Change fork reb target   this isn't used, delete later  
zeta_fkr_50-70.xlsx current fk reb target     .46-70s
  • chrtd = chrome tube drag
  • s = strait or linear
    • the zeta curve is mostly linear
  • 10 ips is focus for low speed r-zeta
  • Original baseline = .46-70s with 2.5 drag.
  • New baseline = .30-.65s to account for bushing drag.  See below.
zeta_backwards_fkc_fkr.xlsx change fk reb target    
  r-zeta factor    
   
openDynoFk__dyno_xplor.php  
 
  • Average seal drag is 4 lbs.  Bushing drag adds at least an additional 7 lbs.
  • No doubt the stock rebound valving over the years accounts for this.  But it is easy to dial in too much rebound.
  • Use these new r-zeta target to monitor rebound force at 10 ips.
  • Focus on 10 ips as critical for ls reb comparisons and small chop compliance.
    • Low speed reb is inherently stiff by design.  You can only reduce it so much at 1-10ips using stk components and typical valving configurations.
    • If ls reb is too stiff, run faster hs reb to compensate.  The stiff ls will catch reb overshoot.
    • 5-25-22 Current thinking after all this analysis, keep reb force same at 10ips and just run faster at 70ips. See fork whiteboard:  'new r-zeta for 5 lbs bushing drag'
  • Average cartridge tube rebound force for these r-zeta values with 2.5 chrtd.
    • .70 =    -19.2 (.96kg)     -18.2 (.88kg)
    • .65 =    -17.6 (.96kg)     -16.9 (.88kg)
    • .60 =    -16.0 (.96kg)     -15.3 (.88kg)
    • .55 =    -14.4 (.96kg)     -13.8 (.88kg)
  • Looking at AER and 4CS fork records.
    • fastest reb =  -15.0
    • stiffest reb =  -23.0
    • average =  -17.5 to -18.5
  • Looking at KYB fork records.
    • fastest reb =  -17.0
    • fastest reb =  -23.0
    • average =  -18 to -19
  • CONCLUSION: 
  • Basically we've come to the conclusion that r-zeta .70 isn't that far off.  We might want to go .65.
  • Consider test with these faster r-zeta targets.
    • r-zeta .49-.50s    as per 3201f  Matt Trimmier
    • r-zeta .49-.55s
    • r-zeta .48-.60s
    • r-zeta .48-.65s
  • See fork whiteboard:  'new r-zeta for 5 lbs bushing drag'
  • -
  • We used  3136f 18sxf350 Beavers  for the charts below.
  • ..
 
Rebound force at 3 - 10 - 40 - 70 ips compensate with compensate with
baseline +2.5 drag +5.0 drag lighter target reb factor x .92
r-zeta .70 reb up at 10ips reb still high at 10ips     reb same at 10ips
r-zeta targ .52-.70s r-zeta targ .52-.70s r-zeta targ .34-.70s r-zeta targ .34-.70s  
+0 +2.5 zeta +5.0 zeta +5.0 zeta +0 +5.0 zeta  
3ips = -5.2 -7.7 0.83 -10.2 1.10 -9.1 0.98 -3.8 -8.8 0.94  
10ips = -20.0 -22.5 0.73 -25.0 0.81 -23.7 0.77 -17.2 -22.2 0.72  
40ips = -84.6 -87.1 0.70 -89.6 0.72 -89.0 0.72 -77.2 -82.2 0.66  
70ips = -149.3 -151.8 0.70 -154.3 0.71 -154.3 0.71 -137.4 -142.4 0.66  
zeta drops .04 at 70ips
 
Rebound force at 3 - 10 - 40 - 70 ips compensate with compensate with
baseline +2.5 drag +5.0 drag lighter target reb factor x .92
r-zeta .65 reb up at 10ips reb still high at 10ips     reb same at 10ips
r-zeta targ .48-65s r-zeta targ .48-65s r-zeta targ .30-65s r-zeta targ .30-65s  
+0 +2.5 zeta +5.0 zeta +5.0 zeta +0 +5.0 zeta  
3ips = -4.9 -7.4 0.80 -9.9 1.07 -8.9 0.96 -3.6 -8.6 0.93  
10ips = -18.7 -21.2 0.68 -23.7 0.76 -22.6 0.73 -16.2 -21.2 0.68  
40ips = -78.4 -80.9 0.65 -83.4 0.67 -82.8 0.67 -71.6 -76.6 0.62  
70ips = -138.2 -140.7 0.65 -143.2 0.66 -143.2 0.67

-127.2

 -132.2 0.61  
zeta drops .04 at 70ips
 
Rebound force at 3 - 10 - 40 - 70 ips compensate with compensate with
baseline +2.5 drag +5.0 drag lighter target reb factor x .92
r-zeta .60 reb up at 10ips reb still high at 10ips     reb same at 10ips
r-zeta targ .48-.60s r-zeta targ .48-.60s r-zeta targ .33-.60s r-zeta targ .33-.60s  
+0 +2.5 zeta +5.0 zeta +5.0 zeta +0 +5.0 zeta  
3ips = -4.9 -7.4 0.80 -9.9 1.07 -9.1 0.98 -3.7 -8.7 0.94  
10ips = -17.5 -20.0 0.65 -22.5 0.73 -21.4 0.69 -15.1 -20.1 0.65  
40ips = -72.4 -74.9 0.61 -77.4 0.63 -76.8 0.62 -66.1 -71.1 0.57  
70ips = -127.4 -129.9 0.60 -132.4 0.61 -132.4 0.61 -117.2 -122.2 0.56  
zeta drops .04 at 70ips
 
Rebound force at 3 - 10 - 40 - 70 ips compensate with compensate with
baseline +2.5 drag +5.0 drag lighter target reb factor x .92
r-zeta .55 reb up at 10ips reb still high at 10ips     reb same at 10ips
r-zeta targ .49-.55s r-zeta targ .49-.55s r-zeta targ .34-.55s r-zeta targ .34-.55s  
+0 +2.5 zeta +5.0 zeta +5.0 zeta +0 +5.0 zeta  
3ips = -4.7 -7.2 0.78 -9.1 1.05 -9.0 0.97 -3.7 -8.7 0.93  
10ips = -16.3 -18.8 0.61 -21.8 0.69 -20.2 0.65 * -14.0 -19.0 0.61  
40ips = -66.4 -68.9 0.56 -70.3 0.58 -70.8 0.57 -60.5 -65.5 0.53  
70ips = -116.6 -119.1 0.55 -123.0 0.56 -121.6 0.56

-107.2

 -112.2 0.52  
zeta drops .03 at 70ips
 
Rebound force at 3 - 10 - 40 - 70 ips compensate with compensate with
baseline +2.5 drag +5.0 drag lighter target reb factor x .92
r-zeta .50 reb up at 10ips reb still high at 10ips     reb same at 10ips
r-zeta targ .49-.50s r-zeta targ .49-.50s r-zeta targ .35-.50s r-zeta targ .35-.50s  
+0 +2.5 zeta +5.0 zeta +5.0 zeta +0 +5.0 zeta  
3ips = -4.5 -7.0 0.76 -9.5 1.03 -8.9 0.96 -3.6 -8.6 0.93  
10ips = -15.1 -17.6 0.57 -20.1 0.65 -19.3 0.62 * -13.2 -18.2 0.59  * 10ips reb force with
  r-zeta targ .50 & .55 would
  never need to be reduced
40ips = -60.5 -63.0 0.51 -65.5 0.53 -65.1 0.53 -55.2 -60.3 0.49
70ips = -105.8 -108.3 0.50 -110.8 0.51 -110.8 0.51

-97.4

 -102.4 0.47
zeta drops .03 at 70ips