First advice, learn on a trails uni. The fat tyre and long cranks make them far easier control than the average learner’s uni with a skinny tyre and 114 mm cranks (effectively a freestyle uni).
Note that nearly everything about an experienced rider’s technique does not apply to a beginner. Many experienced riders offer inappropriate advice because they tell you what they do now. If they can still remember how they started out they offer what they think helped them to learn, not realising that there were better ways.
Learners should have the saddle lower than an experienced rider so that they can just touch the ground. This helps avoid the precarious feeling and building up momentum as you fall to the side and avoids putting too much the weight on the saddle.
Putting weight onto the saddle is something to work towards as soon as you can but not right at the start. Until you get basic control of the unicycle, putting weight on the saddle tends to make it unstable.
Keep your weight on the pedals and grip the front half of the saddle between the thighs. This puts the weight down lower and is much more stable. If the saddle is too low the thighs can’t grip properly because they move too much. Use this as your minimum height guide.
Spend only enough time holding onto a fence to get a feel and learn how to point the wheel where you want to go by twisting. This should only require a few minutes. Then get away from the fence because fences inhibit the fundamental action that maintains an upright position, steering the uni in the direction of your fall.
Use this mantra. “Put the wheel where you would put your foot if you were walking.” Walking is a continuously saved fall. So is unicycling. Your brain knows how to walk and can employ the same neural pathways to ride.
Forwards/backwards balance is often described as continually adjusting forwards and backwards pedal pressure. It should not be thought about in this way but as pedalling forwards enough to keep up with the fall. It is less about F/B balance than the avoidance of actions and geometry that cause oscillation between forward and backwards leans.
The most prevalent and unhelpful unicycling myth suggests the unicycle needs to be treated as an extension of the rider’s spine and kept upright. It fact an upright unicycle is extremely unstable and prone to oscillation. The unicycle should slope backwards while the rider leans slightly forward to keep their centre of mass above the wheel’s contact point with the ground. This geometry suppresses oscillation and stabilises steering by inducing “trail”.
I encourage the use of a backstop start. Put one foot on the back pedal to push the wheel back against the stop, then step up to the other pedal. Experiment with back pedal between 4 to 5 o’clock for a left foot start (or 7 to 8 for the right foot). Alternatively, use a support to get into position. However the backstop start is a step towards achieving a static free mount.
As you take off, lean both you and your uni much further than you are likely to expect so you will get momentum into your body. (At this point only does the uni actually lean forward.) Start pedalling quickly to bring the wheel up to speed and into the normal riding position with the uni leaning slightly back.
This take off technique avoids the problem of riding slowly, which is not a beginner’s skill. It also reduces the likelihood of falling backwards which is about the worst thing that can happen.
On each attempt, focus on nailing one aspect. Forwards, sideways, getting over the dead zone when the cranks are vertical etc. Ultimately all the skills will come together and you will be able to ride.
Begin your learning on a slightly downhill soft grassed area that is as smooth as you can find. Holes and lumps are hard to deal with. The down hill slope helps overcome the resistance of the grass. Grass is better to fall on while you learn to run out of an aborted attempt. It also slows everything down and dampens overcompensation.
As soon as you can ride a few wobbly turns and are comfortable with emergency dismounts, move onto a flat hard surface. Put some protective gear on, especially wrist guards.
My learners have averaged about an hour to reach a point where they can ride ten metres on a trials uni using these techniques. Of course I was there to give constant advice on refinements. Your experience may vary, especially if you are on a freestyle uni.