i've never ridden dunes, as most of my experience comes from riding around the hills, vales, and shores of the lower Connecticut River valley, but i have wondered aboot cruisin on sand mountains, and if that stuff gets into everything like a full day at the beach. my bud was an active competitor at the New Hampshire track, pretty good too and never got hurt (i'll leave bike jumping to the evil kanevel types- no thank you), until one day, riding his street bike, he got hit by a lady backing out of her driveway and right into him. weird.
fish around utube 'ADVChina' for the episodes from a few years back where 'sepentza' and 'laowhy86,' a couple of guys from south africa and New York, respectively, basically ride around china. they even opened up a bike shop there for a bit, before the dopey commies realized that they were filming the whole country, and came hard after them, with laowhy just sneeking past the border into hongkong with the bad guys right on his tail. of course, today he wouldn't have made it cuz there is no 'hong kong' anymore.
they also made feature length films of their adventures on bike.
all very informative, entertaining, and highly worthwhile, and no longer possible cuz red china is now closed tighter than ur gascap in a monsoon.
laowhy posted the definitive expose on the lab origin of the covid in spring 2020, a worldwide sensation that hit millions of views in a nanosecond ( i immediately reposted here), which only recently the world is now starting to understand. anyway, great bike travelogue.