fun with auto cad
- Thread starter rowlands
- Start date
giant glory
Not quite champ.
...wouldnt the upper link hinder the movement of the rear triangle on that design?
It's made out of stretchy alum.
The way it's shown it certainly looks like it would. It is possible to have a design like that, but shock i2i/stroke would have to be specific to the frame and couldn't change. The coupler curve of the top link would only work for a specific shock i2i/stroke, any other shock of a different size, and the top swing link would be preventing the suspension from cycling through the travel.*
Kinda weird, but I like it.
*Pretty sure that's the deal, it's been a long day so I could be making stuff up. Is that what you had in mind greenblinker? (I know you're an engineering student as well IIRC)
You might want to think about a couple of things.
The longer the links, the more flex/slop the rear will have especially in a 'vertial' orientation. The other thing is, at the orientation of the links, it is quite close to allowing the top link to flip backward...and that would not be good.
The longer the links, the more flex/slop the rear will have especially in a 'vertial' orientation. The other thing is, at the orientation of the links, it is quite close to allowing the top link to flip backward...and that would not be good.
Yes it would, BIG TIME. Probably get a couple inch of travel before it rips the pivot off.
Nice drawing, but as said the rear travel path is very odd. I cant really see that working well when you ride it.
If you are designing suspensions your best to do a series of models with the suspension more compressed on each one. Then over lap then and draw a travel line. You can also tell then if anything will get in the way as well as actual travel path.
If you can get a copy of ProE it is a lot more useful for bike design.
If you are designing suspensions your best to do a series of models with the suspension more compressed on each one. Then over lap then and draw a travel line. You can also tell then if anything will get in the way as well as actual travel path.
If you can get a copy of ProE it is a lot more useful for bike design.
it probably needs alot of refining to get the design dialed but this is just the first draft, I wish I could get that linkage program to work on my computer to get the suspension and axle paths dialed but unfortunatly the program dosen't seem to work with mac's.
Use Solid Works. And before you give me the Autocad argument, I've used Autocad 22 years. SolidWorks WAY better.
The reason I mention this is because With SolidWorks, you could work out your upper linkage issues.
Good luck with your project!
The reason I mention this is because With SolidWorks, you could work out your upper linkage issues.
Good luck with your project!
I wish I could My school dosen't have solidworks and I don't really want to dish out all of the $ on the program and I haven't been able to find one compatible with mac.Use Solid Works. And before you give me the Autocad argument, I've used Autocad 22 years. SolidWorks WAY better.
The reason I mention this is because With SolidWorks, you could work out your upper linkage issues.
Good luck with your project!
find it off a torrent site like isohunt or something
It used to be $4,000-5,000. Not sure what they charge for it now.stupid question but.... how much was that software? im trying to find a free one cause i have a good idea...but i havnt had any luck
can we get some details form the designer regarding what the expected benefits of the of this design are over currently marketed options? he said the design had been in his head for a while. why is this special or desireable?
go to engineering school, there's so many things wrong with it
Use Solid Works. And before you give me the Autocad argument, I've used Autocad 22 years. SolidWorks WAY better.
The reason I mention this is because With SolidWorks, you could work out your upper linkage issues.
Good luck with your project!
It's a little sad that it took you 22 years to figure it out....
Sell it to Da Bomb Bikes, They'll take a design like that.
The only reason I actually drew it is because it is something a little different, and I have never seen it before so I knew I wasent just copying another design.
Im going to try and get that linkage program and dial the suspension, but for now I have no clew on how much the chainstays grow or if the suspension will even work, as I said before this is the preliminary drawing so nothing is dialed. I just wanted to get it on paper and get the geometry right.
If anyone wants to dial in the suspension using linkage or sugest changes feel free and I will make a second draft with all of the changes.
A quick first glance and any technically-inclined dudes/dudettes will tell you that your linkage will not work, period.
You can manual plot using autocad the axlepath/swingarm movement (or the lack of it) if you know how to do it.
Yeah, I've been doing that on the bike I've been working on. It takes 2 minutes to plot out a decent wheelpath.
There are a few things wrong with your bike design.
First off your wheelbase setting is wrong since you are forgetting that there is axle offset from 42-47mm on most 200mm forks.
You also will have to have a pulley system for the bike to work properly. There would be a massive amount of pedal feedback without it that just would not work.
Your leverage rates are off. Your bike does not have a 3 to 1 leverage. It is more like a 5 to 1.
Ditch your autocad program and spend $25 to get Linkage. Go to www.bikechecker.com to pick it up. This is the best program for quickly and easily coming up with suspension concepts as well as analyzing your design. I put your bike into the program in about 5 minutes.
Hope this helps,
Evan
First off your wheelbase setting is wrong since you are forgetting that there is axle offset from 42-47mm on most 200mm forks.
You also will have to have a pulley system for the bike to work properly. There would be a massive amount of pedal feedback without it that just would not work.
Your leverage rates are off. Your bike does not have a 3 to 1 leverage. It is more like a 5 to 1.
Ditch your autocad program and spend $25 to get Linkage. Go to www.bikechecker.com to pick it up. This is the best program for quickly and easily coming up with suspension concepts as well as analyzing your design. I put your bike into the program in about 5 minutes.
Hope this helps,
Evan
How many bikes have a constant leverage ratio?
Can you post it here? I'm curious to see what you've got in terms of wheel path.
According to Linkage, leverage ratio is 1:5,7 to 1:5,5 on this design.
Personally I think it's a great start! Drawing stuff out in CAD is a great way to get your mind working around frame design. I know the first frame I drew (in high school), took me forever to do and a frame designer/builder would have looked at it and scoffed(and it was just an hardtail), but either way I learned a ton from that process. Keep up the good work man!
Oh, and for those looking for a free 3D parametric modeling program, check out Alibre. You can download a trial off their website. It's limited from the full version, but still a place to start.
Oh, and for those looking for a free 3D parametric modeling program, check out Alibre. You can download a trial off their website. It's limited from the full version, but still a place to start.
There is also a stand alone program called Linkage, where you can play around with linkage designs. I dont know how "high level" it is, but if you need it i can send it over via email. I have version 2.0 and its from 2002 or something. send me a pm if you need it.
^ That programs been discussed a few times in this thread already. Albeit a good program, it shouldnt be completely trusted when used inversely (taking a design from a .jpeg and "plotting" it) but it puts out good numbers and graphs if you actually design the bike in a cadd like program and plot it in linkage.
BTW upgrade to version 2.5, 2.0 doesnt give as much info or freedom in design.
Another good free 3D drafting program is Rhyno. not sure if its still free but it was a pretty good program from what i remember. If you have access to a university with solidworks by all means use it tho, and take a few lessons if you have to. Its pretty easy and fun to use.
BTW upgrade to version 2.5, 2.0 doesnt give as much info or freedom in design.
Another good free 3D drafting program is Rhyno. not sure if its still free but it was a pretty good program from what i remember. If you have access to a university with solidworks by all means use it tho, and take a few lessons if you have to. Its pretty easy and fun to use.
You don't need the Linkage program to figure out leverage ratios, etc... It's all simple math that you can just do by hand, and you'll get a better feel of how changing variables effects things because you'll see the numbers in their respective equations. If you really want to LEARN, don't use the computer program. If you just want to be a CAD jocky, then use the program.
At the level these guys are involved im not sure they are very interested in learning the math needed to graph the leverage ratio curves. obtaining a simple travel/stroke ratio is simple however and most people should know that i'll agree. Some of it's not as simple to the general public esp when you get into moments, ic, etc. lol. I do agree however that learning the math is neccesary if you wanna push it to the next level in any form of engineering, in fact its required as I'm finding. and as far as being a CAD jocky, well i can see that being a bad thing if you consider linkage cad, but 3D cad has its place and the users are certainly not jockys, more like chariot racers or something
Care to explain how this is done? I knew the design would probably not work but this is just my first go.
Anybody have any recomendations that would make this design usable? I really would like to make this work and at some point I wouldn't mind building it but theres no point in that if it dosent work.
Thanks for all of the help so far
Shorten ur lower link so it more closely resembles a VPP design. In doing that you'll hafta adjust the shock attachment point on the lower link and then adjust the shock angle and frame attachment point to compensate for the leverage ratio change. and if you haven't DL'd linkage 2.5 demo version do it and play till ur hearts content with crazy designs and try and lock up the program with ones that physically won't work.