post your homemade handlebars here!

“Spline-bar”

Just want to share my “spline-Bar” with All the creative minds on the forum, hoping to get some input and ideas.

I’m a Mechanical engineer, and have access to a manufacturing facility that allows me water-jet and lazer cutting, milling ,turning ,etc. So, there are no limitations there.

What I’m presenting is mostly a “jig” that would allow me to play around with different riding positions. Future versions will be optimized by functionality and weight.

Notice the concept includes adjustment on the angular position of the seat post, in a way that doesn’t affect the pedal to seat distance.
Wide range for aero bar position adjustment on the front section would allow me relative adjustment for weight balance.

I will report soon about the “riding” experience on it…

Erich

myaerobars.bmp (253 KB)

sick, man. maybe i should switch to mechanical engineering…

That is a thing of beauty! Looks very cool.

“Adjustment on the angular position for the seat post” doesn’t really mean that, though: if you think you shift your seat post forward in the spline bar, really what you’re doing is rotating the whole thing back with respect to the seat. I.e., the whole frame will assume a more backward orientation, such that in the end your centre of gravity is still above the wheel (or really slightly ahead of it, in order to keep riding).
The weakest point I see is where the “spline bar” is attached to the frame. There’s quite a moment acting on that point, with most of your weight on the seat which is some 20 cm backwards from that point. It might bend/brake the top of your frame? Of course, it depends on how much weight you put on the handlebars. My two points combined lead me to the suggestion to consider shifting your seat post forward, and your handlebar contraption by about the same amount. If the attachment to the frame were a hinge (not recommended!), the spline bar should be in balance when you are in your general riding position. But maybe you have it there already, it depends on how much you lean on your handlebar.

Interesting! I have been thinking about fork rake lately, and if it plays any important role. When I roll the 36er beside me it is easy to feel the increased stability of a lower fork angle (just as with bikes). If you place the saddle further back, the angle will become steeper and if the analogy with the bike is adequate, the unicycle would become more nervous and twitchy.

I don’t think the analogy is adequate. The front fork of a bike is forced to rotate around its axis which is non-vertical, and so if you rotate it, you lift the front side of the bike up. That provides the tendency for the front wheel to be in line (straight). Not so with the unicycle frame, it has more degrees of freedom since there is no movement-constraining rest-of-the-frame. If you twitch or steer a unicycle, you mostly rotate around the line from contact point to centre of grativy, and this is a vertical line. Rotation therefore does not lift anything and hence the system is not inherently stable in the way a bike is.

P.S. If you roll the uni beside you and have the frame at an angle, you may constrain the turning to be around the frame axle. Indeed that will provide some sort of stability, but it is different from the riding situation.

fantastic!

how does it feel :thinking:

Why would you offset the saddle so far behind the seat post tube?

I agree with your analysis, Klaas. But I still have a feeling that if the angle is not so steep it somehow will be easier for the wheel to roll over obstacles. I know the angle doesn’t affect the cog but it will perhaps make the force more horizontal. Tja …

As an afterthought, it occurred to me that the seat tube (part of the frame accepting the seat post) is designed to be clamped around something. So maybe to make it stronger, you should insert a “dummy” seat post short enough to not extend beyond the frame. But maybe you have that already, I can’t see on your picture.

Yes, like maybe the seatpost with saddle attached to it? :stuck_out_tongue: :roll_eyes:

Erich,
This is a brilliant new approach to frame design. You have opened up many new possibilities for adjustability. This design also allows for a relatively close position of the seat and wheel, making it possible for shorter riders to enjoy the benefits of a 36er with aerobars. (similar to Brycer’s “midget frame”)
I can’t wait to read a ride report.

Geoff

I will be doing some long rides on my 29er, so I wanted a handle of some kind, but nowhere near as long as a standard 36er handle. So I used a stoker stem, cut down a bit, attached to my seatpost and simply put my kh handle in that. It’s short and works well and very rigid since it’s attached to the seat post.

With this method I can easily remove the the stoker, which holds everything, and put the brake right back on the mount which remains under the saddle. Having the handle a bit below the lift handle also gives me the option of using both, since there is ample space between them. Of course, this set up will only be used for distance riding, not technical trails.

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Erich – that is great! What thickness material are you using? I like the design and idea, and I’m curious about trying it myself. Personally, I think I’d prefer if the whole thing was an upside down half moon.

corbin

Yes Geoff, I think Erich may be a fellow “friend of the midgets” with that seat set so down-low. Oh man, It is inspiring to see that designing a 36er unicycle for the half-lings of the world is not dead and Erich is taking up the cause.

This inspires me to finish my semi-serious video of a 4’7" rider on the midget 36er.

On a more serious note, I used a less sophistocated test dummy to test different amounts of seat “set-back” with aero bars - and found that around 7" setback was ideal for the aero bar set-up for riding centuries and a more modest 3-4" setback felt about right for a more upright riding position similar to that of a T-7 bar. I really like the set-back saddle mojo and feel like it makes my 36er easier to steer than the old “seat on top of frame” set-up. I did find that the un-braced T-frame like Erich’s really needed a brace to reduce flex when you put weight on the bars, but maybe he has this problem licked with all that laser cut, formed, welded and milled bit of wonderful??.

(In contrast, I think the midget 36er set-back was like 10" or so).

Brycer

Certainly seems like Erich’s design has no up-and-down flex, and, further, that’s the only flex possible, right?

For taller riders who’d want the same set-up, the central clamping mechanism could be changed to clamp a seat post, rather than frame. I love it, Erich, simple and elegant.

Questions:

  • What’s the weight of the frame and clamps part?
  • And without wanting to step into the “you should market that” argument, how much do you think they would cost to make?

Thanks for your words…Let me elaborate a little more on the concept. I have already a setup with just an improvised mast and aero bars mounted on it, and a bike seat. Everything works just fine…but I feel like my ride could improve if I could offset the seat toward the back; one option is just moving the aero bars more toward the front and as you said, the fork will incline backwards. However when that happens, that also changed the angle of the seat relative to the horizontal to a point where I couldn’t get a comfortable ride on it. So I decided to pursue a different approach. The angular offset allow me to use the seat post & articulation and the bike seat on design conditions; seat post around 72 degrees . Also, this angle happen to be the most efficient pedaling seat to hub angular definition in a bike, and that angle is what I used to define the extend of the adjustment slots. Finally , if I do get to ride with a vertical fork, or Unicycle frame, I should have no torsion on the bar/frame join.

I’m trying to maintain both, the fork/frame in a vertical position, and the adjustment of the seat independent from the first.

This is one of those things that goes with different peoples preferences. I notice you haven’t buy into aero-bars. And I congratulate you for having done recently your first Century without one.

My experience and preference IS for aero-bars and bike seat for long distance. Once I got the weight balance between saddle and aero-bars for the first time, I decided no going back to “vertical riding”. I can ride much longer now, and my hands do net get tired and cramped with the short handles my Coker came with.

I’m not positive yet , to how much offset I’m really going to use, hence the slots.

Anyhow, I’ll appreciate any input from you…I’m your fan number one!!!

I does have a dummy seat post to keep the seat tube from collapsing…look close-up picture. The dummy has some thick wall on top so it doesn’t fall inside the seat tube, and so that is not dangerous for the rider.

Very good call anyway…keep it coming please!!!

Thanks for your words…

…and Yes…I probably am on the midget class…I’m 5’ 5". In fact I bought my coker thanks to this forum…and after getting needed encouragement went I read that people could actually trim the frame and use extra something on their tennis. And so I did.

Picture shows how I look beside Claude Marguson last year at the Seagull century. Notice my “special tennis” ( two pairs of cheap wallmart flip-flops and glue).

So, yes this open the door to the rest of the midget unicycling community, but also could be used by taller rider, with a longer seat post , as any other unicycle.

Erich

Thanks ebevensee! It’s kinda like the “V” frame, but without the “V”! It’s really a brilliant piece of engineering. Would you consider selling them? Btw, I may have missed you mentioning it, but how much does it weigh? Is it all aluminum?