A full back mesh jersey uses perforated or open fabric across the entire back panel, giving you maximum airflow where your body generates the most heat. It's the most breathable option available and feels incredible on scorching days or long climbs when you're working hard.
However, full back mesh comes with real trade-offs. That open fabric offers almost no wind protection, so it can feel surprisingly cold on fast descents or when temperatures dip even slightly. The mesh can also weaken your rear pockets — they may sag or stretch under the weight of a full water bottle and snacks.
Full back mesh is best if you ride in consistently hot climates or spend a lot of time climbing at low speeds. If your summer rides include variable conditions, early mornings, or fast descents, you'll likely be happier with underarm and side mesh panels instead.