Can't Roll Back-in
Mechanism / Why It Happens
The key to a smooth roll back-in lies in how a ramp Smith grind differs from a ledge Smith grind.
On a ledge Smith grind, once you're locked in, you can keep your weight over the back truck and simply ride off the end of the ledge. But if you do the same thing on a ramp, you're practically setting yourself up to catch the rear truck on the coping and fall. Rolling back in can definitely feel scary, but in fact, the farther you lean back, the more dangerous it becomes.

What to Do
How smoothly you roll back in depends on how well you can shift your weight onto your front foot.
During a Smith grind on a ramp, you do keep your weight over your back foot because there is a lot o