I’ve debated the dynamics of this in the "unibokk Long rider thread.
I can only say that this set up feels more stable and comfortable than having the length of everything stretching out in front of the seat post.
Your photo shopped version is interesting. It reminds me of the hatchet uni.
Yep. You make a good point there. It’s something I considered and may yet do.
Exactly what I was thinking seeing this - in fact moving the saddle backwards and forwards on the seatpost results in exactly the same effect as rotating it on the seatpost. Given the handlebar is attached to the front of the saddle in the normal place, then exactly the same relationship between the unicycle, saddle and handlebar could be achieved with the seatpost in the usual place. Any perceived difference is purely imaginary.
…hmm, and having found the long rider thread, it appears we’ve already had this discussion
Ok, let me give a simple explanation,
The handle bar extension (boom) generates torque, (i.e. leverage).
The further it extends out from the seat post the more torque/leverage, it generates, just like a long crank on it’s axle.
This extra torque/ leverage, puts considerable stress on my arms as I have to react to bumps and rolls etc.
However, by shifting the saddle backwards I am effectively shortening the front boom, thus reducing the torque effect on my arms, whilst still allowing a long riding position.
I suggest you guys make a long rider with the saddle shifted back and try it for yourselves. 
The torque works the other way - a longer handle bar means your arms have more leverage on the bumps, not the other way around. It’s more stable with a longer bar.
It works the same way that longer cranks give you more leverage on the wheel, and shorter cranks give the wheel more leverage on you.
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And I don’t understand how moving the seatpost connection affects how long a bar extension you use. You can choose whatever handlebar length you want, no matter where you decide to attach your seat.
I mean, it’s a cool project, and it’s great that you ended up with something you like, but it’s not working out for the reasons you think it is.
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You should check out Turtle’s V unicycle for comparison - he ends up with a similar extended riding position using almost the opposite concept, by moving the seatpost backwards instead of forwards.
If we consider saddle and handle as one solid unit, the seat post should be in the following position for minimum flex:
The ration of the distance between seatpost and seat to the distance between the seatpost to the handle should be the reverse of the ration of the weight you put on the saddle to the weight you put on the handle.
PS: Nice Project! Could you please post a detail pic of how you attached the seat to the post?
@ MrImpossible
When I began using handlebars. I learnt on a grassy trail. I found that with every bump my arms were being thrown left and right and I couldn’t control it.
So I decided to shorten the handlebars and found that my arms weren’t being thrown about as much.
Over time I moved onto the cycle path using the handlebars at full length.
But even now if I’m going on rough terrain, I use much shorter handlebars.
I have checked out Turtles V frame before and just like my idea the V frame effectively shifts the saddle back, aft of the axle. This allows the rider to lean forward more whilst his body’s centre of gravity is more directly over where the axle is, resulting in the rider having to make less, correction of balance, moves.
Moving the seat post connection doesn’t alter the overall length but it increases the length aft of the seat post.
@ Eric aus Chemnitz
Thanks Eric. I’ve just been reading your post. Your explanation sounds good to me. 
I will post some detailed photos soon.
Yes, definitely interesting. As has been pointed out, it is the relative position that is important and not where it is connected… but I do like this. There are quite a few broken zero saddles about and this would bring them back in to use. Also… you could make the saddle so it does actually flex! I think that could work well with the handle being solid and a little vertical flex on the saddle. What do you think?
One thing I am working on is looking at cycling position created during a dynamic fitting for a bike frame. This data, along with a calculation on the bodies centre of mass (my guess is that this should be directly above the hub) should produce some interesting data. I will feed here when I have some diagrams.
Roger
Which is the only difference the seatpost position makes, and the only advantage of moving it - yet flex isn’t something being mentioned by unibokk as an issue. The advantages he is mentioning are all achieved simply by tilting the saddle forwards with a normal seatpost position and then rotating the whole unicycle bckwards around the hub.
Thanks Roger 
Yep, vertical flex sounds great. It may pave the way for lighter and less bulky tyres and allow for higher psi tyres whilst still comfortable on the lower back.
I have some photos of how I assembled the Retro. I’ll try and post them today.
Hello Aracer
I am not an engineer, I am just an enthusiast who is always searching for improvement, especially for long distance riding.
But, as always I do enjoy debating with you.
Thanks for your contribution.
The photos
1, Shows the original housing for the internal rotating block and the new narrowed rotational block moved forward into its new position.
2&3, Show the new toothed saddle to post grip, the new reduced rotational block and the hex saddle securing bolt.
4, The toothed saddle to post grip before I thinned it with a hacksaw. I took this from a spare saddle bar which I had previously bought for my 36" Night Rider uni.
5,The saddle with the new rotational block housing carved out.
6,The bolt and rotational block being put into new housing groove.
7,The old toothed grip to the right and the new toothed grip on the left of the photo.
8, The new forward toothed grip mechanism securing the seat to the toothed seat post
Wherever you put the saddle, the only way to ride the uni is with your centre of mass in the correct position over the wheel. Therefore, if you move the saddle back relative to the frame, you need to tilt the frame forward to get your centre of mass into the right position. There is no change except for the tiny difference made by the weight of the frame being in a different place.
However, if you put bars on in such a way that your torso is tilted forwards, your centre of mass moves forwards and therefore your saddle ends up further back than would otherwise be the case.
This has two potential advantages:
Your legs and core muscles are nearer to the ideal pedalling position, as per a conventional road bike.
You are more aerodynamic.
So, if you change the position of the saddle alone there are no real difference.
However, if you add long bars you move the effective position of the saddle backwards. Of course, you then need to adjust the tilt of the saddle (nose down a bit) to compensate for the new position.
From a strength point of view, I’d rather have the saddle fitted to a normal seat post in the normal way, and use a long handle bar extension.
However, from a pleasure point of view, the more my uni resembles a bike, the less I enjoy it. I like sitting more or less upright on a uni. Personal preference.
@ Mikefule
The new adjusted set up is not as strong as the Zero in its original state so I might reinforce it as suggested by UniDreamerFR.
Notice that I left the original toothed (saddle to post) grip, in place. I didn’t want to compromise the saddle structure, too much by removing it.
People keep telling me that the lateral saddle position is not relevant but the uni feels more stable with the saddle moved back. I would like to see other riders experiment with this idea. I’m going to get an aluminium beam made which will afford an even longer reach.
Having the saddle mounted in it’s traditional position on the post would require a longer T-bar than the current KH t-bar to achieve such a long reach.
I agree with you that the upright posture is more fun, but only on shorter journeys in my opinion.
The bike position has it’s advantages but it is a bit too “down to business” in some ways.
I had been thinking about the range of possible seatpost positions - instead of the post under the seat, with the handlebars sticking out in front, you could have the post connected to the handlebars, with the seat on a long extension backwards. It would be like the old softride bikes. Maximum seat flex!
I think it could work, though I’m not sure what would happen when you stood up… maybe you would need some front-of-the-saddle handle to hold when standing.
You have the T bar mounted to the saddle in the standard place, so the distance between the saddle and the bars is exactly the same however the seatpost attaches to the saddle.
Ah! Aracer. If only you would read more slowly.
I am referring to a beam unicycle which would afford an even longer reach than the KH t-bar set up 
