I've ony done from the Rattlesnake trailhead to the tunnel and through it. I did it on an old mtn bike with an elastomer suspension fork it was pretty rough overall - next time I'll take my new mtn bike with better fork. I'm sure you could do it fine on a wide-tired touring bike, but you'd get pretty beat up - it's not a smooth path.

I have heard it's basically Okay through Ellensberg, but beyond gets very spotty with a lot of detours around private land and the like.

- Mark