I'm new to touring, and doing much research on it.....

The ACA bike routes are interesting and a little confusing to me.....particularly the Sierra Cascade route from Ashland, OR (where I plan to begin a trip) that meets up with the Western Express. I'm confused because it seems like the route is on I-5. Is that right? I couldn't imagine riding on the interstate and I was wondering if anyone had experience with this route could explain it to me. Thanks

I'm not familiar with that particular route, but it wouldn't be uncommon to do some sections on interstate shoulders where there aren't any good alternates. I know that in California it's legal to ride your bike on freeway shoulders anywhere that there isn't a specific sign prohibiting it. Of course many freeway ramps do have such signs, but, e.g., I-5 is bike legal all the way from the SF Bay Area until you get to Santa Clarita outside LA and there are shorter stretches that are also bike-legal elsewhere such as the part through Camp Pendleton north of Oceanside. Riding the freeway shoulder is pretty safe based on the statistics I've seen, but it can be noisy and there's frequently lots of tire debris that can cause flats due to the small wires left behind as the tire pieces deteriorate. So I wouldn't expect the ACA route to remain on the freeway where there are better options available.

We rode from San Diego to Reno using the SC except at the ends of our route and were not on I5, but yes it does use I5 for a bit near the CA OR border.

I have ridden in the interstate before and found the experience varied from just OK to very nice in the cases I have done it. On the Trans America we were on I80 for a short ways and it was safe enough, but not all that aesthetically pleasing. On my 2009 Santa Fe Trail tour I rode from Springer NM to Santa Fe and much of the day was on I25. I25 in NM was actually very nice. Clean wide shoulders, good scenery, traffic not all that noisy most of the time.

I do not know how I5 is, but I wouldn't let the fact that it is an Interstate worry me much.

Agree about interstates out west not being that bad in most cases. I have ridden them in WY, OR, ND and MT. As noted, they are often not that scenic, can be noisy and there can be debris on the shoulders, but they are nothing to really worry about.

I rode the Lewis and Clark from Portland to Missoula this summer. There were several places in the Columbia Gorge where the route went onto the freeway - I-84. It wasn't bad, but not good either. The good was that the freeway route smoothes out all the hills. When I got off and took smaller roads I went up and down, up and down. The freeway was close to flat, and the few hills were long and gradual. There was a wide shoulder most of the way, but there were also lots of places where guard rails and other obstructions constricted the shoulder to worrisomely narrow. (Is worrisomely a word?) I missed an exit and ended up in a long tunnel with no shoulder and drain grates that would grab a front wheel. It was bad! The other thing was how noisy it was. I met another tourer who was wishing she had earplugs for the freeway sections.