In LBZ act 2, there are convex 90 degree curves that Sonic can run on -- and when he does, it seems impossible for him to run "too fast" so that he slips off, he always runs around the perimeter even with maximum possible ground speed. In my own tests re-implementing this same curve, I was unable to prevent him from running so fast that he "flies off" the top and becomes airborne instead of sticking to the surface (specifically with the movement "pop" described in the physics guide where his feet sensors rotate from right-wall mode to ground mode combined with high velocity). Given that when his sensors rotate from wall-mode to ground-mode, his rightmost floor sensor moves 10 pixels (radius of 19 -> radius of 9), and at ground speed of 16 on a 45 degree angle his x position ought to move ~7-8 pixels, then in total the "pop" should be able to move his floor sensor 17-18 pixels, possibly bypassing an entire tile's worth of collision. This is exactly what I am experiencing in my own recreation of the game and the cause of his "flying off the edge" behavior. Despite this analysis, that is not what actually happens in the game, so I analyzed what does, frame-by-frame, after hitting a red spring and was surprised to see this: The position and angle of his sprite show that he has a significant downwards angle, but the position of the very bottom of his feet show that the sensors must be colliding with a 45 degree or even shallower tile. What is the game doing here -- how can Sonic be moving at a near straight-downwards angle while also colliding with a tile that has a visibly much shallower angle? Is there some magic here that is the secret behind him not flying off of these ledges?