Megatron Sheffield. Fat bikes.

ive always wondered if it was possible to ride a bike through the victorian flood defence system in sheffield, known as the Megatron. tunnels under the lower part of sheffiels city centre, carry the porter brook and the river sheaf, to their meeting point with the river Don.
All it took was a prolonged period of hardly any rain and very low river levels to make it worth a try!