I had my 2-piece converted into a 1-piece for the racing by 9-lives in Guildford.
I never used to feel comfy moving round the bike too much, not so much the Mike Hailwood school of loosely sitting still on a bike more like a feeling of being cut in half at the top of my thighs
, it hasn't helped me get my knee down, that's more to do with my back being too rigid (well it does have a certain level of built in carbon & titanium reinforcement!), but I'm fast running out of toe-sliders
