Cadence Revolution - available to subscribe in iTunes. This is a weekly podcast with free workout music. Each episode is about an hour long, with around 5-10 minutes of warm-up music, then around 40minutes of good, solid tempo stuff and then a warm-down. I've listened to a few of them, and the music is really good. The episodes I listened to were a mix of dance, electronic and soul (as well, one of the episodes has a bit too much salsa and reggae for me). Good, uptempo stuff. I'll probably take some of this out with me while mountain biking.
They don't describe each podcast individually, so you're never sure what you're going to get - since they have so many episodes, it would be much better to have descriptions so you could choose the ones with the music you like best. Oh - and there are also some advertisements and calls to visit the Cadence Revolution website halfway through or so. They're not too intrusive - unless they come during a killer song on some brutal climb, where you really need the music to help you get over it. In my case, it was on a casual road ride, so it didn't really matter.
There is no instruction in these, so you're free to design your own workouts, or pick one from the lists available in some of the sites in the Sufferfest Blogroll
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