I´m not that familiar with biking around Amsterdam, but I know that Waterland, the area just north-east of Amsterdam is to my opinion nice for biking around. Places like Durgerdam, Ransdorp, Holysloot, Broek in Waterland and further Monnickendam, Edam and Marken are really lovely, skip to my opinion tourist trap Volendam. The route Amsterdam Central Station to Monnickendam is about 25km, needing some 1½hour.
I think you can rent bikes in several places outside Amsterdam and go to there with the bus. TI´s (VVV´s) can provide more info about the most scenic / interesting routes. If there is wind to deal with or you want to cover larger distances you can think about an e-bike.