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What ever you do, make the frame so you can use either the sandwich or the rockerbox mount method.

Meanwhile, ten frames later, back at the ranch. :)

You should look at MacIntosh frame designs. They are simple, and they work.

Mc 1.jpg

Mc 2.jpg

Danger, is my business."

P.S. : N.B. not the same bike in the images.
 

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I just don't see the need to use the valve cover at all.

Make a bracket that can attach to the 4? head bolts you can get to with the cover on.
Or create a stiff frame that doesn't need contact at the head.
 

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Discussion Starter #84
IMG_0996[1].JPG

where it stands so far, still have to tie in the head mounts, front case mounts, and design the rear shock linkage. wanted to go with direct mount between the carbs and swingarm (swingarm would be upside down), but that wouldn't allow for progressive rate, and spring is straight rate and damped, so will likely build a linkage design to mount shock under engine and give a progressive rate to the rear end
 

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View attachment 13288

where it stands so far, still have to tie in the head mounts, front case mounts, and design the rear shock linkage. wanted to go with direct mount between the carbs and swingarm (swingarm would be upside down), but that wouldn't allow for progressive rate, and spring is straight rate and damped, so will likely build a linkage design to mount shock under engine and give a progressive rate to the rear end
You don't need progressive suspension rates or a linkage system on this bike. Egli, KTM ( I think ), Harris and ATK did'nt need it.

Danger, is my business."
 

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It is nice to know that some manufacturers are able to build single shock bikes without linkage systems, so you should, too.
These same manufacturers have models with a single shock and a linkage system, so you should, too.

Wow, I guess that advice is useless. I wonder if there is a scientific basis for choosing one over the other? (of course there is, it was a rhetorical question to point out the absurdity of the original advice)

I like the frame and once you get it to the point you can start fitting the shock and mounting points you should be able to make it work to fit your needs and constraints.


Ken
 

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Linkless systems mean less weight, and less bearings to wear out or components to fail. Good enough for some Buells. And plenty of other Marques.

I guess straight rate systems were good enough for Norton's IOM TT rotary, and Moriwaki's superbikes and 500cc GP bikes. But what would they know?

I could name drop a GP chassis guys name, but I won't. I asked him how important progressive rate suspension linkages / rates were on road race bikes. He said it is basically BS, and he actually preferred straight rate setups for both road and race track use.

Funny how I held exactly the same views for years, and his opinion concurred with mine.

Danger, is my business."
 

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Discussion Starter #89
It is nice to know that some manufacturers are able to build single shock bikes without linkage systems, so you should, too.
These same manufacturers have models with a single shock and a linkage system, so you should, too.

Wow, I guess that advice is useless. I wonder if there is a scientific basis for choosing one over the other? (of course there is, it was a rhetorical question to point out the absurdity of the original advice)

I like the frame and once you get it to the point you can start fitting the shock and mounting points you should be able to make it work to fit your needs and constraints.


Ken
I emailed Tony about his thoughts regarding progressive rate, his book doesn't really seem to detail circumstances where it's highly beneficial, actually says that in some cases regressive is advantageous, but doesn't go on to detail those, haven't heard back. I can imagine that for an overall feel, it might be nice, so that the more travel is available, the more can be used, and when it's close to being used up, you're not running against the stops, but that's just me, I've never ridden a progressive link rear suspension, so I'd be interested to see what people are running on the track and why
 

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I emailed Tony about his thoughts regarding progressive rate, his book doesn't really seem to detail circumstances where it's highly beneficial, actually says that in some cases regressive is advantageous, but doesn't go on to detail those, haven't heard back. I can imagine that for an overall feel, it might be nice, so that the more travel is available, the more can be used, and when it's close to being used up, you're not running against the stops, but that's just me, I've never ridden a progressive link rear suspension, so I'd be interested to see what people are running on the track and why
My God, don't ask TF anything. The last time a bike he built won a race it it must have been 1971.

Danger, is my business."
 

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BTW - forgot to ask how did you go welding up the rocker cover? Looks like you got it sorted but did it give you much grief?
 

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I guess we should make all our suspension decisions based on some street bikes and racing technology from 20 years ago. While it may be interesting what some mythical GP chassis guy knew about flexiflyer framed racebikes and give up trying to do anything better. However, I am a google image expert so I asked the Google about MotoGP rear suspensions and all the pictures of those bikes had fancy shocks with linkages and stuff. I wonder why. I will be curious what Tony Foale has to say about it since he is an expert and actually makes stuff. I bet he even has friends in the industry that aren't imaginary that know stuff, too. Did I mention that I raced against Tony at Mid-Ohio and then I visited with him in the pits while we looked at his frame that he built. Tony Foale exists, is a real person that impresses rather than amuses me.

Ken
 

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Careful now Ken - you're in danger of going against your own mantra here and engaging the dancing monkey.

Using a swingarm with rising rate linkages allows you to have greater control over the suspension attributes and also centralizes the mass / location of the shock parts. Is one better than the other? Well, the linkaged types are superior now mostly because no one uses the other type. All the development has been on linkaged style suspension.

It's a bit like USD forks V conventional forks - sure, you could probably make a set of conventional forks that are as good as USD's, but it's just old style technology and there's not much point when there's superior stuff readily available.
 

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Careful now Ken - you're in danger of going against your own mantra here and engaging the dancing monkey.

Using a swingarm with rising rate linkages allows you to have greater control over the suspension attributes and also centralizes the mass / location of the shock parts. Is one better than the other? Well, the linkaged types are superior now mostly because no one uses the other type. All the development has been on linkaged style suspension.

It's a bit like USD forks V conventional forks - sure, you could probably make a set of conventional forks that are as good as USD's, but it's just old style technology and there's not much point when there's superior stuff readily available.
Nope, I don't directly respond to dancing monkeys, but I do feel that it is OK to point out absurd statements regardless of who makes them. I have noticed that whenever I directly call my amusement on his obvious stupidity or lies he never answers the direct question. I don't expect a reply here, as you noted the advantages of a linkage style rear suspension outweigh the simplicity of the direct system. Would Moto GP, Moto2 or Moto3 use a linkage type system if the direct system offered any advantage over a simpler system?

Ken
 

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Discussion Starter #97
I guess we should make all our suspension decisions based on some street bikes and racing technology from 20 years ago. While it may be interesting what some mythical GP chassis guy knew about flexiflyer framed racebikes and give up trying to do anything better. However, I am a google image expert so I asked the Google about MotoGP rear suspensions and all the pictures of those bikes had fancy shocks with linkages and stuff. I wonder why. I will be curious what Tony Foale has to say about it since he is an expert and actually makes stuff. I bet he even has friends in the industry that aren't imaginary that know stuff, too. Did I mention that I raced against Tony at Mid-Ohio and then I visited with him in the pits while we looked at his frame that he built. Tony Foale exists, is a real person that impresses rather than amuses me.

Ken
thanks, I figure it will be more work to build a linkage but it will allow me to change the rate completely based on the rocker and link shape and size, seems direct connection doesn't give those kinds of options
 

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image3.jpeg image3.jpeg
is thius the look you are after ?

image1.jpeg

image6.jpeg

image7.jpeg

purchased from Queensland Australia
a long time back almost finished bike comleted just pulled back apart for final welding and paint should be done
when striping all paint off found the brand name Scorpion on head stem marked "Scorpion 01"
still have no info about its origins
 

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View attachment 99811

purchased from Queensland Australia
a long time back almost finished bike comleted just pulled back apart for final welding and paint should be done
when striping all paint off found the brand name Scorpion on head stem marked "Scorpion 01"
still have no info about its origins
Very interesting!

Hope to see it done soon...
 
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