I have a Montane Velo pertex cycling jacket and it works well at keeping the wind out without making me boil, but it obvious it's been made by a mountain clothing company and not a cycle clothing one.
The arms are the correct length for the bike, as is the length ofthe tail, but the belly area is rather baggy and the arms are way too baggy. The whole thing inflates in the wind quite alarmingly. I tried wearing a 200weight fleece jacket underneath - and lo and behold! it's a perfect fit - absolutely ideal for cycling in sub-zero temperatures! For it's intended use it's been cut incorrectly. I'm no racing snake either BTW, I bought a medium(40"!) size as the small was just a bit too small for my 42" chest.
In it's defence, is does keep the wind out, keeps light rain out for about half an hour and does pack down to the size of a tennis ball. In it's mesh bag it lives on the bike, forgotten, until it's cold or raining when it makes a triumphant appearance. Just ask Lardyboy!
My search for the perfect lightweight windproof continues....