Rear suspension dynamics issue.

[4agshoob]

I hope this is the right place.

Anyway im in the midst of building my custom chopper. I have the rear suspension pivoting and working so efficient, that im bottoming out a 850lbs. Mountainbike spring. I weigh 250 lbs myself, and sit forward of the swing arm pivot.

I really dont want to result to a cantilever setup, because it will take room in the area of my jack shaft. I was orginally going to run dual shock setup but decided against it in the name of clutter And there again them being in the way of the chain drive and jack shaft.

Ideas?

 

[user 135]

Can you weld your lower pivot onto the chainstay instead of that 2-3" extension? Then flip the bolt on anchor points to get the shock further forward. Less leverage= stiffer

 

[4agshoob]

Can you weld your lower pivot onto the chainstay instead of that 2-3" extension? Then flip the bolt on anchor points to get the shock further forward. Less leverage= stiffer

Possible, but with this 7" shock, my frame would be 1" from the ground, before i sat on the bike, resulting in ultimatlely laying frame with my weight on it.

 

[4agshoob]

I came up with a linear dual coil setup.... im going to play with the cantilever angles and see what i come up with... as of right now, the rear shock would still be recieving the blunt of the load.

If i welded tabs to hold a second shock up on the top tube, i could have linear dual cantilevered shocks.

 

[user 135]

Pretty sure that Shock #1 will still be overworked as not much changed. If you have 2 shocks in the front, then you should remove shock#1 and make that a static linkage.

 

[user 135]

Lot more info here about how it all works. Kinda techie. http://ffden-2.phys.uaf.edu/211_fall2010.web.dir/Michael_Stanfill/Designs.html

A nice writeup about the different styles. Non techie. http://www.bikeradar.com/gear/article/buyers-guide-to-mountain-bike-suspension-part-2-28438/

 

[4agshoob]

Well i added a tab a bit closer toward the pivot. Heres the new angle:

This angle works a bit better. Spring is still too soft. However, i can run dual side x side springs in this position, with those brackets, and still clear everything for the jack shaft and chain drive.

 

[4agshoob]

Lot more info here about how it all works. Kinda techie. http://ffden-2.phys.uaf.edu/211_fall2010.web.dir/Michael_Stanfill/Designs.html

A nice writeup about the different styles. Non techie. http://www.bikeradar.com/gear/article/buyers-guide-to-mountain-bike-suspension-part-2-28438/

Great links!! Thanks!!!

 

[4agshoob]

Can you weld your lower pivot onto the chainstay instead of that 2-3" extension? Then flip the bolt on anchor points to get the shock further forward. Less leverage= stiffer

Ahh, i see what your saying now, the lower "swing arm" pivot. The silver section is the actual pivot, and it is bolted to the black part that is welded onto the OCC chainstay. I tried it the other way on the initial tacking of the bike, and it made the back wheel at a funny "jacked up" angle.