There are 100's of awesome walking tracks. But thats the problem they are for walking only. I spend 2 weeks there every year at christmas and at least 2 weeks a year hiking with school there. Awesome place plenty of trails. Most trails out there are walking only and very tight single track. There are however some managment vehicle tracks that go from telegraph sandle (right near tidle river) to sealers cove but from sealers cove to oberon and back to tidal is all sand track which i imagine would be bad for your bike. Actualy the ride from telegraph sadle to the top of mount oberon is also a vehicle track so you could probably do that. The track out to lilypilly rainforrest boardwalk is also a large track and people would probably not have a problem with you riding it. the tidal river camp site is quite large so even if you dont ride and tracks it could be worth bringing a bike anyway, as it takes ages to get anywhere. If you are staying near 5th or 4th ramp bring a bike, but if you are on 1st 2nd 3rd or 4th avenue and are not going to ride trails dont bother. I hope this makes sense its very jumbled.
Haydn