Coming in from a runners background I see cycling basically the same as running. You need one long ride a week that goes I would say 60-80 miles. Then one medium day of going say 40 miles. Then two days of one being working on intervals, hills, or whatever ever, and finally a day to just spin easy. Personally I was riding full time and not running I would want to ride 200 miles weeks for sure but at times 250 would be ok. At 205 pounds you probably are a bit big to be great in the mountains but could be fun to work on that.