The second seat would probably look very strange. I also wouldn’t want to add that much more weight to my uni. I think one very adjustable bike seat should be sufficient for road riding.
Here’s a unicyclist afraid of looking strange.
Well alright, I guess we already look pretty strange to all non unicyclists, but what I mean is I wouldn’t like the looks of two seats behind each other.
munirocks you might be thinking of a “banana bike” seat which as I recall was probably as long as two seats end to end. I had one as a kid, they were pretty cool as it was really easy to do wheelie’s on. So perhaps a “t-frame” but with a really long seat mounted on top of the “T”.
Hmm, yeah I might try that some time. But for now I’m pretty satisfied with my current bike seat setup.
“V” Frame Specs
Although I am the owner of Florian Green I am not the builder of it. Here’s what I can tell you: The angle of the “V” on my frame is about 25 degrees. It’s a little difficult to measure because the tubes bend a little as they near the bearing holders. At the top of the tubes (where they go over the tire) the separation between them is about 23 1/2 cm which is just over 9 inches (center to center).
My seat and head tubes point directly to the center of the hub. They are not perpendicular to the ground or pointing anywhere else. If the head tube were to be perpendicular to the ground that would angle it back towards the seat. You would lose out on a little forward reach that way.
I don’t think there would be any benefit to reducing the angle of the “V” frame. Frame flex is not an issue. This is a sturdy guni. If you reduced the angle then you would have a head tube that is quite close to the seat. Your handle bars would mount right in front of your seat and you would lose out on the great benefit of the “V” frame, which is to have strong handlebars that are farther out in front of you than a T7.
Keep in mind that the front frame tube (from the hub, up over the tire and back down to the hub) is in the neighborhood of your knees. If you increase the angle of the “V” it may interfere with your knees more, maybe not. This is a difficult issue to find the perfect solution for. It’s not a terribly important issue, it’s just a little tricky, that’s all. As long as I don’t tuck my knees in toward the center I’m just fine. I don’t notice any limitations when I’m riding, now. I just remember that when I first started riding it last year I would occasionally knock my knees on the front tube. Increasing the angle to say 30 degrees would change where that bar crosses the path of my knees when I’m pedaling. As long as I keep my knees a few millimeters out of the plane of the front frame tube, I’m fine.
I really like Pete’s handlebar set up. I can adjust the whole thing up or down. I can also adjust the angle of the aero bars. The only thing I can’t adjust is its fore/aft position, but I don’t have any problem with that.
Here is the link to Pete’s trading post thread for the Florian Green. He gives some details of construction in it and pics.
Hope this helps.
I agree that the current Nimbus 36" with its backwards V frame is wasted. Bringing the rear tube around to the front and increasing the angle is the way to go. That is exactly what Pete did when he made Florian Green. He needed another tube to mount the seat (I think he used the original seat tube to mount the handlebars). He welded some rods to connect the front and rear frame tubes. Most of the other parts (handle bars excepted) were cannibalized from the original Nimbus 36". Check out the above-posted trading post link for more details on construction.
I’m not sure how much my frame alone weighs, but Pete weighed in the whole guni at 18.9 pounds with Schlumpf, I’ve weighed it at around 19 pounds, give or take, on my scale at home. About a fifth of that is tire. The Schlumpf, of course, accounts for a few more pounds. I wish I had weighed it when I took it apart a few months ago. I remember the frame being surprisingly light. More than that I can’t tell you.
This brings up the issue though of tire weight. If we really want to lighten our 36"ers never mind the frame, we’ve got to find a skinnier tire! I talked to a bike tire sales representative a few months ago. I asked him what it would take to get a skinnier 36" tire. He said “an order of about 1000 tires. If you went to India, you might be able to get a tire into fabrication with an order as low as 500.” So if we each commit to buying ten tires and send someone to India… Hey Ken, know anyone going to India any time soon???
I’m not sure. You could ask this lot: www.induni.adventureunicyclist.com
I believe they still have a couple of places handy
Klaas Bil, I must say that if I am compelled to take sides on this argument (well, let’s just call it a discussion, shall we?:)) I have to side with Ken. A lower center of gravity is an inherently more stable position. Aside from instinctively tucking when I’m riding fast I did my own little experiment after you proposed the broomstick/pencil analogy. The issue is not comparing a broomstick to a pencil to half a pencil and seeing which one is easier to balance on your finger. The issue is if you have a ten pound broomstick is it easier to balance it on your finger if the weight is on the top or the bottom of the broomstick. I looked around my house and found something like a ten pound broom stick with a sharp edge. In my basement I have a splitting maul ( you know, a really fat axe). I balanced it on my fingers with the head of the maul at the top and then balanced it with the head at the bottom. It was definitely more stable when the head was on my fingertips. Less weight way up there picking up momentum every time it got a little out of balance. Smaller, less energy-consuming corrections with the head at the bottom. (Kids, try this at home ;))
What does this mean for unicycle designs? Well, the upside down T7 prototype has the advantage of lowering the rider’s center of gravity. The lower you can have the seat and the handlebars the more stable you are, as long as the rider has enough postural maneuverability to maintain balance and his or her legs can extend properly for pedaling with maximum force. If you can mount the seat and handlebars on an arc around the wheel with the seat post in the center being higher than they are, then that is a very stable configuration. Stretching the handle bars way out front while keeping them low is a worthy goal. Of course, I think the new T frame configuration is inherently weak and it gives me the willies. But this is all part of the grand uni handlebar experiment and I’m happy to say that I enjoy not being one of the lab rats.
Wouldn’t it be nice to know enough about unicycling to be able to get a professional uni fitting? You’d think that something as simple as one wheel would be rather straight forward, wouldn’t you? Some things are certain though. As you go faster and you lean your upper body farther forward your seat must move backwards behind the hub in order that your center of gravity continues to average out directly above the hub.
As for “the little bump on the front of your knee” (if you’re referring to the knee cap, that’s the patella. If you’re referring to the little bump just below that, it’s the tibial tuberosity.) being directly above the pedal axle, seat height and leg extension will make a big difference there, as will tuck position which effectively moves the seat back. But crank length will also affect that.
Unlike the bicyclists, we are still at the stage of “Gee wiz, that feels about right to me.” Experiments like this will go a long way to figuring out the best configurations given speed, terrain, and body proportions.
I intentionally lean forward and tuck to get less drag. Past 15 mph it seems to start having a major effect. That’s about 25km (stupid USA needs to get on the metric bandwagon).
I’m also interested in experimenting with V frames and long handlebars. I may work on some ideas this weekend. I have two defunct Nimbus 36 frames that I’m going to make into one V-frame (requires new bearing holders…).
Note that the tubing on the Nimbus 36 is NOT very strong. I was looking at my old frame last weekend, and the front tubes have a large crack in them (at the top, before the bend), and it probably wouldn’t have been long before they snapped! I need to take pics and warn others about the potential problem.
I think you’re right. You can figure that drag (= air resistance) must make a difference. Personally I have experienced that around that speed, even a slight tailwind increases my cruising speed. I would be surprised if others have not found this. By the same token, somewhat less drag would increase my cruising speed, because decreasing air resistance is all that the tailwind does.
Cracks in the frame? I hope that won’t happen to mine… And you’re gonna use it for a v-frame anyways? Sounds dangerous.
I wonder if it’s a good idea to flip my nimbus frame around. Maybe the forces would be distributed more evenly between the two sets of tubes then… It wouldn’t look very good though. But I think it might make sense. The way it is now the frame technically gets torn apart, while if I turned it around it would rather be compressed, right? Any thoughts about that?
I don’t think that’s strictly true, your centre of gravity (technically centre of mass) must always be slightly ahead of the contact patch of the tyre otherwise you fall off the back of the unicycle.
I agree that as most people accelerate and lean forwards their seat moves backwards but the net movement of centre of mass is forwards.
My theory is that the reasons people tuck are varied, partly stability, partly drag, and partly moving their centre of mass forward in a stable and comfortable way.
I’m referring to the tibial tuberosity.
I agree that seat height, leg extension, tuck position, and crank length will affect this, what interests me is whether there is an advantage in setting up a unicycle so that when the rider is tucked down and cruising on the flat they end up with their tibial tuberosity over the pedal axle at the front of the stroke. It can never be as precise as the position on a bike (for obvious reasons!) but it might be advantageous to get as close to this as possible both in terms of efficiency/power and in reducing overuse type injuries.
Definitely. It’s all good stuff
I’m not arguing that…that’s why drafting works.
But I think it’s still more important to get in a position with the most power and stability.
Paul, I don’t want to get mired in tangential technicalities, but the way I see it, the only time that my center of gravity/mass is ahead of my hub/contact patch is when I am actively accelerating. During this acceleration I put my weight forward and make my wheel catch up. Once my speed has stabilized then the center of gravity/mass should return to being directly above the hub/contact patch. If my center of mass was in front of the hub how could I not fall forward if I am not accelerating? This is getting curiouser and curiouser. Have I been breaking the laws (of Newtonian physics) all my life?
add drag/air resistance to your equation and you will find that the rider needs to have their center of gravity slightly forward and pedaling with slight thrust to counter the drag forces to stay balanced at a steady speed.
WOW! That took FOREVER to read. Ken you just blew my mind! This is exactly what I’ve been trying to put into words for a long time.
Nothing a little hack-sawing couldn’t fix (seriously though, I’ve done it, though not with a KH post)
Thanks, once some of the snow melts here, I’m going to try this (with my drop bars of course). They were amazing during RTL, just too close to my body.
I agree that the handlebar sometimes makes bumps worse, and for Coker MUni, I haven’t used a handlebar on the few rides that I’ve been on and I wouldn’t use it either.
Yeah, especially for track races where your cadence is crazy for the crank size, you have to lean forward a lot, though sometimes you lean too far forward. I have NEVER fallen backwards while sprinting (or even going fast for that matter).
Ken, thanks for this light bulb idea, it makes me wish that I knew how to weld.
I owe you an apology. You are completely correct. I’d not properly thought through what happens when velocity is constant* - it’s a bit of a school boy error on my part :o
*ignoring drag, head/tail winds and friction.