Team Sky principal Dave Brailsford has defended the team's zero-tolerance policy on employing people who have doped in the past.
The revelations from the US Anti-Doping Agency investigation that led to Lance Armstrong being stripped of his seven Tour de France titles has had a knock-on effect for Team Sky.
Michael Barry, who rode for the team since its first year in 2010, retired before admitting to his use of performance-enhancing drugs while riding with Armstrong at US Postal earlier in his career, while Bobby Julich and Steven de Jongh - both members of the coaching staff - departed after admitting to doping during their riding careers.
Brailsford told Sky Sports News: "I don't think we can deny it was a challenging period.
"Both at Team Sky and British Cycling we try and run systems of continuous improvement and, within that system, as soon as any new information hits it then we look at it and audit it both for negative and positive information. (Then we ask) 'Do we need to change and update our system?'
"What happened with the Armstrong scenario is that all this information hit the sport. We looked at how this information impacted on us as a team and we then amended and updated our system.
"It is a challenge when people leave the team but we have a very clear (zero-tolerance) policy - it's a policy we believe in, a policy we started the team with and it's a policy we intend to continue with. I think that will be the cornerstone of our success."
Sean Yates, who mentored Armstrong when the American was a young professional, also retired from his role as senior sports director at Team Sky.
Yates has always denied doping during his career and of having any knowledge of Armstrong's doping - and Brailsford hopes he is not tarred by association.
"In Sean's case he did a fantastic job for Team Sky and was a key member of the Tour de France winning team," said Brailsford.
"Sean has had ill-health and he was coming to the point where he was considering not living his life on the road anyway. He made the decision to go back to his family and stop living out of a suitcase all of the time, he has spent an awful long time away. We respected that decision.
"I hope he doesn't get grouped into that overall thought process (surrounding the Armstrong revelations)."
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