Old Ned":18m18rt3 said:
It's actually less rigid. A single fat (but thin-walled) tube is a better use of material. That is why bikes have big fat tubes and not pylon-like wire spaceframes. However, the mixte 'twin lat' tubes look graceful. The main force on a bike (beyond rider weight) is the twisting between steerer tube and seat tube caused by pedalling. Tony Oliver's book covers it in great detail.
