Is Roller Skating Easy If You Know How To Ice Skate?

In general, yes, it's definitely easier to learn to roller skate if you can ice skate, BUT in artistic roller skating (figure skating, using quad skates) it's harder work to achieve the same moves than ice skating.

If you check out some videos of the world’s artistic skating championships and compare the overall look to that of Olympic figure skaters and you'll get an idea of how much harder it is. In terms of crossovers, cross-rolls, simple jumps, etc., I've found them to be only a little bit more effort when you are ice skating. But roller skating requires much more focus on inner thigh muscles to get the same level of control over moves. It's harder than figure ice skating because getting your feet to do what you want takes a bit more effort and muscle.