Does cycling affect male fertility?
Cycling is a healthy, environmentally friendly, and efficient way of getting around but I’m yet to find a bike seat that gets anywhere close to being comfortable. There’s considerable pressure on your perineum (the area between your scrotum and your anus) when you straddle a bike seat, and this compresses the nerves and blood vessels that supply the penis1,2. This could theoretically result in impaired sexual and reproductive function.
Effects on genital blood supply, nerve function and temperature have all been hypothesised as potential problems but there is no good evidence that cycling for exercise and recreation causes problems with sexual function or infertility in men. Some early studies suggested that fertility and erectile function could be affected by cycling but recent larger and more rigorous studies do not show an effect3,4.
Being active and eating well are easy and effective things you can do to maximise your fertility. Cycling is good for your health and very unlikely to be harmful to your fertility. If you’re worried, maybe try a non-nose bike seat1.
 Munarriz et al., 2005. Only the Nose Knows: Penile Hemodynamic Study of the Perineum–Saddle Interface in Men with Erectile Dysfunction Utilizing Bicycle Saddles and Seats with and without Nose Extensions. The Journal of Sexual Medicine DOI: 10.1111/j.1743-6109.2005.00089.x
 Hollingworth et al., 2015. An observational study of erectile dysfunction, infertility, and prostate cancer in regular cyclists: Cycling for health UK study. International Journal of Surgery DOI: https://doi.org/10.1089/jomh.2014.0012