This video highlites the body positions a rider must assume to navigate twisty, curvy roads. Also shown is a PIP view of a forward facing camera so you can see the road ahead. To ride a curve you are sliding your rear end off the seat to the inside of the curve. This puts your body weight over the centerline of the bike, helps in leaning and also helps when accelerating out of the turn. Your weight is holding the bike over so you can apply much more engine power exiting the curve to stand the bike up with your body weight holding it down. Enjoy the following video of my son's tuchus (Yiddish: butt, rear end).
Riding a curvy road is not a relaxed sit on a seat. It is a good idea to keep your seats oiled, on the bike and your leathers because you are sliding left and right so much. You could do a planted butt ride but your speed would be much, much slower. The bike has to lean to take curves at speed. You also have to 'counter-steer' the bike to make it lean into a curve. To take a left curve, turn the handlebars to the right will make the bike lean over to the left. Counter-steering is what turns a motorcycle. Accelerating out of the curve will stand the bike back upright. I hope you enjoyed my son's sliding butt ride.