tl;dr Given that every previous attempt at veloduct-style seg infra in London has resulted in stuff that's a bit shoot, and that faster cyclists who want to get from A to B can already do it quite nicely using a combination of bus lanes, filtered permeability and just plain ordinary cycling-on-the-road, you're not really providing any compelling reason for any of them to support you in your quest to build more seg infra if you can't adequately explain why it won't be more a bit shoot all over again. Encouraging non-cyclists to take it up is great, don't get me wrong, but don't expect support from people already cycling if the most likely net effect is to make it worse for them.