Sperm

May be genitic, but between my dad and myself (also generally do more miles than that and have had no problems with fucundanty) i have an 1/8th of the statistical evidanence they are using... 15 triatheletes... that's hardly a good survey number... sounds more like triathalons reduce sperm count to me?

How about Boardman's prolific breeding exploits, or Lance's getting another one, with only one ball? Plenty of other Pros, with the best part of 1000km/week during the race season, have had no trouble fathering sprogs. As you say, it's something to do with Triathlon, not cycling, but most likely that Triathletes don't have the balls to start with, otherwise they'd become proper cyclists :-)