arenacross is tricky, because it requires a lot of confidence, and the skill, to back it up. there is very little margin for error. the catapult jumps are not hard at all, if you know how to set up for them. if you have access to a private track, or smaller public track, i would suggest asking the owner, (or track designer) to build you a table top, with a near vertical launch, and a short runway. also request a really short, gradual berm or two. this will give you most of what you need to practice for arenacross. it works best, if you have a tall berm before the table top, so that it is not so hard for you at first, then you can just start squaring off at the bottom of it, once you are confident. for the whoops, i would suggest starting off, by wheeling through each gap (individually/ at walking or jogging speed) just give bursts of power, to keep the front end skimming from crest to crest. you will kind of get the feel for it, and get a rhythem going... then you can start adding speed. the rhythem jumps just take practice. on my supercross track, i built a rhythem section with a table-roller-roller-step up sequence. there are like 6 different ways to ride this section, but they all require spot on accuracy. (i am currently just coming off of a broken tibia/surgery, and torn ankle ligaments as a result of getting off rhythem in this section). when used, and not abused, a section like this can be the hot ticket in practicing arenacross style riding. it will also help you if you make your "practice catapult" bigger than the ones at the races, then you have an even bigger advantage, and you can start trying to jump them lower using that extra momentum.