There will be lots available. You do not specify times or types, you just head to bike area when you are ready to do your ride, sign your waiver, and grab whatever you want.
And don't worry about the "1 hour" rental - that's island time...which means you use the bike until you have to get back on the ship
Last suggestion: if you are cruising in the summer, be prepared to bike only first thing in the morning or you may melt...it get's pretty warm in July on CC...
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