Water Front Bikes in downtown Portland has the largest collection, including tandems if you want to ride with a partner.

BBC: Portland's urban adventures

Another is that boards sometimes turn to tandems when firms are in trouble.

ECONOMIST: Schumpeter

An inclined lift can carry up to 27 people as well as accommodate bicycles, tandems wheelchairs, pushchairs and smaller motorised disabled scooters.

BBC: Tyne pedestrian tunnel to shut for ?4.9m one year revamp

The new so-called inclined lift can carry up to 27 people as well as accommodate bicycles, tandems wheelchairs, pushchairs and smaller motorised disabled scooters.

BBC: Tyne pedestrian tunnel to shut for one year revamp