Ok, You can also use Z botton, X is for relax/hold.
Basically the wheels are your whists and ankles.
When you contract is go backward, when extend go forwards.
You can turn relaxing one side (one front wheel and one rear wheel)
and acelerating the other 2 wheel. This is how I turn.
Also, disable the dq. /set dq 0
I usuallt race relaxed, you can do it relaxed or holdind all.
Hope it helps.