When you drive up Extrom from Promontory you will realize why mountain bikers and cyclists have given this road descent such a dramatic epithet. You will be able to park at a convenient pull in but beware of traffic of all types coming downhill. Take care with the loose stones and Devils Club as you step up to the cache.
Having descended this road in the wet on a mountain bike, I can see how it got its nickname on websites that record cyclists activiites such as Strava. The sweeping, steep bends encourage speed but the loose gravel is a big hazard. You may be lucky enough to see a cyclist negotiate this hil,l but if you do please don't distract them - they need all their concentration for the road!