I've been looking at cycle clothing lately, and to
help reduce drag from the rider, without quite resorting to lycra, I've found that one can get windproof cycling jacket & hiking/climbing trousers which are very slim fitting, slippery-ish material & both breathable & water repellant too: combined with a thin but warm base layer such as merino wool top & leggings, this makes a very comfortable, lightweight, slimline, water
repellant & fairly 'slippery' setup, clothing wise at least - I'm afraid I can't help with the slim, athletic build aspect...
. There is some possible weight loss involved though
, depending what you normally wear when cycling - a lightweight wool top & windproof jacket (plenty warm enough even in the cold) can weigh as little as around 130-150g each, and trousers probably not much more, so thats a total clothing weight (excluding shoes, helmet etc.) of around say 7-800g or so, which feels very light indeed! - On the bike I keep feeling I must have left something behind, its so light!
I think even with a slippery & slimline rider 'outline' the correct rider position still makes most of the difference, and that doesn't look too comfortable to me, so I'll maybe settle for much slimmer & slipperier with a
slightly improved aero ride position (at least you
feel faster when you're more streamlined & in lightweight clothes
).
SPDs can also be used to increase speed, about 1 or 2mph or so, if you want to work more
.
Stuart.