Sad but inevitable to see the news on Contador's retirement. Will miss his big heart and fighting spirit and way of turning races upside down. What a career! I hope the up-and-coming attacking riders will continue to fight against the robot style of racing.
As per the conversation in some of the posts above - I saw this in today's Cycling Tips daily news digest - assuming the report is correct - which appears to cast further light on Trek being willing to let him race/retire on his terms in 2018, i.e. after the Giro if he wanted, and that it was Alberto's decision.
https://cyclingtips.com/news/report-trek-segafredo-aiming-replace-contador-aru/ (may have to scroll down a little to find the article)
Here's the relevant bit (the article also says they're now interested in Aru).
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"In the wake of Monday’s news that Alberto Contador will retire from professional cycling after this year’s Vuelta a España, Het Nieuwsblad is reporting that Italian champion Fabio Aru is now a major target for Trek-Segafredo.
"The Belgian newspaper states that the team had been keen to keep Contador and, if required, was willing to offer him a five-month contract for next season. This would have enabled him to race up to the Giro d’Italia and then stop. If accepted, this would have been similar to the agreement Tom Boonen had with QuickStep Floors this season, where he raced until the Classics and then retired.
"However Contador instead opted to end his career after the Vuelta a España. Lacking a clear team leader, the squad is now searching for another figurehead and feels that Aru may fit the bill. The fact that Segafredo, the team’s co-sponsor, is Italian is a factor, and so too Aru’s potential to win Grand Tours in the future."