One leg working under the fixed bar path for pure stability.
Keep your front shin vertical and most of your weight on the front leg.
Staggering your stance under the fixed bar loads one quad through a deep knee bend while the glute drives you back to standing, and the track quietly solves the balance problem that makes free split squats wobble. With stability handled, all your effort goes into the front leg, straight down and straight up. It earns its place as single-leg strength work you can load properly, since balance never becomes the limiting factor.
Close family, but here the back foot stays on the floor. Elevating the rear foot on a bench shifts even more load to the front leg, so treat that as the progression once these feel strong.
Most of it. The back leg is a kickstand for balance, not an engine. If you feel the rear leg burning more than the front, shift your weight forward onto the front heel.
A vertical shin keeps the load driving through the front heel and shares the work between quad and glute. Because the bar path is fixed, set your stance length before unracking, not mid-set.
