Channel 4 says: "Male fertility is on the agenda as a group of mountain bikers learn how their hobby could be doing them more harm than good. Sperm samples are supplied to Dr Jessen, with one shocking result."
'Cycling causes impotence' raises its ugly head on a frequent basis. Click here for a long article discussing the history of ED and cycling, and why cycling is often unfairly tarred with this particular brush.
The long article contains a video of the Singletrack publisher getting his wedding tackle wired for science, but don't let that put you off.