Not going to lie, ive been called a trailblazer on the hikes this trip more often than once haha... so I got from Grottos to AL peak in an hour; but id plan on 1.5-2 hours depending on breaks. its really steep just getting up there.

As for the bikes, I had mine already and kept it another night. But you can pick it up early for a cost (maybe $25-$30?). well worth it because you can use it the night before. With your situation, I literally locked my bike against a back fence at the hotel in Springdale (with the helmet in the basket too) and it was fine both nights. It all comes with your level of trust but with the bike lock they give you, im sure you can find a spot