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Key events can be any memorable event, for example an impressive victory but also a major crash, bold solo or anything that makes for sporting memories.
Over 3 minutes behind Simon Yates in GC in stage 19 of the 2018 Giro d'Italia, Chris Froome attacked on the Colle delle Finestre with 80k to go. He went on the win stage and took the Maglia Rosa. Yates lost over 38 minutes.