Following up on Frank's advice about shipping to the US.
Parcel Force Economy is surface mail. There is a reason they will not insure it. It takes a long time, often disappears or gets beaten up.
Parcel Force International Standard. (airmail) is the cheapest reasonable alternative, although the prices have been hiked quite a bit over the last two years.
Tandems need to be split in to two boxes as they are always over the weight limit for one.
Regards
Martin Coopland, Scotland, http://www.BatesBicycles.com