I’ve had a professional bike fit done for my road bike. The ideal extension is a 15 degree angle, as in @JimT 's excellent illustration. Apparently at full extension your pelvis will rock from side to side.
So that’s the advice for bikes, I’d guess the ideal for unis is a bit lower.
Hi, Also 40+ years of heavy offroad cycle raceing, 60+ on uni/muni. Set it low, you need to ride the wheel, it’s not a bike so don’t think you can sit full weight on the seat (thats to stear with) just my years of riding and producing my own muni’s talking.
Lobbybopster
Yes please!
@Andy Remember, only supposed to brag about how good y’all are and how much y’all know!
Don’t never ask Thoughts?
Yah, see! They’ll come aplenty without ask’n.
I ride mainly rolling rather than bouncing: road, trail, paths, but not trials, hops, or drops. For many years I set my seat according to the road bike rule: leg almost straight at the bottom of the pedal stroke.
Just recently, I have experimented with lowering the seat on my 36 and my 29 to give a little bit more leg bend at the bottom of the pedal stroke. I have found it is far better.
You mean that on one trip you change the seat height when you come to hills? Isnt that too much trouble?
Personally I found that lowering the seat on the 36" made mounting a lot easier. Actually sawed a bit off the saddle pin. But the seat isnt so low that I get knee pain.
“Bike” is the important bit in this statement… On a bike fit you are fitted to the bike where your body balance point is in front of the bottom bracket. The fit works on the angle between the legs and body (depending on the bike, but between 105 and 115 degrees). Saddle height on bikes considers optimum power as well as hip rotating. Seat height effects the knee angle and the optimum power angle as you have a point where the knee has to be more bent than it does on a unicycle, that bent knee changes the way power is produced. Also remember you “sit” on a unicycle seat, where as you “perch” on a bike seat as you are distributing your weight between seat and arms.
I agree with the statements that the saddle can be too high on a unicycle and it causes the hip to move on the saddle which is not good… for road unicycling your saddle will be higher than the “fit” length on a bike. Muni is different as you are using your legs as a suspension so you need to have your saddle lower (at least at the back). The most common problem you see with unicycle road riding is riders who have the saddle too low, not too high.
The important thing on a unicycle is to be comfortable. One persons optimum height/leg angle will not be the same as someone else’s. It depends greatly on the riding technique and the body angle.
Please do not compare cadence on a bike to that on a unicycle, it is hardly relevant. Look at the foot speed. Road bike with a cadence of 87 doing 25mph has the same foot speed (1.57m/s) as a 36" unicycle with 100mm cranks at 149 cadence doing 16mph… if you ride both you can test this for your self in real life, they do feel similar.
36’er: As high as possible (it’s more fun), but still low enough so that I can (barely) get out of the saddle on climbs.
Muni: As high as possible (better balance), but still low enough so that I can do small (30-40 cm) drops without touching the seat when I land.
No, I don’t change the saddle height during a ride. I simple stand up and pedal with some space between the saddle and my butt for maximum power on steeper hills. In the photo above it is hard to see but there is likely a couple inches of space above the saddle.
My riding style has developed so that I support a lot of weight pushing down with my arms. To some extent, I am perched on the unicycle seat. My bar setup is low, and my saddle is high. I bend forward at the hips while riding. If my seat were lower, I might start standing up out of the saddle, which isn’t good, because my riding style requires that I maintain leverage with a solid connection with the seat. This allows me to push down and pull up on the bar ends without sliding the saddle forward and backward.
Every time I thought my saddle had gotten too high…and tried to lower it a bit, I was not happy with the results. However, something interesting happened recently. I tried my neighbor’s 20". He is shorter and has a lower seat. At first I rode out of the the seat and held on with one hand. But, then I sat down in the seat, it felt ridiculously low, but nevertheless I found I could ride in that position. But only, perhaps, because my balance had improved over time. As a novice, I probably would have struggled putting weight onto an overly low saddle.
As a beginner, I was influenced by an expert rider who rode with a high saddle and both hands on the bar ends. I worked as quickly as I could toward both those attributes, and I am happy with the results.
A dropper seat post, of course.
Your post reminds me of the joke about intolerant people. That they should lined up against a wall and shot. I don’t know where to draw the line between the open-minded and non-open-minded riders on this forum. Or if that line even exists. Maybe Jesus can help:
“If I alone bear witness about myself, my testimony is not true.” --John 5:31
“Even if I testify on my own behalf, my testimony is valid, for I know where I came from and where I am going. But you have no idea where I come from or where I am going.” --John 8:31
Eek! I’m thinking maybe you meant 20 – 30 mm? 
More of a hyperbole - to illustrate the point that even extremely large changes in seat height don’t add much danger 
I’m convinced, and I’m sorry I doubted you.
Finnspin, I thought you meant to say “20 or 30 inches higher.”
But seriously, there is plenty of risk as you sit higher. Do I have to say it? You fall harder. Especially tough on the older set who, with one notable exception on the West coast, are likely to be a good bit heavier than they used to be in their youth, and with weaker muscles than they used to have.
That’s why I like smaller wheels and longer cranks, you are practically dragging along the ground. Though I have to say that as I get in better shape, I am going for some extra height so as to increase pedaling efficiency.
At the risk of lowering the tone, I saw this on TV last night and it made me think of this thread… (apologies if you are not familiar with Family Guy).
In most cases, we are probably talking about a difference of an inch or two (25 – 50 mm) which makes negligible difference to how hard you fall. However, it may affect the likelihood of a fall.
Crank length is an important factor. Bikes typically have cranks of 170 mm or around 6.5 inches. That means that the bike industry has decided that an average adult can pedal efficiently with the feet turning in a circle of 13 inch diameter.
Most unicycles have cranks somewhere in the 110 mm to 150 mm range, giving a circle of diameter of around 8.5 to 10 inches.
So on a unicycle you are using only a part of your potential range of efficient movement. The question then is whether it is better to use the top, middle or bottom part of that range.
If you set your seat according to the road bike rule, you are using the bottom part of your potential range. I suspect that the middle part is more efficient.
The other difference is that a unicycle on the flat is generally high revs, low torque, whereas a bike is lower revs, more torque. You are using your muscles in a different way.
Therefore, the road bike rule can be no more than a starting point for unicyclists. The consensus seems to be that “a bit lower” is better on the road, and “quite a bit lower” off road, and “much lower” if you’re doing trials.
The other part of cadence is how much the legs have to flex to make a compete crank rotation. The higher the saddle the more the legs have to flex to make a crank rotation. I would guess there is some middle ground for maximum cadence.
If you look at foot speed, @johnfoss likely holds the record for maximum recorded foot speed on a uni. It is reported: “17.5 mph, John Foss, Max. indicated speed on 24” with 125mm". That calculates out to a cadence of 245 RPM or a foot speed of 631 ft/min (3.2 m/s)!
It would be interesting to hear from John about how high his saddle was compared to a full leg extension at that speed.
I don’t think those work for unicycles (speak up if you know otherwise); we put a lot of torque into our seats and I don’t know if dropper posts/clamps are built for that. In other words, your seat would be crooked a lot.
Absolutely. And this applies to Road as well as Muni. When you hit that bump in the pavement with your pedal at the bottom, you can get bounced off the seat, which takes your bottom foot off the pedal, which is bad. Plus, you’re slightly higher up at that point also! This also plays to the downside of suspension seat posts. In that situation, the same problem is magnified, as the bounce lifts you even higher! I speak from experience; a ThudBuster seat post on my old carbon Muni.
This probably depends on the type of riding. For Track, you definitely want the seat high for maximum foot speed with minimized flexing of the legs. But for less predictable surfaces, riding with your seat real high can be a problem, as mentioned above. I would add to your “bit” ratings:
Basically, it’s maximum height were your hips aren’t moving. What I used to call “crotch massage” for people riding with the seat too high. 
