Watch Yer Weenie!
Gentlemen, your bike seat probably isn't doing your sex life any favors, writes Sandra Blakeslee in The New York Times:

In a bluntly worded editorial with the articles, Dr. Steven Schrader, a reproductive health expert who studies cycling at the National Institute for Occupational Safety and Health, said he believed that it was no longer a question of "whether or not bicycle riding on a saddle causes erectile dysfunction."

Instead, he said in an interview, "The question is, What are we going to do about it?"

The studies, by researchers at Boston University and in Italy, found that the more a person rides, the greater the risk of impotence or loss of libido. And researchers in Austria have found that many mountain bikers experience saddle-related trauma that leads to small calcified masses inside the scrotum.

This does not mean that people should stop cycling, Dr. Schrader said. And those who ride bikes rarely or for short periods need not worry.

But riders who spend many hours on a bike each week should be concerned, he said. And he suggested that the bicycle industry design safer saddles and stop trivializing the risks of the existing seats.

A spokesman for the industry said it was aware of the issue and added that "new designs are coming out."

"Most people are not riding long enough to damage themselves permanently," said the spokesman, Marc Sani, publisher of Bicycle Retailer and Industry News. "But a consumer's first line of defense, for their enthusiasm as well as sexual prowess, is to go to a bicycle retailer and get fitted properly on the bike."

Researchers have estimated that 5 percent of men who ride bikes intensively have developed severe to moderate erectile dysfunction as a result. But some experts believe that the numbers may be much higher because many men are too embarrassed to talk about it or fail to associate cycling with their problems in the bedroom.

And, sigh, bad news for lady cyclists, too:

In women, Dr. Goldstein said, the same arteries and nerves engorge the clitoris during sexual intercourse. Women cyclists have not been studied as much, he added, but they probably suffer the same injuries.

...Just as many smokers do not get lung cancer, many cyclists will never develop impotence from bicycle seats, the scientists said. What makes one person more vulnerable than another is not known. Body weight seems to matter: heavier riders exert more pressure on saddles. Variations in anatomy may also make a difference.

Dr. Goldstein said he often saw patients who were stunned to learn that riding a bicycle led to their impotence. One middle-aged man rode in a special cycling event to honor a friend and has been impotent since. A 28-year-old who came in for testing, Dr Goldstein said, showed the penile blood flow of a 60-year-old. A college student who had competed in rough cycling sports was unable to achieve an erection until microvascular surgery restored penile blood flow.

"We make kids wear helmets and knee pads," Dr. Goldstein said. "But no one thinks about protecting the crotch."