How is it possible to get 100% in the game (complete all shreds and medal events)?

Because say I'm amateur I just do the medal events and pretty soon I get enough hype to move up to rookie (or whatever comes next) and then all the amateur shreds that I didn't play disappear and are not accessible from the main map or the past events map. So how does one access these shreds again?

These ones pop up again through out the game, dont worrey you should be able to do them all.

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Lol, I guess what really threw me was the first time I got up to Pro Master level having completed only 9 medal events (I got most of my hype from shreds). So I found myself Pro Master and stuck with no cash, minimal sponsorship and no means of getting more cash (lower level events weren't popping up). So now Im making sure all the events pop up by concentraing on medal events only (apart from the trick off with Zoe cos I love her bat wings and want them) and deliberating losing early events so as to keep my hype to the minimum and then going back and replaying them when Im Pro/Semi-pro and breaking all the records to get high level sponsoship for the pro events. Seems kindof counterintuitive and I really hate fannying about waiting for the other riders at rookie level to pass me but I guess I get to explore the course.