It's 10 miles from the ramp in Noblesville to 116th St. If you want to take out sooner, skip the river road park access and take out at 146th St. The river road park access is too much walking to get to your vehicle/gear especially if you are like me with a 7yr old and camping gear, canoe, big cat rods, cooler, and other odd fishing stuff.
You can park directly under either bridge and generally don't see hardly anyone on the river. Really good small mouth and catfish fishing.