The wheel speed is stabilised with 3 mechanisms to control
and reduce your feet sliding forward or backwards.
First, the wheels on both feet are connected by a mechanical
linkage that goes up each leg through a conduit. The linkage
makes them spin at the same speed. This helps prevent feet
sliding
apart in a forward backward direction.
Second, the mechanical linkage also connects to a geared
flywheel, to resist rapid changes in wheel speed. This helps
prevent both feet suddenly sliding out from under you
together, or one sliding out from under you while the other is
off the ground.
You can propel yourself forward in two ways: pushing
diagonally as with regular skates, or by using a normal
walking motion.
Skating sort of takes a bit more effort than normal as the
flywheel causes resistance to your increase in speed. On the
other hand it also resists decrease in speed.
With the parts so far, a walking motion would not move you
as far as walking normally, as the flywheel would allow your
foot to slip backward. To prevent this while walking from a
standstill, the third mechanism is a ratchet on the flywheel
preventing it from turning backwards.
You have to put up with the lesser walking progress when
walking from a roll. But you get it on top of the roll
movement.
There is a gear change mechanism (safely adjustable only
while stationary) to change how much the flywheel resists
wheel speed changes. Lower resistance makes skating easier,
and deliberate speed changes easier, higher resistance makes
you more stable and makes walking from a given roll speed
more effective.