Ok guys. i’ve been a fountain of ideas lately.
i’ve decided to release my concept frames, and i need a few questions answered.
-Most of these frames are designed around the same type/thickness of metal as the hunter frames, round steel, etc. what type of metal rod/tubing are these made from? is it hollow or solid?
-What is(are) the most common width(s)for a(most) seatpost(s)
-what kind of tubing do i use for a seatpost holder? what kind of steel tube has the inner diameter of said most common seat post width?
and having these questions asked, here are my designs.:
–the “Flow” frame. either going to be made as a trials or muni… depending on popular vote and how well it works in reality
–The “Pricker” frame. Named for obvious reasons, the little spike thing points backwards. I’m not sure if it’s going to be so pointy, but it’ll be in that general shape. Probably for muni, because of pointy thing and won’t be safe for trials riding with all those unispins y’all are doing.
–The “DNAA” frame. Named partly for the DNA shape, and partly for my last name (hey, i have to name my frame after me somehow…) probably the most practical, and will most likely be made first because of simplicity. probably for both trials and muni… depending.
I’m nowhere near the most qualified person to answer these questions, but I’ll tell what I at least think I know…
-Most of these frames are designed around the same type/thickness of metal as the hunter frames, round steel, etc. what type of metal rod/tubing are these made from? is it hollow or solid?
4130 Chromoly tubing for most, always hollow. Some frames are 4140, some aluminium.
-What is(are) the most common width(s)for a(most) seatpost(s)
Standard cheap unicycles are mostly 22.2mm diameter. 25.4mm is the smallest of the common sizes for the higher end unicycles I think. 27.something is another. Someone else can help out here.
-what kind of tubing do i use for a seatpost holder? what kind of steel tube has the inner diameter of said most common seat post width?
Usually you can find anything to match the seatpost size you want, since it’s just round tubing. My personal belief is that most frames go overkill with tubing thickness. My custom frame is going to be thinner and pretty light…and lots of fun. A muni riding friend of mine is making one for each of us. There’s a thread on it here - Custom muni project... - see the “future” project.
and having these questions asked, here are my designs.:
They didn’t show up for me, I’m very keen to see them. I love custom frames.
The Hunter frame is made from standard steel (chromoly) bicycle tubing. It’s standard bicycle tubing used for seat stays. Look at the some of Hunter’s bikes, like the cross bike, and you’ll see that he’s borrowing tubing and designs from his bikes to make his unicycle frames. It’s a good idea because he can get quality tubing and the manufacturing techniques are the same as what he does for the bikes.
Most other unicycle frames are made from other types of tubing. I think the Hunter is one of the few (only?) that is using bicycle tubing.
The ‘flow’ frame looks pretty cool, if it’s as I see it in my head - are these side-on views? I’d love to see pictures of some of these when they actually get built, they look pretty radical.
john childs: woot, you got your full guinness back!
well… um, i have yet to learn how to draw CAD…
but i’ll try my best… its a realy clear picture in my head, its just hard to make it look JUST right on paper or a computer… i might be able to draw it and scan it into the compy tomorrow…
Be sure to consider how the geometry of the frame tubing is such that it makes the frame stiff rather than flexy. The Hunter works because the frame tubing forms a wide triangle which is stiffer than if the two tubes are closer together, like in the Vortex frame. The Vortex has more flex than it should just because the geometry of the tubes does not increase the stiffness of the frame.
It looks like all the frames you have envisioned are going to suffer the faults of the Vortex frame, which is more flex. The design of the frame should be such that it increases stiffness rather than decreases stiffness. Have the tubes form more of a triangle and you may have to add stiffener tie bars (like the Vortex has) in order to get adequate stiffness from those frames.
I don’t want to stop you from coming up with ideas, but those frames are going to be unneccessarily heavy for trials, muni, or freestyle. If you are going to have the tubing cross as the drawings show, then you may as well cut the weight and make it one straight tube. If you want to make a cruiser, go for it, but I see absolutely no reason to cross the tubes otherwise.
If you don’t notice the difference in mass bebtween solid and hollow rods, maybe you should do a bit more research, both theoretical and practical, before building a frame.
Also, those designs are going to run into two issues: One, if the tubes don’t meet at the cross, they will have to go around eachother, weakening them and making the frame very wide, and they go through eachother then it will be super weak and break. either way that crossing of the tubes is going to weaken the frame and make it bend quite quickly, especially with 1/2" tubing. There’s no way these designs could work using aluminum, based on your current specs. That joint would fail within 5 miles of the first mount, and that’s being generous.
Fabricating these things is also an issue. The average welding shop is not equipped to do long flowing curves in tube. Replicating those curves for two sets of tubes is hard.
Again, I don’t want to stifle your creativity, but there are a mound of practical and theoretical issues with each design you showed, and you should address them before you go to a welding shop. Furthermore, without more precise drawing with actual specs (have you thought about wall thickness for the tubing?), the welder will either say come back with a real drawing or he’ll just laugh. I’m speaking from experience here. I went to a guy and I had similar drawings. It was three months at a drafting board before I made the first cut.
Scratch that. In my ignorance I assumed you were drawing flat bits folding over. I hope you get around to building this frame, at the very least it will look beautiful!
I hope you get around to building this frame, at the very least it will look beautiful!