Epic bike rides/touring

Hi-
I’m interested in various opinions on the value of epic bike rides or touring as part of base building for triathlon training. I’m talking about taking a week and riding 500-900 miles down the west coast or something roughly equivalent – very easy pace no doubt.

I’ve been riding for several years, but never really focused on it. I’m in pretty good shape from my running (handful of marathons) and I think I could manage the ride. My only question is, how does this apply to training.

Say, I want to do an ironman next year (done a couple of halves already). Would this be useful as some sort of base-building this year?

Thanks!

I know a bunch of guys who ride SF to SD every January in 5 days. They swear by it. Or, check out http://www.slowtwitch.com/mainheadings/features/skidmarks/epiccamp.html and http://www.xtri.com/article.asp?id=858. Or, go to Gordo’s site and do a search on epic camps, including do it yourself.

Last year 3 weeks prior to London, my season’s “A” race, my brother and I rode John o’ Groats to Land’s End (North Eastern tip of Scotland to South Western tip of England), 948 miles in 8 days for a kids’ charity, typically knocking off our 120-mile days averaging 16mph (first couple, of course, were a bit over-enthusiastic). We carried “light” luggage (both on regular C’dales) in a large Carradice saddlebag.

We got nothing but stronger over the week (butt problems aside…), and it delivered the biggest step-change in my cycling performance ever.

Zero science behind my experience, but highly recommended and a big adventure.