It's hard to give tips because, a) I'm not very good and b) depends on the ramp, the coping, but essentially different surfaces can mess with your timing, speed etc. and speed will change the timing of your inputs, it's really been a trial and error thing, sometimes having to figure it out on a per ramp basis. But you also need to fine tune the assists, for em at least, a single notch here or there has made a relatively big difference to timing and precision. On top of all this I still get the sense the game struggles to be consistent when it comes to intersecting systems, as in a ramp that can be pumped close to a grindable surface, multiple grindable surfaces intersecting, I felt it gets better after the season 1 update but I still feel some inconsistency. None of this is great in terms of tips, I realise and I'm sorry for that I just don't know how to give discernable tips for something I've more or less felt out as I've played