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rofl I haven't published any dimensions or measurements and somehow you got it nailed from a screenshot you took from facebook and drew lines on in microsoft paint
Yep. It truly is that simple to show the way the geometry will work. Though it's easier with Solidworks than Paint.
 

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but it proves a regressive and overly soft rear suspension. why do you have such a hard time admitting you put no thought into the rear suspension other than where a shock would fit and your "works fine" just means it's bouncy. what really pisses me off is you have the nerve to build this bike and try to sell it to someone, the sheer arrogance of never questioning your own design is enough if you're the only one riding it, but the idea that you're going to pass this off to someone else in the hopes of making money from it is just appaling. actual engineers go to jail for that kind of negligence.
 

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We're just here to help you build something safe
 

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Discussion Starter · #25 ·
We're just here to help you build something safe
hah some people are but that dude up there started square one with accusing me of trying to murder someone. He saw a picture of an incomplete bike and then spent the entire day angry and insulting me and swearing at me. He even made an angry little video about it. The only thing he’s really done is demonstrate his need of therapy.
 

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You might be able to get in the ballpark, but drawing lines over a screenshot is not going to get you down to the mm.
Getting into the ballpark is more analysis than you've ever done on it though, am I right?

You don't need to get down to the mm to show what happens. There is nothing wrong with the analysis that was done. It's a legit way to see what's happening when the bike goes down the road. I have no idea what kind of exchange you two had about it, but the fact is your suspension geometry is flawed if you care about how things work. A falling rate rear suspension isn't the end of the world but it's also not something anyone would attempt to end up with on purpose.

Some people care about HOW things work. Others are satisified that they work at all. People that care about how things work will never buy into the thought that your rear suspension works well because their definition of working well goes beyond the seat not dragging on the tire.

What you've ended up with is a suspension that will be stiff when you're bopping down the road and soften up when it should be working to keep from bottoming out. You'll need to use a stiffer spring to keep it from bottoming easier which will also make the ride stiffer for the smaller bumps. Doesn't it make more sense that you'd want something that is softer on the small bumps and then stiffens up to keep it from bottoming on large bumps? Well it only makes sense if you are more concerned with how it works than how it looks, or how easy it is to make.

Tell people you're fine with having a falling rate suspension, it will work well enough for what you're trying to do. Denying the results of what's been shown because no one has precise measurements is a cop out. Precise measurements aren't needed to demonstrate what happens when the pivot points of the system are laid out in that configuration.

If you want to get the bike lower, replace the rear shock with a (shorter) solid strut and call it a day. No more falling rate suspension, no worrying about bottoming out because it's always bottomed out. I'm not kidding.

FWIW one of my current projects uses an Ohlins rear shock, another is a hardtail. Different horses for different courses. Accept the consequences of choices made instead of arguing the consequences aren't real.
 

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Discussion Starter · #27 · (Edited)
Getting into the ballpark is more analysis than you've ever done on it though, am I right?

You don't need to get down to the mm to show what happens. There is nothing wrong with the analysis that was done. It's a legit way to see what's happening when the bike goes down the road. I have no idea what kind of exchange you two had about it, but the fact is your suspension geometry is flawed if you care about how things work. A falling rate rear suspension isn't the end of the world but it's also not something anyone would attempt to end up with on purpose.

Some people care about HOW things work. Others are satisified that they work at all. People that care about how things work will never buy into the thought that your rear suspension works well because their definition of working well goes beyond the seat not dragging on the tire.

What you've ended up with is a suspension that will be stiff when you're bopping down the road and soften up when it should be working to keep from bottoming out. You'll need to use a stiffer spring to keep it from bottoming easier which will also make the ride stiffer for the smaller bumps. Doesn't it make more sense that you'd want something that is softer on the small bumps and then stiffens up to keep it from bottoming on large bumps? Well it only makes sense if you are more concerned with how it works than how it looks, or how easy it is to make.

Tell people you're fine with having a falling rate suspension, it will work well enough for what you're trying to do. Denying the results of what's been shown because no one has precise measurements is a cop out. Precise measurements aren't needed to demonstrate what happens when the pivot points of the system are laid out in that configuration.

If you want to get the bike lower, replace the rear shock with a (shorter) solid strut and call it a day. No more falling rate suspension, no worrying about bottoming out because it's always bottomed out. I'm not kidding.

FWIW one of my current projects uses an Ohlins rear shock, another is a hardtail. Different horses for different courses. Accept the consequences of choices made instead of arguing the consequences aren't real.
redacted because to hell with it. You had the choice of conversation and discussion and instead chose insult and condescension just like your buddy. So...it’ll work whether you want it to or not. Surprisingly i do jot need either of your approval. Hope you have a good day, though.
 

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lol If you put the right progressive rate spring on there you might be able to cancel out some of the regressive spring tendency, but that's not going to address the dampening weirdness if that happens. I'd be happy just to see the frame not flex as if it has a rubber hinge in the middle and no cracks form around your welds.

... you can do non-destructive x-ray testing of welds btw. They do that with aircraft parts. Fractures will show.
 

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Discussion Starter · #32 · (Edited)
lol If you put the right progressive rate spring on there you might be able to cancel out some of the regressive spring tendency, but that's not going to address the dampening weirdness if that happens. I'd be happy just to see the frame not flex as if it has a rubber hinge in the middle and no cracks form around your welds.

... you can do non-destructive x-ray testing of welds btw. They do that with aircraft parts. Fractures will show.
I don't think a progressive spring will be required...it really wouldn't compensate quite the right way anyhow. I doubt it's going to be an issue, even though it did have a falling rate it's not as dramatic as some people might have you think. Once an appropriate spring rate is sorted out it's most likely not going to be noticeable to any considerable degree.

A lot of the load bearing components will be welded by someone with a lot better equipment and skill than I do so I'm not very concerned about the welds themselves, the general strength of that t-bar area of the frame is where my head is at. I'm likely going to find a way to brace that mount to where it'll spread the load around to somewhere else. That whole part of the bike is a month away...assuming I have my wheel rigged out...
 

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putting a heavier spring on it is just going to mean more force going into your frame where you have the shock mounted, why not ask for suggestions on how to mount the spring so that you get close to the wheel rate you need without making compromises that cause problems elsewhere?
 

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for example: post your picture and say "this is the shock I'm using, here's the bike and rider weight, I want X mm of rear travel, with a suspension feel somewhere in the ballpark of a sportbike", then people with knowledge about suspensions would tell you how to position that particular shock to the swingarm and frame to give you something in the ballpark, when you come here looking for pats on the back and absolutely against the idea of changing your design, you're not going to get what you're looking for.
 

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Like when you order a set of racetech springs or hagon shocks, they get a whole bunch of info about the riders weight, bike, etc so they can get it right
 

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Discussion Starter · #36 ·
you're not going to get what you're looking for.
You're really driving that point home by continuing to try and angrily force feed your advice to someone who neither requested nor needs it. Next time I post a picture of the bike I'm going to do it without tires so I can enjoy your commentary about how unsafe it is to ride without tires. I really hope you find a way to manage your temper dude, no one needs to get that wound up over someone else's projects. Go for a ride or something...anything else...because your effort and stress and temper are wasted here.
 

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You're really driving that point home by continuing to try and angrily force feed your advice to someone who neither requested nor needs it.
That’s because he’s right, and you’re not. Call us angry old men al you like. You ain’t hurting anyone’s feelings here. Quite honestly, no one here gives a fleeting flying fig what yours (or anyone else’s) bike looks like. What we care about is how it WORKS. You made the statement that if you had placed the mount higher up no one would’ve batted an eye. You are correct because that’s where it should be. Raise the front mounting point up above the rear mounting point so you get a more progressive shock compression. Even then you will be somewhat limited by the fact that the shock was designed to utilize a rising rate linkage and only has about 2 inches of total travel. But at least the rear won’t be getting all wobbly and pogo-y on whoever tries to ride it.

The new admins make us play nice now. But had you been here even a year ago, you’d know angry old men. There are some old forum traditions that aren’t so frowned upon, though....,
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