The aim was to compare the training characteristics of junior, under 23 and professional road cyclists. Training data collected during the 2019 competitive season of thirty male cyclists, divided into three age-related categories (JUN; U23; PRO), were retrospectively analyzed for training characteristics, external and internal training load. Higher duration per training session were observed in PRO (2.6±0.3 h) compared to both U23 (2.2±0.3 h; P<0.001) and JUN (2.0±0.2 h; P<0.001). Elevation gain per distance was higher in PRO (13.8±1.9 m·km−1) compared to U23 (10.6±0.9 m·km−1; P=0.001) and JUN (6.7±0.3 m·km-1; P<0.001), and in U23 compared to JUN (P<0.001). Annual total work was lower in JUN (3694±467 kJ·kg−1) compared to U23 (5268±746 kJ·kg−1; P=0.001) and PRO (5759±1103 kJ·kg−1; P<0.001). eTRIMP per hour was higher in JUN (151±40) compared to both U23 (115±23; P=0.003) and PRO (112±22; P=0.013). JUN spent more training time at medium and high heart rate intensity zones compared to U23 and PRO (P<0.05).