Your first link refutes your thesis:
> Conclusion: The lack of internal consistency of the findings within the current study and of findings among prior studies, suggests that PA contributes little, if any, to the risk of TGCC.
Since you didn't link to the others, I can't respond to them, but I would note that the article I linked to noted that cyclists are more likely to be more health conscious, and thus would see a doctor more regularly and naturally be more likely to be diagnosed, among other potentially-confounding factors.
