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Discussion Starter · #4 ·
Tank mounts and seat rails in place. Still a long road but it's nice to see the seat line finalized. There will be an additional brace underneath curving away from the arch of frame's backbone but it won't disrupt that wheel-seat gap very much.

 

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Have you done the math on the changes to the geometry of the bike/suspension?
 

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I am wondering about the rear shock as well. It appears like the forward mounting point should be higher to meet the tangents of the main swingarm pivot point.

Are those GSXR 1000 forks?
 

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Discussion Starter · #9 ·
I can't picture how the rear suspension is going to work. It doesn't look like it is going to compress the shock so much as bend and pinch it.
I am wondering about the rear shock as well. It appears like the forward mounting point should be higher to meet the tangents of the main swingarm pivot point.

Are those GSXR 1000 forks?
The people struggling the most with how the rear suspension works seem to be stuck on the notion that the rear suspension travels upward in straight lines. Everything on the rear suspension travels in arcs. As the suspension compresses, the swingarm mount travels in an arc around the pivot. The frame mount for the shock is above the pivot. As the swingarm swings the distance between the mount on the swingarm and the frame mount gets smaller. Both ends of the shock are also on bearings just like it is on other bikes. There is no pinching or bending...the swingarm swings, the shock compresses. Despite how it looks, it is a 100% conventional direct-mount suspension...I just braced the swingarm and raised the mount very high off the radius so I could get the shock mounted in a better location functionally, a more interesting location aesthetically, and able to work with a much bigger lever against the swingarm than it would have had if I had mounted the shock against the arm and backbone.

One of my biggest sources of amusement here is that everyone seems to be flipping their lid over that shock but had mounted against the swingarm and backbone like a good boy no one would have batted an eye. No one would have even noticed. Sure it would have taken a 35kg/mm spring to do it but that wouldn't have even crosses anyone's mind...everyone would have just seen it as normal and moved on lol

Forks are triumph 675R, Tinsnips.
 

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Discussion Starter · #10 ·
What are your numbers in terms of geometry in rake and trail?
Have you done the math on the changes to the geometry of the bike/suspension?

Sorry miniman2 I didn't see your question previously!

Rake and trail are a little up in the air until I get my rear sorted out but it's going to be be in the area of 28~30 degrees and roughly 100mm.
 

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Discussion Starter · #13 ·
I'd be more concerned about frame fractures, it's not like it would be the first motorcycle to ever develop them.
of all the concerns people have yelled about the shock this is the one i wish people were aware of. The shock works, the mounts work, the only thing thatI’m concerned about is the frame holding up to it where i have it mounted...crummy bit is the pnly way i can find out is by riding it. I will be watching it very closely.
 

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of all the concerns people have yelled about the shock this is the one i wish people were aware of. The shock works, the mounts work, the only thing thatI’m concerned about is the frame holding up to it where i have it mounted...crummy bit is the pnly way i can find out is by riding it. I will be watching it very closely.
Actually, you could do destructive testing if you had another frame that you could write off.

Frames crack more near the countershaft sprocket from what I seen. Or the steering head, but you also have a saddle that has to carry people and that's a big lever.
 

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On modern frames, that narrow backbone part of your frame is a substantial alloy casting that everything is bolted to and it is as wide as the swingarm with 2 sides. Lots of triangulation calculated in to deal with the forces of your engine basically trying to twist itself out of the frame.
Crankset Automotive tire Motor vehicle Bumper Automotive exterior
 

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I can't picture how the rear suspension is going to work. It doesn't look like it is going to compress the shock so much as bend and pinch it.
it will compress it, I've done the math based on pictures and the shock specs, he's got a 150lb/in wheel rate on a bike that when stock weighed 550lbs, not sure how much lighter it may be now, but that's a very soft rear end, lever ratio also goes up as it compressed, so with 5" of compression of the wheel, you've got a 120lb/in wheel rate
 

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Discussion Starter · #20 ·
it will compress it, I've done the math based on pictures and the shock specs, he's got a 150lb/in wheel rate on a bike that when stock weighed 550lbs, not sure how much lighter it may be now, but that's a very soft rear end, lever ratio also goes up as it compressed, so with 5" of compression of the wheel, you've got a 120lb/in wheel rate
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
 
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