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:
- A bit lower for Road riding (some bumps)
- Lower than that for dirt riding (more bumps)
- Even lower for really rough surfaces
- Several notches lower for Street/Trials, so your legs can be jumping and landing tools
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.