There’s no mention of bicycle parking on the Miami GP website. Doesn’t mean it’s not available near the gates. Alternatively, you could ask one of the local homeowners who sets up temp parking to look after your bike for you for a small fee.

I have answered your question in the Miami Facebook group, but I’ll answer again here. The fan areas in Miami are separated into different zones, most of which have their own fan zone. But most of the zones, and as a result, most of the fan zones, are open to all ticket holders to explore. Same goes for the general admission areas around the circuit. You can watch from these areas, even if you have your own grandstand seat.