Motion Control Single adjustables installed
#165
Re: Hysteresis due to N2 charge:
At least on mountain bikes it's really hard (impossible) to differentiate between hysteresis and changes in spring rate. Basically the N2 charge is acting like a small air-spring, which gets added to your regular spring while in use. And since Miatas are running 400 lbs/in springs and up- you probably won't notice the N2 charge adding 20-30 lbs of spring rate.
On bikes our gas-charge starts at 500 psi for certain shocks and can go upwards of 3000 psi at bottom-out (due to extreme packaging restrictions). In the end- it doesn't affect the ride quality. The normal spring is providing so much greater force that you end up not noticing the gas ramp.
TL;DR Don't worry about Hysteresis.
At least on mountain bikes it's really hard (impossible) to differentiate between hysteresis and changes in spring rate. Basically the N2 charge is acting like a small air-spring, which gets added to your regular spring while in use. And since Miatas are running 400 lbs/in springs and up- you probably won't notice the N2 charge adding 20-30 lbs of spring rate.
On bikes our gas-charge starts at 500 psi for certain shocks and can go upwards of 3000 psi at bottom-out (due to extreme packaging restrictions). In the end- it doesn't affect the ride quality. The normal spring is providing so much greater force that you end up not noticing the gas ramp.
TL;DR Don't worry about Hysteresis.
#166
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Thank you for the detailed explanation, Emilio. When or if I get serious about my track days I feel confident the Xidas are the best choice available due to the time and effort spent to develop them. I appreciate your efforts to develop products for the platform.
#170
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That's not it. Its the difference between accelerating and decelerating. Not 2 whole separate cycles. I think (same not knowing anything about shocks applies to me)
#171
From the article: What is Hysteresis?
Hysteresis is lag in response of a damper usually due to compressibility of damper fluid from high pressures in the damper.
I know penske is obsessed with hysteresis reduction and pressure balancing and the like, but most of our performance gains (rock shox) come from reducing friction throughout the system, and keeping dirt out and oil/air in.
That said Penske is making shocks that cost $50000 a corner and we make shocks that cost $150. BIG difference.
#172
By reducing the length of the rear Xida body for the NA/NB to get our desired bump/droop ratio, we were accepting a steeper nitrogen pressure ramp at full compression. Xidas are filled to about 15 bar (217psi) of N2 The rears will increase to as high as 25 bar (362psi) at full bump. This increase in pressure effectively changes the compression damping towards full bump the same way a remote reservoir does. A longer, higher volume body (front NA/NB Xida) still increases nitrogen pressure from 15 to about 17bar. A damper filled with only say, 6 bar will have a lot less hysteresis potential. MCS appear to be 12 bar (175psi).
#173
Trust me, if there were a simple solution to the packaging issues on the NA/NB rear, we would have found it about two decades ago.
In any case, there isn't as much of a compromise as you might think. Xidas work exceptionally well. IOW, don't overthink it.
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#174
I think the reason that some shock tuners may try to limit hysteresis is that: it is easier to tune a shock by turning an adjuster... say one click, and then know to expect... say a 25# change across the entire working range of the shock, than it would be to try to work with a non-linear adjustment (high hysteresis shock).
#177
As I pointed out earlier, the twin tube shocks on the ND are superior to Penske shocks on the NC, therefore $25 twin tube shocks are the superior shocks. All kidding aside, the shocks can't fix a poorly designed suspension. There really isn't any "best" shock. It all depends on which metric you are measuring.
#178
Bit of a thread resurrection: does anyone know whether the MCS shock dyno plots in this thread are for a front or rear shock?
I'm trying to come up with a 'off the shelf' bilstein shim stack (or a couple for diff spring rates) everyone in the budget/ebay bilstein threads can use - there's heaps of places that will revalve a bilstein cheaply, the difficulty comes in knowing what to specify.
From what I can tell both XIDAs and MCS are both using similar valving - both digressive (assuming something sensible happens off the scale shown on the MCS graph which only goes to 5IPS), both similar forces:
(I've overlaid the MCS full soft/full stiff from this thread on the front xida plot, but the MCS graph may actually be for a rear...)
I'm trying to come up with a 'off the shelf' bilstein shim stack (or a couple for diff spring rates) everyone in the budget/ebay bilstein threads can use - there's heaps of places that will revalve a bilstein cheaply, the difficulty comes in knowing what to specify.
From what I can tell both XIDAs and MCS are both using similar valving - both digressive (assuming something sensible happens off the scale shown on the MCS graph which only goes to 5IPS), both similar forces:
(I've overlaid the MCS full soft/full stiff from this thread on the front xida plot, but the MCS graph may actually be for a rear...)
#180
Fair enough - I was thinking they may digress after what's shown on the graph (5IPS) at least for rebound - it doesn't really matter though. Either way, the forces are pretty similar under 5 IPS (in the bleed range shown), so I'm interested in whether the graph posted for the MCS was a front or rear.