Vision Fitness E4000 dual-action upright exercise bike The E4000 dual-action bike gives you the best of both worlds with an upper and lower body workout. For many years, air resistance has been the standard for dual-action bikes; however, with the magnetic technology offered on the E4000, you'll find that the E4000 is the quietest dual-action bike on the market. It is also the only dual-action bike that allows you to control your resistance, which is important if you want to make progress in achieving your exercise goals. Like new.