1. HKT (Hook it) Podcast
Confusingly named (it sounds like Huck It Podcast) HKT podcast has gradually been growing, based in Sheffield in the UK but with a range of guests from around the world. Episodes tend to be between 1 and 2 hours, and whilst laid back in nature, tend not to be too waffly with some great insights into the industry and people that make it up.
2. Downtime podcast
Another high quality podcast, again out of the UK, the Downtime podcast leans towards the racing side of mountain biking. Guests are not just pro racers though, Chris interviews a lot of trainers and other team members.
3. Descent World podcast
Seems to of gone a bit quiet recently, but still a good back catalog of episodes.
4. Vital MTB podcast
Racing and industry based podcast, lots of episodes with some of them being very indepth.
5. Mountain Bike Radio
More of a collection of podcasts than a single one, Mountain Bike Radio is mainly US based, and a lot of it is quite regional, so not so interesting for people outside that area. However, the Apex Nutrition Podcast has plenty of great insights into diet for racing and training, as well as just general wellbeing, LW Coaching Show is also another source of great race training info and tips.