While no Tour winner has been convicted, or even seriously accused of doping in order to win the Tour in the past decade, due to the previous era, questions frequently arise when a strong performance exceeds expectations. While four time champion Froome has been involved in a doping case, it is out of an abundance of caution that modern riders are kept under a microscope with bike inspections to check for "mechanical doping"[193]as well as Biological Passports as officials try not to have a repeat of EPO with 'H7379 Haemoglobin Human'.[194] Despite initially beginning as an operation to investigate the winter sport of Nordic Skiing Operation Aderlass is of particular interest to this sport because it involved people formerly and presently involved in cycling.