus (650b wheels with 50+mm tires)   
NSC rides with this type of gravel: n/a   
Event rides: D2R2 100 mile+, Unbound Gravel