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Discussion Starter · #1 ·
Totally twisted idea that brings a twisted simle to my face, just a twisted thought:

For a TLR, for stunting with a heavy guy like me, on a bike where you care little enough about weight to be running a steel-pipe stunt cage and sliders everywhere...

Or, if not for stunting, double shocks might be an interesting option for controlling an extended swingarm. But not for drag racing, too heavy and no point since the shock doesn't get hot enough to fade in 1/8 1/4 or 1/2 mile.

How about two rear shocks, but hardly old-school rear-mount outboard duals. There's certainly room for two big ones under the seat! The TL is wide to accomodate stock SOAS and rotary damper, might as well use the space that's there!

A Bitubo in the stock SOAS location, with the softish Bitubo spring, and set to minimum compression and rebound damping. Kind of like an upgraded SOAS with some damping. Weight comparable to the stock SOAS, maybe a hair more.

Then also add an Ohlins kit in place of the rotary, except with the softest spring you can find to fit the Ohlins. Weight a lot less than the stock rotary and linkage.

That way it keeps some of the original stock system's use of the progressive linkage for most of the springing but straight connection for most of the damping.

Did I mention that I like a stiff rear?

It would still weigh less than the stock mess. It would never fade, it would have double the area to dissipate heat. It would be very strong and difficult to bottom when landing high stoppies with both springs. Might think it would be too much high-speed compression damping, but perhaps not. Opening the low-speed circuits on the Bitubo would also bypass and lessen the high-speed damping, so it barely counts, it's just a damping helper to the Ohlins, really just a more helpful SOAS used like this. Both stacks would pop at their original compression-speed rate, the Bitubo a bit later 'cause of the bypass. The additional force to operate the second stack might be inconsequential. I'll bet that the high-speed damping would be OK too, because the real limit to high-speed movement is when the valve orifices start operating way into their non-linear range and approaching hydraulic lock...none of that would be affected, in fact using both together, each would have its bypasses adjusted a bit more open (especially the Bitubo), so they would each have less high-speed damping than normal, so the high-speed damping would not really be doubled.

I guess ideally perhaps both should have their stacks re-thought and re-shimmed.

The stiction would be double, but still less than the stock mess.

And of course I'd wrap that rear exhaust pipe and add some kind of heat shield to protect the shocks from the heat of the pipe. That's a lot of money in them-thar dual shocks.

Now, with that much spring and damping, I could consider things like changing the leverage and increasing the swingarm travel too. Expecially since I use these huge front and rear sprockets, there's no chain interference. Not a huge increase, but enlarge the holes off-center in the swingarm mounts and insert bushings, just enough to move the center over a little. Maybe figure out which shock bottoms out or tops out first, and adjust them to limit together. Maybe weld a slight extension onto the swingarm, about another inch, not enough to keep it from wheelieing on command.

From a strength standpoint, this would go along with my forged CZ stage 2 aluminum wheels which are really strong. And if you never bottom, you probably never damage your wheels.

Or it could be folly and stiff as a rock unless half the shims are removed from the Bitubo stack.

But there are advantages to using two like this. They are not matched like old-school duals. One big advantage might be that there's not one single stack popping, a partially-open stack only seems to work partially over a small speed range, they use the word 'pop' for a reason. With two stacks, you could get the damping to change twice, acting more smoothly over a broader range, opening for a bump more smoothly.

I'd really like to experiment and give it a try.
 

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Seems like it would work just fine although it seems a bit overkill. Do you think you'd not be able to get enough damping out of one shock or would overheat and fade one shock? I would have thought that stunting wouldn't normally generate much shock heat and you should be able to re-valve a shock to have about as much damping as you could ever want:O IMO it physically would work just fine as far as I know, but the performance benifits are dubious at best to me:)

Oh, with multi-shim valve stacks they don't just pop open all at once but more or less progressively open up to the best of my knowledge.


have fun:thumbup
 

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a little FYI...my ohlins setup, with brackets, etc, wighed just about as much as the stock SOAS and rotar setup did :O
 

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Discussion Starter · #4 ·
TLR-Billbo said:
a little FYI...my ohlins setup, with brackets, etc, wighed just about as much as the stock SOAS and rotar setup did :O

Yeah, it's probably not practical nor efficient. Jus tcan't stop myself from getting these weird ideas. Perhaps "less is more"
 

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