NickOkay I put TPU tubes on my bike yesterday and it hasn't gone well so far, a pinch getting my tyres on during the operation, and a snakebite just now on a kerb I've taken many times using butyl inner tubes.....
On the plus side, there was a small but noticeable difference on gradients and slow grinding inclines, I've been using a gear higher for the same effort. Less rotating mass definitely helps.
Sze Hui