Pacbitun is pretty far & all uphill from San Ignacio. Quite the haul by bike. Where are you staying? Crystal Paradise Resort also rents Mt Bikes from town (Savannah St) or their resort location - which is half the way to Pacbitun! Vans go pretty much everyday to Caracol. CPR offers this tour for a reasonable price as well. I second the recommendation for Patrick Warrior. You can often find him at the new little "mall" downtown SI, or call him at that number above.

www.barbsbelize.com