Roadies pretty much agree with small variations, that race performance on the roadbike is something along the lines ot 2% bike/parts, 98% rider, or figures pretty close to that spec. So the guys who are beating you on the wknd on their $5000 bikes will likely beat you on a $500 roadbike with starter parts. Seems true in my experience, and seeing the range of cyclists who pass me.
I was wondering if this was true for MTB as well, or if the bike matters more? I'm guessing it would, especially for downhill dominant races, but I wanted to hear from those who have more experience than my noobness. (Ulterior motive: intending to upgrade my steel 35lb Gary Fisher, but hesitating to pull the trigger if it won't improve my riding much.)