I'd also like to add that MTB is so diverse. @
Hr1 I think you are speaking out on full on downhill (DH) racing, which is pure nerves and skill. On the opposite end of the spectrum you have cross country racing (XC), which has lots of crossover with road and cyclocross and some of the worlds fittest athletes.
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"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste