The connection is read-only. Gemini can look at your data to answer questions, but it cannot add, edit or delete activities. That is the part most people worry about, and it is the right default.
It does see a lot, though. The consent screen says Gemini will read your workout activities, performance metrics, training plans, gear, clubs and profile details. It also says parts of your conversation, along with your name and email address, may be shared with Strava and handled under Strava’s privacy policy. If you would rather your race chats stay out of Strava’s hands, think about that before you tap authorize.
A sensible habit: connect, ask what you need for a training block, and review the link every few months. If you stop using it, remove it, the same way you would clear out old app permissions on your phone.
How to disconnect Strava from Gemini
You can switch it off at any time. In Gemini, open Connected Apps and remove Strava. You can also withdraw access from Strava’s own settings.