I've been using a cycling specific jacket that has pit zips and a should flap. I always ride with my hydration under the jacket so that the shoulder vents work. The outer layer is a thin wind proof fabric of unknown material that is not very waterproof. The inside layer is a fish net fully extending to the cuffs. A polartec shirt usually keeps me comfortable down to 15*f when trail riding. I have a constant issue with the forearms becoming wet inside. On climbs the rest of my upper body may become moist but not soaked. Do I have to ditch the jacket or is there a work-around? I thought about getting a tailor to install zippers on the underside of the forearms.