[TrumbullHucker]

now before everyone goes absolutely nuts and starts flamming, i have always had this suspension design in my head, and finally iv drawn it out on autocad and i am extremely pleased with how it ended up.
leverage ratios, axle path, how much travel, and all, are still undetermined; i dont even know how to set up leverage ratios (especially with this design The only thing known is a 65degree HA
yeah the suspension design could seem pretty extreme, to much stuff going on etc etc. i guess you can say its like an f5 and a vp free and a commencal and a brodie 8 ball had a kid...
in the future, if i plan on pursuing this goal and actually welding the frame, my first "proto" will be tig welded out of stainless steel( attached pic of stainless weld) so i can focus more on the actual performance of the bike other than the weight. 2nd proto would most likely be out of aluminum once i know how to tig aluminum good.
The bottom bracket area and bottom seat tube area and bottom link and the "linkage push rod" would be milled out of solid steel or alluminum ( YES i know it will be heavy!!)

Im not even totally sure if this design will work, considering the 2 links on the swingarm like a vp kind of deal.

frame builder's please give me some tips and advice or changes to this because...knowledge is power!!!!!!:biggrin:


release it to the wild!!

 

[HAB]

You're themarsvolta on mtbr, right? I recognize the weld shot.


I'm in no condition to offer you any useful advice, so I won't try. Good luck though.

 

[zahgurim]

From a first glance, it looks like you have 5 pivot points, and that it would fold up on you.

Ditch the lower "virtual pivot link" and make that a solid swingarm coming from the frame, and it won't fold on you. As to the leverage ratios, I'll leave that for a designer more experieced than I.

 

[HenryTheHammer]

Yup, too many pivots. The dw'ish link on the bottom wont work in the current configuation. If your goal is a virtual pivot, make the dogbone and the cam link one integral piece.

Oh, and as usual. Looks flexy and will it be available in Rootbeer?

 

[TrumbullHucker]

haha yea tmv55 is me

ahh oh well, it will be alittle easier to make without that vp link.

yea flex is an issue that i was thinking about, specially w that swingarm. but ill design some more for some additional strength. and the first one will be out of stainless steel so it would be alot stiffer then al

 

[binary visions]

leverage ratios, axle path, how much travel, and all, are still undetermined; i dont even know how to set up leverage ratios (especially with this design The only thing known is a 65degree HA

With respect... you're starting at the wrong end. There is nothing interesting or magical about laying out links in some kind of bizarre or unique pattern if you have no leverage ratio, axle path or travel length to achieve.

This isn't a design, it's just a picture. You don't start with a picture and end up with a design. You start with a set of goals, work through a design and end up with a picture. Certainly there are aesthetic choices you can make along the way, but those are to be made within the confines of your design and goals, not the other way around.

 

[IH8Rice]

With respect... you're starting at the wrong end. There is nothing interesting or magical about laying out links in some kind of bizarre or unique pattern if you have no leverage ratio, axle path or travel length to achieve.

This isn't a design, it's just a picture. You don't start with a picture and end up with a design. You start with a set of goals, work through a design and end up with a picture. Certainly there are aesthetic choices you can make along the way, but those are to be made within the confines of your design and goals, not the other way around.

you are wise my friend.


but nice weld job buddy..looks like a line of dimes

 

[LMC]

With respect... you're starting at the wrong end. There is nothing interesting or magical about laying out links in some kind of bizarre or unique pattern if you have no leverage ratio, axle path or travel length to achieve.

This isn't a design, it's just a picture. You don't start with a picture and end up with a design. You start with a set of goals, work through a design and end up with a picture. Certainly there are aesthetic choices you can make along the way, but those are to be made within the confines of your design and goals, not the other way around.

indeed, tell us what you want to achieve with the frame and you will no doubt get a multitude of helpful replies.

linkage is a good program to buy to work out the leverage ratios. find it at www.bikechecker.com

 

[TrumbullHucker]

binary visions
i understand that i kinda started at the wrong end, i should of started w some thoughts of ratios and stuff like that, but i just don't know how to calculate stuff like that. i would of approached ridemonkey with alot more data, but im not to knowledgeable in that area yet.

just curious, how would it "fold" on itself??

the point of this post was just to show the most basic picture of a frame design that has been floating in my mind for quite some time

 

[binary visions]

The point is that you are artificially constraining yourself if you do something like draw a picture of what you want a complicated linkage to look like without an idea of how it will function. It's not a frame design - it's a frame picture.

Why are you making the linkage? What do you hope to achieve? Why not a single pivot, which will be lighter and easier to build? What purpose does this complicated system serve? Since you have no leverage ratios or axle paths or travel, the answer is "no purpose whatsoever."

So. You are seeking more information about something that you've created that has no purpose. What if I drew a picture of an engine with S-shaped cylinders and said, "hey guys, can you help me figure out the horsepower here?"

I'm not trying to be harsh, just show you that there is no place to go from here. You can't present a picture and expect everyone else to provide the basics. You have to start with the basics - desired leverage ratios, axle paths, design considerations like strength, stiffness and complexity - and go from there. You don't do nuclear physics by drawing a reactor in crayon. You do it by learning and knowing basic physics first.

 

[sirknumskullgt]

You guys are being too harsh on him. A new linkage design has to be thought of at both ends not at one end or the other. A bike can have a million different looking linkage setups with the same leverage ratio. You have to think of what you want it to look like as well if you want a unique design. Otherwise whats the point in designing your own bike when there are many fine designs out there already.

You can still use the one youve got here by adding another vp link offset from the one that is there, connecting it to the shock linkage point on the rear swingarm or somewhere between it and the chainstay pivot to control the motion of the rear end. This will also help with the stiffness issue. Also it gives it a nice rearward wheelpath, so you will need to put an idler pulley in to correct the chain line. I drew up a little sketch in Solidworks to see that it actuates correctly and it does. With the two vp links you will be able to tailor the suspension in many ways to exactly the specs you like including wheelpath, leverage ratios and all that important junk.

BTW I have been designing and building my own full suspension bikes for the last 3 years and have 3 fully functioning prototypes under my belt so I do know what Im talking about. If any of you nay sayers have any experience that would lead to you object please present it. My designs are up on my website http://www.nobsbikes.com

Trumbull Hucker, if you have any other questions about what i mean with the design changes just ask. And your welds made me a believer by the way. Stuff dreams are made of bro. Keep it up.

 

[TrumbullHucker]

thanks sirk

i am aware that nothing is calculated yet, only an "image" or whatever...


then i guess it will be worth it to purchase bike checker then to figure out the calculations of axle path, leverage ratio, pedal kickback etc etc

how did you figure out that it works on solidworks? im very interested in seeing what your seeing.

and i do enjoy your bikes, sissorlink bike looks very sweet

 

[sirknumskullgt]

[url=http://www.ridemonkey.com/mountain-bike-photos/showphoto.php/photo/5753][/URL]

This is an edit to the picture of your design with the extra VP link making sort of a 4 bar thing.

[url=http://www.ridemonkey.com/mountain-bike-photos/showphoto.php/photo/5754][/URL]

This is A Screenshot from Linkage of the frame I drew up for you. Shown is the Leverage ratio and you can see the axle path. I gave it 170mm of travel front and rear with a 2.5 inch stroke shock. I wasnt sure what you were looking for in a bike so I chose something freeride oriented. Im trying to get you away from the whole "no hucking" thing. hehe

It looks pretty good to me. Buy linkage and you can make your own drawings like this. The leverage ratio is pretty awesome for one. Drops from 4.1:1 to .5:1 on this particular one.

 

[sirknumskullgt]

Hey I hope you come back to check this out I burned a few hours making your dreams come true here.

 

[TrumbullHucker]

sorry bud i was real busy with some college projects

im really surprised that the linkage can actually work!

i just dont understand why there needs to be a secondary link above the original vp link

thanks for doin the linkage program, im def going to be purchasing that program now, knowing that it can create something like that!

 

[sirknumskullgt]

Any linkage can work well if you make it right. Even the slightest deviation in proportions and it will be all funky however.

Without the additional link to control the motion of the rear end the frame would as they have been saying "fold up." This is because it is able to move in a direction that will not compress the shock which is what it would rather do then endure the force of the spring. Just because it resembles a bike on a 2D sketch doesnt mean in real life it will act like one. Suspension isnt magic as im sure you are aware of. Its a simple problem of forces and leverage arms and if there is an ability for it to take the path of least resistance as it would in this case then it will. Its hard to visualize if you havent seen it before for yourself in a virtual model or something made of cardboard and tacks on a table. I would try the latter method if you do not have access to a solid modeling program. Just make something about the right proportions and try to move the suspension from the rear axle like it would under compression. You will quickly see how it wont act like you would hope.

The extra VP link will allow it to function well and add alot of stiffness to the rear end in general. The only other way I could think to do it is something along the lines of the Sinister Passion. This is a VP prototype that could be considered underconstrained but it is made up for by having an elastomer in the mix to stop the swingarm from moving too far out of whack. Just search around for it and you will see what I mean.

 

[TrumbullHucker]

ahh i see why, cool!

yeah my friend suggested me using an erector set to set up the suspension to see the pivot action and such

can't wait for the part of the semester that we do t.i.g welding!:biggrin: