The Fundamental 26” wheel line level uses Rotary hubs, plain gauge spokes (2.0mm) and Fundamental rims. The rear wheel is available with single speed hub with 10t driver or cassette hub with 135x10 female axle with side bolts. Front hub is compatible with 20mm forks only. conversion kit 20mm to 15mm (110x20 to 100x15) available separately.