Hey V!! I'm so excited for you.
You'll do great. Have you got a race plan? By that I mean strategies to deal with things as they come up. It's a good thing to think about. Like what will you do if the run is really painful and just sucks, how are you going to motivate yourself to keep going. Or what will you do if your stomach goes south. Having pre-planned ways to deal with these things is helpful. I'm sure you have lots of experience with this with cycling.
BTW - I just finished crewing for Race Across Oregon. It was an amazing experience. You might seriously want to think about it. Maybe not as a solo but as a two person team or something. It was very cool.
Living life like there's no tomorrow.
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2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS