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Discussion Starter #1
Any reason why this design wouldn't work? It's my first attempt at designing a bike, so any constructive criticism would be appreciated. Thanks!
 

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Chillin the Most
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OMG, how original!!! :rolleyes: While I admire people who are into designing there own stuff, at least try to be original. I'm even if it looks like crap at least you can say it's original, look at zedros bike it's a prime example.

My constructive criticism, try to be more original. Your design looks like a Bullit morphed with a Foes.
 

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Discussion Starter #3
red5 said:
OMG, how original!!! :rolleyes: While I admire people who are into designing there own stuff, at least try to be original. I'm even if it looks like crap at least you can say it's original, look at zedros bike it's a prime example.

My constructive criticism, try to be more original. Your design looks like a Bullit morphed with a Foes.
Yea, I realize that the bike is not the most original one you've ever seen. But it does have a full length seattube to prevent it from looking too much like a mono, and the tubing is slightly different than a bullit. Now that I think Ive got the basics down, ill try something more original next time.
 

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red5 said:
OMG, how original!!! :rolleyes: While I admire people who are into designing there own stuff, at least try to be original. I'm even if it looks like crap at least you can say it's original, look at zedros bike it's a prime example.

My constructive criticism, try to be more original. Your design looks like a Bullit morphed with a Foes.
so there's something wrong with taking two proven suspension designs and trying to combine their aesthetics and function? why does something have to be ugly to be original and good?
i think it looks really good. there's no blatently obvious reason to me why the suspension wouldn't work, and unlike a lot of project bikes, it looks good too. props!
 

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you should be telling us if it'll work, that's what makes it a design.

Right now, you're in the sketch phase, not quite a design yet. You'll see when you start working around the drivetrain, shocks, hardware, geometry, material, manufacturing limitations, etc, that even a single pivot has its challenges when designed from scratch.

When i started designing my bike, it actually had no form until the very end of the design process. I had certain design criteria established first (shock linkages and shock, drivetrain arrangement, floating brake system, geometry, modular concept...), then worked the 'form' of the bike around that, in conjunction with the manufacturing, materials, hardware and structural considerations. So really my initial phase of the design is nothing but a skeleton, linkage iterations, and 'spacial constraint blobs' (ie. assumed minimum structural areas that cant be interfered with), basically a stick figure of a bike. After that i actually went through 3 different forms. Its like the human body, the skeleton defines everything, you can change the apperance later.

The most important thing in design is to follow a concept, a list of objectives, then design around it. Also you'll always have someone comparing whatever you do to something else, just about everythings been done, or people dont understand what nuance is. I've had people ask if my bike was a Balfa, and whether i was looking at Hondas MX suspension at the time. Hell before i even started designing, someone asked me 'what bike i was going to rip-off'....like designing something from scratch could ever be....:rolleyes:

geez, sorry for the diatribe, sure theres more than you asked for lol...
 

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Discussion Starter #6
zedro said:
you should be telling us if it'll work, that's what makes it a design.

Right now, you're in the sketch phase, not quite a design yet. You'll see when you start working around the drivetrain, shocks, hardware, geometry, material, manufacturing limitations, etc, that even a single pivot has its challenges when designed from scratch.

When i started designing my bike, it actually had no form until the very end of the design process. I had certain design criteria established first (shock linkages and shock, drivetrain arrangement, floating brake system, geometry, modular concept...), then worked the 'form' of the bike around that, in conjunction with the manufacturing, materials, hardware and structural considerations. So really my initial phase of the design is nothing but a skeleton, linkage iterations, and 'spacial constraint blobs' (ie. assumed minimum structural areas that cant be interfered with), basically a stick figure of a bike. After that i actually went through 3 different forms. Its like the human body, the skeleton defines everything, you can change the apperance later.

The most important thing in design is to follow a concept, a list of objectives, then design around it. Also you'll always have someone comparing whatever you do to something else, just about everythings been done, or people dont understand what nuance is. I've had people ask if my bike was a Balfa, and whether i was looking at Hondas MX suspension at the time. Hell before i even started designing, someone asked me 'what bike i was going to rip-off'....like designing something from scratch could ever be....:rolleyes:

geez, sorry for the diatribe, sure theres more than you asked for lol...
Wow, thanks for the response. I obviously have no intentions to build the bike, I just wanted to see if I could figure out the leverage on the shock and everything. I need to make sure I chose the correct leverage ratio. Tell me if this is the correct method: I measured the distance from the main pivot to the dropout, and then again from the main pivot to the shock. Will these two numbers give me the leverage ratio? In my case, the numbers were: 21/7.5 which gives me a 2.8 to one leverage ratio. If I use a 2.5X8.5 shock, then that should give me 7 inches of travel, correct?
 

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WheelieMan said:
Tell me if this is the correct method: I measured the distance from the main pivot to the dropout, and then again from the main pivot to the shock. Will these two numbers give me the leverage ratio?
not quite, because the angle of the shock in relation to the swingarm and the swingarm in relation to the frame will alter a simple leverage calculation; the actual geometry is more complicated than that. Its simple to figure out using CAD (if you know how to use it, or know geometry principals) by drawing before and after iterations of the swingarm travel, and finding the mutual point where the shock iterations meet at the appropriate shock lengths. This will give you an infinit number of defined shock postions, where then you have to decide on the shocks initial and final angle to the swingarm 'triangle', then decide on the final shock postion. This is easy to set up if you know how to set up constraints, then its just a matter of making the appropriate design choices. This is why you start with a simple skeleton and not a bike form, so you can easily manipulate the system. Theres alot more to it than drawing an outline and relying on deceivingly simple (and wrong) equations. You have to map out what the system is actually doing.
 

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that pivot point above the shock.. if its not perfect it will be extended to far and fold over itself and be bad new's... am i wrong
 

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eci
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Create a floating brake system like the gemini DH bike. Also id move the shock back in the swingarm to get more travel out of the bike.

There's nothing wrong with using prior designs. if you make it better than kudos to you
 

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Shortcutting Hikabiker
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Check out my design: Reverse Horst Link, Pull Shock, 11 inch travel, 14 inch travel moto style fork, 13.5 inch brake rotors. Yeah I rock.
 

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Acme54321 said:
Check out my design: Reverse Horst Link, Pull Shock, 11 inch travel, 14 inch travel moto style fork, 13.5 inch brake rotors. Yeah I rock.
looks like an oldschool M-1 with the rear triangle on upside-down......
 

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Discussion Starter #14
zedro said:
not quite, because the angle of the shock in relation to the swingarm and the swingarm in relation to the frame will alter a simple leverage calculation; the actual geometry is more complicated than that. Its simple to figure out using CAD (if you know how to use it, or know geometry principals) by drawing before and after iterations of the swingarm travel, and finding the mutual point where the shock iterations meet at the appropriate shock lengths. This will give you an infinit number of defined shock postions, where then you have to decide on the shocks initial and final angle to the swingarm 'triangle', then decide on the final shock postion. This is easy to set up if you know how to set up constraints, then its just a matter of making the appropriate design choices. This is why you start with a simple skeleton and not a bike form, so you can easily manipulate the system. Theres alot more to it than drawing an outline and relying on deceivingly simple (and wrong) equations. You have to map out what the system is actually doing.
Ok, I'm following ya, I guess the frame gets nearly 8 inches of travel, and not the 7 that I had planned. Concerning the floating brake, do they clamp around the seattube like a front derailleur, or can you specifically design them to attach to the frame?
 

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WheelieMan said:
Concerning the floating brake, do they clamp around the seattube like a front derailleur, or can you specifically design them to attach to the frame?
you can design them however you want...if you dont know how they work, or why they work, and how a particular 4 bar geometry affects the system, simply dont design one in.
 

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Discussion Starter #16
zedro said:
you can design them however you want...if you dont know how they work, or why they work, and how a particular 4 bar geometry affects the system, simply dont design one in.
Ok, I understand how they work, but I just don't know how to adapt one to my frame. Is there a certain distance the caliper must rotate in order for it to be effective?
 

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Looks pretty good from a non-engineer's perspective. Don't listen to people that don't have anything good to say, those people will never even try to make their own bike. In their small minds it makes them feel better to bag on people who have the nuts to put something out there and open themselves to criticism.

But, aah, you probably should listen to Zedro. :D
 

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WheelieMan said:
Ok, I understand how they work, but I just don't know how to adapt one to my frame. Is there a certain distance the caliper must rotate in order for it to be effective?
thats the part about understanding how they work. The geometry of the linkage affects the rotation and to some degree imparts reaction forces with the chassis throughout the travel, which in turn affects performance. Different designers have different methodologies and theories to how they design them, and some just randomly slap a linkage in there.
 

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eci
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mount the brake bracket horizonally lower than the rear axle. (you have to have a thru axle to make this work right) Then design it so the floating brakes moves throughout the travel of the bike. Have the floating piece attached past the rear axle so as it move you still have room for the brake to move. Or you could place the bracket just below the swingarm and then you have less length of travel in the brake assembly. personally i like having the brake lower. it looks more badass
 
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