Do you have to bring a bike or can you lease one? Do they supply it to you how does that work?

You have to bring your own bike and it is free , open to public

It is all open and free to the public but you need to bring your own bike.

Also bring a really good helmet!

Advised to bring: helmet, bike, water, tools, air pump, first aid kit, sun block, snacks, camera and sun glasses. This is an unmanned park, no ranger, no assistance, ride at your own risk.

it is just a public park (no rentals)

Can you just walk the trails?

You have to bring your own supplies. Very cool park

Yup, bring your own (competent) bike, or rent one from a shop in Mesa.