Trials Frame Design Help

I agree. I think you should either seal the tops of the tubes or cut the flush with the black piece. It might take a little bit away from the style but then you don’t have to worry much about a bad injury or getting stuff stuck in the tube. Those tubes sticking up would make it really nice when you put your foot on the frame.

EDIT: Also, if you are serious about selling it someday, then you might want to make it good for street too, because the market might be a little small if it was only good for trials.

OK i made tube caps and for jokes i made it in carbon and ti

i dont ride street. so that makes a good street frame?

ohh you used my idea, thank you if you did :wink: I’d love to this on a coker, 29er or those novelty unicycles one day. That way people don’t have to cut the seatpost to reach the pedals. :smiley: :smiley:

Yeah, this design will be. If it was for pure trials then you would probably want to make where you would normaly put your foot more angled, this way it doesn’t get in the way of your knees and would prevent some painful falls. because those tubes come to the top, it should be perfect for street.

I liked the look of the different colors with the green tubes an black tube connector. Of course this doesn’t have anything to do with the mechanical design.

Also, are you actually going to have this manufactured? I really like the look of it and I might consider buying one if you do produce them!

If you are going for a light frame, ditch the ovalized tubing and go with square, it puts more metal in the two axes its needed most, then you can use thinner wall tubing compared to round or ovalized. That crown setup is going to be heavy and not as stiff as it could be if you used some gussets out of tubing or sheet/strip stock running from leg to crown.

Having suspention above the axle would have the same effect as a suspention seatpost. The idea of a fully suspention uni has been discussed at length here.

But circular and ovalized legs will resist tortional forces better. I think eliptical legs, like the ones he has pictured is ideal. Wheather more oval, round, elliptical, square, or rectangular probably needs more testing. My money is on elliptical.

Yeah but the legs dont get twisted nearly as much as there is a side load on the frame sideways, which is where square tubing comes into play.

no i mean have a t-bar suspension that goes from left to right and in the middle and meets halfway. Something like this. It’s a odd-drawing but it explains what i mean.:smiley: :smiley: :smiley:


When jumping you rarely land streight side to side or forward to back, and almost always at some angle, so rounded sides will take more force for the given amount of metal. This has been increased in the last few years in motorcycle disighn.

ie: When Honda came out the new CBR 954 (I think in 2003) They found the tortional stiffness of the swingarm increased by 25% if they rounded the corners of it’s box tubing.

Look at Ducati’s diminance in World Superbike since its inception about 20 years ago. They only use round tubing in their frames.

So where is the wheel, what is it directly connected to?

I would certainly disagree with your statment about landing straight on sideways. Watch trials videos, many people land gaps straight sideways. I think round would be best for the crown because there is a twisting force on that, but def stick to square on the legs.

But perfectly?

Almost every landing I’ve seen had some angle to it. Even the ones where they landed “streight”, the angle was like 5-15 degrees. Thats all it takes over time.

It would be great if it could be tested by a machine to find out what design works best, but I don’t see how it could generate the stresses in the same way a rider does and all the different riding styles. The best I think we can hope for is a machine that would very specific forces in a several specific directions to a series of designs, and all taken on a test run w/ the same rider testing all designs. Then retest them to find how stressed/worn those areas are. Find the design that elliminates all the week spots, and produce that frame. All that may be too expensive for our small sport though, and just go w/ trial and error.

Not really, its not needed. Kh framees are about as light as anyone is going to need/want.

ive got inventor pro 11 at home, its great !

True, it would be hard to get the frames much lighter. I think a substantial amount of weight could be saved in the hub and other areas, but that would be VERY expensive to produce these in low quantities, frames are easier.

Edit: Isn’t the KH 20 frame something like 1.2 lbs?

Oh i didn’t add the wheel because obviously it would be connected to the wheel. My bad. :smiley: :smiley: :smiley: :smiley:

the only problem i see with that frame is the fact there is no originality to it.

I mean it looks pretty much like a nimbus II/devil crmo or qu-ax trials frame.

How are you gonna join the two metals/carbon and Ti together?

Also why not make it go in at the top so the frame is abit wider at the bottom so you dont hit your ankles.

also i think a long neck trials frame would be awesome, why not make yours a long neck frame?

Once you have a good 3D model and have a rough idea about the forces you could put it in a FEA program. The forces don’t have to be accurate but the direction does. If you put say 5 times the force on the frame but in the correct dirrection it will give you a pretty colourfull picture showing the high stress/weak points (weak points are weak points, no matter what the magnitude of the force is).

This is how i designed my BC plates. I put holes in all the low stress areas to cut down on weight. They will yeild (bend and not bend back) once you have ~80kg of downward force on one plate. I also used the FEA program to see how much the plates would flex downward and angled them up (like evan’s plates) to compensate.


wow i so didnt know you coul do that. Thats awesome :smiley:

i’m gonna have to do this for a few of my projects. and for a bc plate that is like idea i guess like you said.

What was it made out of before you joked it into carbon and Ti? In other words, there isn’t much one can comment on the design unless we know what it’s to be made out of, and how those parts are to be attached to each other.