Not sure if this the correct section for this. The transmission looks very innovative and ideal for a hub gear. The chain wheel can be changed with an adapter from the supplier http://pattersonbike.com/product/pulley-spider-adapter/.
It's a bargain price http://www.rosebikes.co.uk/product/detail/aid:442319 from this German supplier.
It's a bargain price http://www.rosebikes.co.uk/product/detail/aid:442319 from this German supplier.