I like the Grumpys ride idea! from Dinkytown its probably 17-20 miles to Coon Rapids one way.. and there is an off rode bike path on Marshall/ East River Road
its pretty bumpy for road wheels but it gets you off the street for a few miles where the speed limit is 55 then back to the road from fridley on

Edit: oHh now that i think about it after grumpys in Coon Rapids we could end with a bon fire at the C.R. dam.. theres gotta be tons of wood down there