sick creation I was going to comment it looks like a scooter with its handlebar chopped off. And then you added a handle at the end! But a troll scooter because the handle doesnt actually steer the front wheel XD
Great thread, and really great build! Iām just now pulling the parts together to build a very similar machine.
Years ago I built a cheesy rip-off of the Rip-Stick (which I call the Dip-Stick)ā¦ Then I more recently built this off-road electric mountain-boardā¦
Iāve been having a blast with it. But now Iāve decided I need to build a 2-wheeled electric board, and Iām finding videos and threads like this one.
Before pulling together my parts list, I wanted to experiment with steering geometry to make sure I wasnāt going to waste a ton of money and get nowhere. So I modified my āDip-Stickā so the rear-wheel doesnāt caster and the front one still does. To do it right, I should also add structure so the board doesnāt articulate in the middle - but I didnāt bother. I did however mount my front caster flat to the bottom of the board deck.
I then tried riding it with a simple push, and then holding onto my wifeās car. I was pretty surprised that it seemed very unstable. After remounting the caster as it had been on the Dip-Stick it became super-tame and rideable.
The reason I mention this is because the angle of the caster is opposite of what Iām seeing on some of these 2-wheeled boards. It looks like the board in this thread has its castering axis positioned forward (i.e. the bottom of the pivot axis is forward of the top). Mine is the other way around. The bottom is well behind the top (maybe 20 deg?).
If you think about a bike, it has effectively a reversed caster on the front wheel. In other words, the axle is in front of the pivot axis. Additionally, the pivot axis is slanted forward as it is on the board on this thread.
But our wheels are castering in the traditional manner - not like a bike. Ours caster like the wheels on a shopping cart - the wheel axle is behind the pivot axis. Perhaps thatās why my mutant Dip-Stick became so tame when I also gave it the opposite slant to the castering axis.
Now, thereās every possibility you guys have done all the math and experimentation already. Iām just going by my little experiments being pulled by my wifeās car. Once I set the caster axis backward I could easily hang back and carve turns - until the urethane came off the rollerblade wheel.
Now I have to decide whether to make a reasonably nice steering system like you guys did, or first rough something out and play with the geometry until Iām really liking it.
Any thoughts would be appreciated.
I think Iām going to write a simple program that will let me enter the linkage lengths and to simulate how it affects the caster. Moving the mouse left-right will control the steering. Iāll post some results here.
Iāve written the program to simulate the steering geometry. Itās quite basic, but I think it does what I need. I can change the lengths of the links and the spacing of the pivot points. By moving the mouse I can see how it steers, which gives me an idea of the caster point (and how that point moves).
Hereās a screen-grab, and hopefully the link will allow you to see a several second animation.
https://www.dropbox.com/s/y382gska7ytmcs5/Steering%20Animation.mp4?dl=0
Having thought some more about the problem, and consistent with my experiment the other day, I feel confident that canting the pivot axis backward (bottom of axis is aft) rather than forward, should add significant stability. In this configuration, steering the wheel in either direction will raise the board a bit. While canting it forward would have the result of lowering the board when steering the wheel off center.
Iāll post results here when I make a (probably rough) working model.
@spork Are you still building your 2 wheel board? I"ve been building a 2 wheel based on the āspeedboardā from kickstarter. Mine isnāt any easier to steer, iāve started playing with the caster angle. and the steering did improve a bit when i pitched it up. i will have to pitch it down next.
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Sorry I missed this. Yup. Still working on mine. Iāve got the frame and steering pretty nearly done. Iāve gone with a single-point caster and may later change to a mechanism more like the SpeedBoard.
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I did a stability test last night. I attached a luggage strap to the tie-down hook of my wifeās car and she pulled me around. The steering and stability felt really good. Next is adding the motor, drive-train, batteriesā¦
Just got my board ready enough for its first low-speed test ride. Still plenty of things to do to it, but itās off to a pretty good start.
After this video I reduced the rake angle of the front-wheel pivot by a few degrees primarily because it didnāt have as much lean as Iād like before dragging the steering frame. That change gave me a significant improvement in lean angle and also had another predicted effect. It made steering a little more nimble and a little less stable. But all in all it still feels quite stable to me.
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hey @spork, love the look of this thing, what should i call a two wheel board like this? do they have a generic name yet?
Have you seen the āspeedboardā https://www.kickstarter.com/projects/innodave/speedboard-the-30mph-two-wheel-electric-skateboard
p.s. you should definitely create your own build thread and document this build from start to finish
Hey, nice build! I was away from this forum for quite some time. This kind of board gets quite some to get used to but after that itās quite pleasant to ride. I just advise you two things, wrist guards, and full face helmet.
I abandoned my plan to convert mine into a scooter and it sits in my garage unused without a battery. If anyone is interested I can sell it with all of the stuff I have for it, just PM me.
Not sure if thereās a generic name for these. I have seen the SpeedBoard. Iād been thinking of making one of these, and when I saw the SpeedBoard I realized I had no choice.
you should definitely create your own build thread and document this build from start to finish
Perhaps Iāll do that. I kind of thought people didnāt like to have new threads when there is already a thread on the topic.
I think most anyone could just hop on this one and go. I played with the steering geometry on a little wooden board before making this one. By raking the steering pivot you can make it quite stable. After this video I actually reduced the rake a bit to make the steering a little more nimble (and the stability a little less).
So what caster angle did you end up with? I went with 15 degrees if I recall correctly.
Iāll have to check mine. I think I ended up between 20 and 25 deg. But yours uses a steering geometry more like the Speedboard if I recall correctly. I wanted to go that same route, but my calculations showed that castering that geometry would likely not work as well.
actually the opposite, its much neater to have your own individual thread specific to what you are doing. it makes it much easier to share your stuff with others as you have a direct link with all your build details on display
your board still running?
Like I mentioned it doesnāt have battery at this moment, which ended up being used in my longboard that I revived today because old battery failed. After a nasty crash which ended up with 3 fractured forearm bones and like 15 screws later I decided to not ride it in this form 
I had a plan to convert it into scooter but it would be easier to build scooter from scratch. I feel safer on my trampa mountainboard riding forest pathsā¦ so letās say that Iām done casterboarding. For ever.
ah ha! now i know what to call these weapons
would you say casterboards are generally more dangerous than traditional esk8?
if so, is it due to the steering & balance skillset required?
I canāt speak for other designs, but mine feels very much like my 4-wheeled board. Yesterday a buddy tried it and was riding within a couple of minutes. The only problem he had at all was that he was initially being so extremely cautious about applying power, that we was getting false starts until he gave it enough juice to actually make it go. As soon as he did, he just rode off, turned around at the end of the road and continued back.