Cedar River Trail
There is a trail that starts at Lake Washington in Renton which follows the Cedar River all the way to Landsburg. Most of the way this trail runs next to the Maple Valley Highway, but because it is so close to the the river you almost don’t notice the cars. Although the King Couny website shows the pavement ending in seven miles, it actually continues a long way beyond that (as illustrated in the email you’ll see if you click the 2005 page.)
Here’s a link to the King County page on this trail.
One really interesting possibility is the rumor I’ve heard that the City of Seattle is willing to allow the trail to be extended through the watershed along the Cedar River all the way to Rattlesnake Lake. That would allow a connection to the Snoqualmie Valley Trail and the John Wayne Trail .
Currently at the north end of this trail you can connect with the Lake Washington Loop and with this connector you can hook up with the Interurban – Duwamish trail system. (Eventually there will be a dedicated trail linking the Cedar River Trail with the Lake Washington Loop in Gene Coulon Park. ) There is supposed to be a trail linking the Cedar river trail with the Eastern part of the Green River Trail (via Lake Wilderness) which would allow for a very interesting loop ride.