You can cross the Lewiston Queenston bridge. If you search the documents on the Niagara Falls Bridge commision's website, they tell you that to bicycle across both the Lewiston-Queenston and the Rainbow Bridge you must cross with the car traffic. I have crossed the Lewiston-Queenston bridge several times last year on my Trike. I have crossed all 3 Bridges on my Trike and the easiest to cross is the Lewiston-Queenston Bridge. It can be tricky to cross the Lewiston Queenston bridge from the Canadian side as the bike entrance is located on the North side of the bridge from the Niagara Parkway.
Also there is a nice wide (Old Robert Moses Parkway Southbound Lanes) multi-use path along the river from the Rainbow bridge to the Niagara Power Project/NU/Devils Hole where you can take to get towards Upper Mountian Dr.
One way to get there is to make a left after customs at the bridge and head towards the Shelkof Geo musem. Enter the parking lot for the musem and look for a pedistrian bridge and head towards it and you will find the path. At the Northern edge of the path you will see another pedistrian bridge across the highway. Take this bridge and head for the parkinglot exit the parkinglot and turn left towards a light. This is Lewiston Rd. Take Lewiston Rd North and go past two overpasses and go Sacred Heart Villa. either turn right on the road just past the church or turn right at the Light (Military Rd).
If you turn right after the church, take the road to it ends and turn left. This new road will end at Military Rd. Turn right on Military Rd.
The first Light you come to will be Upper Mountian Rd. Turn left at the light and take it straight to Lockport.
Good luck and have fun
Jeff
Lewiston, NY