I learned how to ride a unicycle last year, it wasn't too difficult.
Would you say it requires more stability than a bicycle?
And a lot more balance, you need to lean with the movements.
Unicycle
A unicycle is a vehicle that touches the ground with only one wheel. The most common variation has a frame with a saddle, and has a pedal-driven direct drive. A two speed hub is commercially available for faster unicycling. Unicycling is practiced professionally in circuses, by street performers, in festivals, and as a hobby. Unicycles have also been used to create new sports such as unicycle hockey. In recent years, unicycles have also been used in mountain unicycling, an activity similar to mountain biking or
. Susan B. Anthony said, "Let me tell you what I think of bicycling. I think it has done more to emancipate women than anything else in the world. It gives women a feeling of freedom and self-reliance. I stand and rejoice every time I see a woman ride by on a wheel...the picture of free, untrammeled womanhood." 
In 1895 Frances Willard, the tightly laced president of the Women’s Christian Temperance Union, wrote a book called "How I Learned to Ride the Bicycle