BikerBoy from Edwardsville, IL on 8/25/2014 12:34:12 PM:
I have ridden the Riverfront trail quite a few times, crossing between IL & MO. You can now make a loop by crossing the McKinley Bridge (with its spectacular view of downtown)and continuing on the Confluence Trail on the IL side, and then crossing the Chain of Rocks bridge back to MO.
So you really have 2 routes from downtown up to Alton. I have never had a problem with safety on the Riverfront trail. You should know that some parts are very industrial, but that's a nice change. The trail goes up a steep hill on Riverview Drive as it approaches the Chain of Rocks Bridge, then comes immediately back down -- so a lot of riders just stay on Riverview for the 1/2 mile, but it is a very busy street.
Cross the Chain of Rocks bridge, and catch the Confluence Trail all the way up to Alton. Jump on the Clark Bridge and pick up 67 on the Missouri side. That is a busy highway, so be careful. Take 94 out to Machens, again, being careful. I have done this route a couple of times with no problems.
However, I would never park my car at the Chain of Rocks bridge, especially on the MO side.