Middle aged men who spend nine hours a week on their bike are more likely to be diagnosed with prostate cancer, new research suggests.
A British study of 5,200 cyclists is the biggest research project ever conducted on the health impact of cycling.
It suggests that cyclists in in their 50s who bicycle for more than nine hours a week may be up to five times as likely to receive a diagnosis of prostate cancer.
The team of scientists at University College London, found there was no link between cycling and infertility or erectile problems - an age-old health myth.
But the statistical link with prostate cancer could create a new, and unexpected, health concern for the millions of men who regularly cycle.