SetUp - Race Reps versus Heavy Weight Bikes - ZRX1200

[oldninjaron]

Useage Thoughts

Front: Kawasaki quoted total stroke - 122mm. Actual measured 153mm, as indicated above internal "stoppers" make up the difference.

F1 - 153
F2 - 127 therefore Static sag 26mm
F3 - 108 therefore Rider sag 45mm

Useage 72mm

Static sag plus useage = 98mm therefore remaining stroke approx 122-98 = 24mm???? Seems excessive????

Rear: Measured total stroke on shock 92mm - includes 20mm rubber stopper.

R1 - 92mm
R2 - 87mm Static sag 5mm
R3 - 63mm Rider sag 29mm

Useage 53mm

Static/shock static plus useage=58mm therefore remaining stroke 92-58=34mm of which 20mm stopper leaves 14mm.

Thoughts anybody????

Edited by oldninjaron on Monday 21st September 07:20

Edited by oldninjaron on Thursday 24th September 18:46

[Steve Bass]

oldninjaron said:

Rider sag, settled on the following for now:

Forks: F1 = 153, F3 = 108 with preload 8 turns in from fully out therefore Rider sag = 45mm.

Shocks: Using measurements based around strut length only - rear suspension does not have linkage etc.
R1 = 91, R3 = 61mm therefore strut sag = 30mm equates to approximately third of available, includes rubber stop.

After good long ride using cable ties on forks and shock with the following rebound and compression settings:

Forks: Rebound = 10 clicks out of 15. Compression = 12 clicks out of 18.

Shocks: Rebound = 40 clicks out of 60. Compression = 16 clicks out of 24.

Useage

Front: 72mm, Rear 53

Felt a lot more confident although not perfect although having ridden the same road so many times I know where all the bumps are - even with rider sag set with no damping at all just to see how it felt when in a very loose state - felt like going back 30 to 40 years to my Kwack Z1000 days. With settings above it felt more controlled plus riding over longer bumps felt like front and back rising and falling approximately together. Before leaving, not very scientific I know with suspension warmed up an earlier run, noticed even just standing up and sitting down repeatedly front and back seemed to lower and rise about the same amount and approx same rate.

Any comments please about results above would be very welcome?

Edited by oldninjaron on Sunday 20th September 15:29

Edited by oldninjaron on Monday 21st September 12:52

Hi Ron, sorry, missed your updates.

Figures look good but perhaps try a little less front preload. If you've got a total of 153mm stroke available, I'd try to get around 55mm of rider sag. Looking at your numbers, you're only using ,120mm of the available stroke. Now not knowing if you still have bump stops in the front but I think you can afford to relax the front a smidge.
The rear seems good, but again, maybe open the rear sag to 35 to 40mm and see how it feels. If the springs are progressives, which were common on that era bike, you can afford more sag as the shocks and forks will stiffen at the end of the stroke.
Compression and rebound don't seem untoward, but only you can really judge what you like in terms of damping control. Have a look at the rear tyre sipes to see if there's raised edges on them, either leading or trailing edge. This will give you a good indication of rear rebound. On the front, feel if it's jumping back too quickly after braking and corner entry. Does it hold a line off the throttle when the brakes are released at turn in or does it jump back and feel vague on the front.

[oldninjaron]

Thanks for your comments, much appreciated.
When I bought the bike it came with modified forks - Maxton 0.97Kg/mm linear springs currently fitted, standard springs are progressive and I believe are 0.883 Kg/mm, revalved by the same company. Rear shocks are Ohlins which had springs suited to previous owner, approx 12 stone weight - I come in at approx 17 stone fully geared up so since had to wind in huge amounts of preload to get close to correct rider sag have swapped to stronger springs which has sorted that avenue - original Ohlins springs 20.3-28.6 Nm whereas current 24-33 Nm.

Withe current setup looks like I have approx 24mm still available at the front forks so I presume plenty to allow increase in rider sag - mind you that was based on 120mm approx total stroke, as per Kawasaki, rather than 153mm?

Does that make a difference to next step?

Edited by oldninjaron on Thursday 24th September 23:05

Edited by oldninjaron on Thursday 24th September 23:09

[Steve Bass]

oldninjaron said:

Thanks for your comments, much appreciated.
When I bought the bike it came with modified forks - Maxton 0.97Kg/mm linear springs, standard springs are progressive and I believe are 0.883 Kg/mm, revalved by the same company. Rear shocks are Ohlins which had springs suited to previous owner, approx 12 stone weight - I come in at approx 17 stone fully geared up so since had to wind in huge amounts of preload to get close to correct rider sag have swapped to stronger springs which has sorted that avenue - original Ohlins springs 20.3-28.6 Nm whereas current 24-33 Nm.

Does that make a difference to next step?

remember that winding in preload won't change the spring weight/strength. If you're too heavy for the springs, you're too heavy... end of.
If you have linear springs up front now that makes you life easier. For that type &weight of bike, and given the numbers you're mentioning, I'd look to relax the preload a bit more. On 153 mm of available front stroke, go for 50 to 60mm of sag. 90mm of stroke in the rear, go for 40mm. A bit of compliance on a big old bus like the ZRX won't hurt.
But don't get too hooked up on absolute numbers. The biggest thing is how it feels when you're riding. Does it feel planted and composed, does it maintain traction front and rear over the majority of road surface, does it behave consistently under braking or turn in. Does it feel good under hard acceleration, throttle application in a turn etc. These are far more important than absolute numbers.
Out of interest, do you know what the oil type and heights are in the front forks? Are they the same? What's the air-gap?

[oldninjaron]

[quote=Steve Bass]

...... big old bus like the ZRX......

Its true but the engine is everything as long as you can get it to handle. This bike's power to weight ratio bears little resemblance to factory machine though, bit of a heavy-weight wolf in sheep's clothing. Performance closer to its brother the ZZR1200, without the RAM air. Modular engine allows for useage of some parts from one to the other including pistons/barrels/cams/carbs/igniter with a few other enhancements etc I loved my old ZX10/ZZR1100s just hated the fairing etc - LOL.

[oldninjaron]

Steve Bass said:

remember that winding in preload won't change the spring weight/strength. If you're too heavy for the springs, you're too heavy... end of.
If you have linear springs up front now that makes you life easier. For that type &weight of bike, and given the numbers you're mentioning, I'd look to relax the preload a bit more. On 153 mm of available front stroke, go for 50 to 60mm of sag. 90mm of stroke in the rear, go for 40mm. A bit of compliance on a big old bus like the ZRX won't hurt.
But don't get too hooked up on absolute numbers. The biggest thing is how it feels when you're riding. Does it feel planted and composed, does it maintain traction front and rear over the majority of road surface, does it behave consistently under braking or turn in. Does it feel good under hard acceleration, throttle application in a turn etc. These are far more important than absolute numbers.
Out of interest, do you know what the oil type and heights are in the front forks? Are they the same? What's the air-gap?

My test ride route, must have been up and down it so many times, is a real mix of road, sharp short bumps shallow long bumps sharp bends and not.
Now that we are concentrating our efforts on the front using 153mm total stroke I can see where you are going with the rider sag - I will tweek front and back in that direction - 40 out of 90 equates to approx 44% of stroke available whereas 60mm out of 153mm aprox 40% of stroke available. Current settings rear 33% front 30% using 153mm for calculation. Weather expecting to pick up tomorrow we will see how she feels.

I am afraid inherited current fork oil and settings from previous owner but we are in touch - he has a later model of same with approx same spec engine - may have to speak to Maxton who modded forks albeit some time ago. I will let you know what I discover although perhaps time for new oil etc.

[oldninjaron]

Spoke to previous owner, good friend, he reckons 5W fork oil and air gap 160mm???

Tried to tweak rider sag front and rear as advised.
Forks:
Maximum rider sag possible - no preload - 58mm - 55mm = 1 1/2 turns in from fully out.

Shocks:
Tried backing off preload monitoring shock rod but despite lots of adjustment could not get it below 30 out of 90 so reverted to the standard way of measuring - vertical above rear axle to tape suitably positioned. Max rider sag, minimum preload, 43mm, so tweaked to 40mm.
It would appear measuring rider sag using shock rod unreliable just good for monitoring useage.

A difference of 15mm between front and rear must be too much - took bike out before it got too dark - felt every bump, bouncing about all over the place, unstable on the bends - nightmare. Definitely a backward step - cannot increase rear rider sag perhaps reduce front back down to 45mm?

[Steve Bass]

Rear sag must be measured at a point above the rear axle, NOT on the shock. Point of measure MUST be at the point of maximum leverage so make sure you stick to this. The wheel is further out back than the shock so measuring the shock will not give a worth while value.
The goal with a road ONLY bike is to have a bit more fork and shock extension due to the many more bumps and drops found on the road than on the track.
Once you have the sag setright,circa40-45% of total suspension stroke, then you can play with the compression and rebound.
As said above, don't get so obsessed with absolute mm measurements rather get in the range and then set the comp & rebound to suit. If in doubt, set the Comp & Reb to 50% and go from there.

[oldninjaron]

Does it mean that as unable to increase rear sag higher than 43mm, does this mean that rear springs need reducing to weaker lower rate springs?

I have a habit of learning the hard way

[Steve Bass]

Where are you measuring the 43mm? Above the axle or on the shock?
Typically, rear suspension travel is around 130mm so 43mm isn't too far out of the ballpark. IS your preload adjuster full in or full out in the rear to achieve the 43mm?

[oldninjaron]

Steve Bass said:

Where are you measuring the 43mm? Above the axle or on the shock?
Typically, rear suspension travel is around 130mm so 43mm isn't too far out of the ballpark. IS your preload adjuster full in or full out in the rear to achieve the 43mm?

Having discovered the hard way that using coil strut unreliable - reverted back to correct way above axle to point marked by tape on seat, directly above.

Reduced preload until could not increase rider sag any more and it would appear the coils were not far from no longer being held in place securely.
Coils are very easy to remove on these shocks, no compressor required just wind out preload until coil loose enough to come away from lower support which is then removed and coil then dropped off below. in reverse position coil with support underneath and wind preload until trapped by adjusting ring above and lower support.

[Steve Bass]

So 43 mm is the minimum sag you can achieve?
As a yard stick, measure the free uncompressed length of the rear springs. The wind in the preload so that the preloaded length is 12 to 15mm less as a start.
If you're getting 43mm out of a rough 130mm of travel, that should be fine. Tune the comp& reb until you are happy

[oldninjaron]

Thanks - should I be aiming to get closer to matching front and rider sag e.g aiming closer to 43mm in the front or leave at 55mm seems a big difference??

[oldninjaron]

Thanks - should I be aiming to get closer to matching front and rider sag e.g aiming closer to 43mm in the front or leave at 55mm seems a big difference??

[Steve Bass]

oldninjaron said:

Thanks - should I be aiming to get closer to matching front and rider sag e.g aiming closer to 43mm in the front or leave at 55mm seems a big difference??

No, not necessarily, I didn't say that. Stop getting het up about numerical differences. The total stroke front isn't the same as in the rear so the sag shouldn't be the same as an absolute mm number.
If the front has a total stroke of 153mm, 50mm is fine. Circa one third. If the rear has a total stroke of circa 130mm, 43 mm is roughly one third. Voila, you have balanced sag as a %age of available stroke, NOT absolute numbers.

[oldninjaron]

Thanks appreciate your help because as you can see from the myriad of updates on here have been lurching from one thing to another 1 step forward and 10 back. Few misconceptions along the way but it makes a lot more sense now.

[oldninjaron]

Very busy this weekend especially Saturday and missus needed a day out today so got to the bike late today.

First thing sorted today - noticed height adjusted on Ohlins so took them back down to factory settings do not want to take a chance with geometry.

Measured rear shock coils weight off - 230 mm as per spec, then refitted and wound preload on reduced length by 10mm. Strangely that released another 13mm rider sag at rear now max available 56mm - adjusted to 45mm.

Left rebounds front and rear at one third available and set compressions to 50%. Get out on the bike tomorrow.

[oldninjaron]

First run felt what can only be described as soggy, wallowing around bends the only bonus was that, despite feeling every bump, it was soft enough to be comfortable. The only time ridden it softer was when I removed all damping as an experiment - bouncy castle.
Next run I also tweaked rebound damping to 50% - started to be uncomfortable again all the bumps. Tweaked rebound back down to third available and then increased compression from 50 to 75% - awful over the bumps.

[Steve Bass]

Ron,

I get the impression you're swinging from one end to another in terms of the damping settings. You'll struggle if you do this.
Rather start at a point, say 30% and 50% rebound and compression and only add/remove at most 2 clicks either way. . Try it then adjust as necessary but make notes as to where you are in terms of settings and how it feels.
But throughout all this, you haven't said what you're actually trying to achieve? Suspension will always be a compromise between comfort and performance, and with a road bike, I'd say the former is preferable. It maybe that you will never arrive at a happy medium especially, as I said before, when you consider the size of the bike, the age and quality of the suspension.
Start to work methodically and pick what you feel is subjectively the best set up as the average.

[oldninjaron]

Roads are so uneven round here that comfort with sufficient control and confidence around the bends is key for me. Enjoyment for me riding bikes revolves around bends - straight bits are only stretches of road that link bends. I have the greatest trouble trying to work out what is causing my woes so of course, you ate right, only methodical route stands a chance its just knowing which direction and which adjustment to make.