According to standard criteria used primarily for the assessment of clinical studies, the strength of this evidence was strong for fitness benefits, moderate for benefits in cardiovascular risk factors, and inconclusive for all-cause mortality, coronary heart disease morbidity and mortality, cancer risk, and overweight and obesity.

P. Oja, S. Titze, A. Bauman, B. de Geus, P. Krenn, B. Reger-Nash, T. Kohlberger (2011)

Regular cycling will help strengthen your cardiovascular system over time, enabling your heart and lungs to work more efficiently and getting more oxygen where it's needed quicker. This means you can do more exercise for less effort.