|Downhill Street Bicycle Competitive Event is a new sport.|
But without funding and without any course construction planned, then the most likely practice is for bicycle clubs to get permits to run single-element events on city streets.
But a constructed course with about ten curves per mile, with each curve having an effective radius of about 100', that course layout limits ultimate downhill speed such that bicycle control in the curves, at significant g-forces, is most important.
A mountain road would not have the same characteristics of a constructed course. A mountain road, as a non-standard course, would require a limit on gearing. Or if the mountain road was extremely wide then it might be possible to layout a tighter course within the road width. I suppose layout with paper cones and glue.
Well a standard curve with an effective radius of about 100' is explained as two 25' wide streets that intersect at ninety-degrees. Then if the inside point is rounded with a 12.5' radius, the centerline rounded with a 25' radius, and the outside point rounded with a 37.5' radius, the radius of the bicycle path within the pavement width could be as much as 97.86'.
Now the website can list clubs that subscribe to the rule book and list their upcoming events.