The latest hi-tech mesh fabrics are extremely light and sweat evaporates from them almost instantly, there is little need to unzip them. So we just ditched the zipper altogether.
A classic wool jersey is about 290 grams, an early ‘90s synthetic jersey is 170 grams. Our new zipperless mesh jersey weighs about 75 grams almost 100 grams less than a conventional polyester jersey. That’s the difference in weight between a 105 and a dura ace Shimano cassette (which costs over 200 dollars more).
The other big advantage of the zipperless jersey is that all the bunching fabric and stomach bulges are eliminated. The result is a very clean, streamlined fit - even in a cycling position. So it's less rumpled and more aero.