When I read your post I thought you were talking about Trans Baviaans 
I have done the route a number of times (both ways but on a motorbike… 
) and it is not all that technical. Some guys do it on gravel bikes. There are some serious climbs though!!
Here is Timothy Hammond’s stats from Strava… Ave of 29.2km/h… CRAZY!!!
Search for him on Strava, then you can download the GPX Track as well. (The race was 11 Aug 2018)