Pitcairn Island ? Wikipedia says there is a population of 50. Is there even roads to ride on? Hopefully you have some form of Postal service/shipping. I suspect it isn't often or cheap. You obviously have www access. So you could list on Craig's list from your old town, or Craig's list in any town. Just provide details in listing bike will be shipped from a dot in Pacific ocean. People can and do search all of Craig's list for an item. I've listed items in little old Reading, PA, Craig's list, and sold items out of state, buyer asked if I would ship, and of course offered to pay. And of course no fees with Craig's list. Item was listed for a month. And of course you can sign up with ebay, unless you gave up all credit cards. Biggest problem won't be the listing, but finding a box and packing the bike to make a long trip. Not that it applies, but I did sell on ebay a bike, packed and shipped to Hawaii. At that time FedEx was best deal.
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BierHaus Bertolette Road Bike, built 2007
BierHaus SRT Trail Bike, built 2010
Fuji Mt. Pro - 2007