Generally, no, you cannot wear a fanny pack (belt bag) while riding TRON Lightcycle / Run at Magic Kingdom. Because of the unique "bicycle-style" restraint system where you lean forward and a back bar secures you, any bag worn around your waist or across your chest would interfere with the safety mechanism or be highly uncomfortable. Disney provides free, double-sided lockers located just before the boarding area to store your fanny packs, backpacks, and large cameras; these are easily opened with your MagicBand or park ticket. However, the ride vehicles do feature a small, built-in storage compartment directly in front of the handlebars. This compartment is specifically designed for very small items like a smartphone, a slim wallet, or a pair of glasses. If your fanny pack is extremely flat and small, you might fit it in there, but most guests find it much easier to use the designated lockers.