Way back in the 1960's this course was used for car racing, it's about 1km long and the record is in the vicinity of 1 minute.

It's ... steep ...

You'll be needing a granny gear on a mountain bike and excellent balance skills to get up it, dry weather only ...

You'll get most of the way up it wondering what the fuss is about, then you go around the right hand hairpin, the road starts to turn left, and it will all make sense.  The steep section is about 80 metres long.