i this route a couple of times per month.
I go up 43 until River Rd (its a right through the barrier just past the park)
Then down along River Rd.
Until it takes a sharp left at that point take a right onto the bike path into Lake Oswego. Go over the bridge and up the hill, take a right on the first road and continue until the end where you go left (about 4 blks) and go 2/3 blks to 43/State ST. Here I go right and take State (I guess you could ride on the side walk) up to Terwilliger and then left onto the bike path trough Tryon Park.
After wandering through the park you end up back at Terwilliger which you can then just follow all the way to downtown
have a good ride