Gen 4: 2011-2015 Anyone have some suspension geometry advice - Page 4 - Kawasaki ZX-10R.net
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post #31 of 67 Old 03-04-2017, 10:57 AM
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Originally Posted by 10Arghh View Post
So evallarta,

Can you give me a baseline with my situation of Bitubo rear shock and OEM front set up?

I know you can't be precise, but if I lowered the front 5mm like mpp, what ride height should I set the Bitubo to given that 310mm is stock on that shock.

Thanks again for all the help and contributing to this thread.
Again, so many variables that you MUST take into consideration. This is why I sometimes hesitate posting "advice". Geometry is not a cookie cutter type situation, and anyone who says otherwise either doesn't know what they are doing or trying to rip people off.

In general, on the Gen 4, the front needs to be lowered, the rear needs to be raised. So you could lower the front, see how it feels, and then start adding rear ride height to the rear.

The point of putting this up is more of a starting point. By looking at the numbers, one can get a general idea of what they need to do. SO, in general the rear needs to be raised, the front needs to be lowered. Without measuring one's bike, it is IMPOSSIBLE of me to give you a "starting point"

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post #32 of 67 Old 03-04-2017, 11:50 AM
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Your issue is not the damper, or linkage, but insufficient support in the rear. When you accelerate the bike squats causing the front to lift giving it a "chopper" affect. The excessive trail gives you too much grip causing the bike to drive wide. The bad tire wear is from your lack of grip on side of the tire (no swingarm angle), is causing you to wait til you start to stand the bike up, then once you feel grip you wack the throttle and tear the tire. If you put swingarm angle in the bike it will allow you to get on the throttle earlier and ROLL instead of wack displacing the power throughout the tire range.

The instability in the front is from not enough spring support in the back. When you wack the throttle the bike over pitches to the back causing the front to come up too quick and give a "light" feel. Add some preload and get some swingarm angle in the bike and you shouldn't need a damper....
Im not sure all of that is my issue. I do roll on the power quite well but the tyre wears out so after a few sessions it becomes worn and then i have to put tc on 2 and stand it up and fire it out. I do believe it is undersprung at the back but i did have a gen5 shock in it with 110 spring fitted before. That was more supported for sure but the front was still waggling its head the whole time so i recon a bit more weight over the front would reduce that.
At brands hatch the bike was wheelieing down the back straight at 150mph which was causing me some scary wobbles.
The back straight goes over the crest so the front was always light.
More weight over the front plus less weight on my belly should help lol
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post #33 of 67 Old 03-04-2017, 01:35 PM
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Im not sure all of that is my issue. I do roll on the power quite well but the tyre wears out so after a few sessions it becomes worn and then i have to put tc on 2 and stand it up and fire it out. I do believe it is undersprung at the back but i did have a gen5 shock in it with 110 spring fitted before. That was more supported for sure but the front was still waggling its head the whole time so i recon a bit more weight over the front would reduce that.
At brands hatch the bike was wheelieing down the back straight at 150mph which was causing me some scary wobbles.
The back straight goes over the crest so the front was always light.
More weight over the front plus less weight on my belly should help lol

Preload. Putting on a 110 spring doesnt mean too much if you have little to no preload on it. EVERYTHING you're saying is telling me either spring, swingarm angle, or not enough preload. You already put on a 110 and it didnt help, so I would guess the bike is pitching too much due to lack of preload. This would also cause driving wide due to not enough swingarm angle dynamically.
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post #34 of 67 Old 03-04-2017, 06:37 PM
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I do believe it is undersprung at the back but i did have a gen5 shock in it with 110 spring fitted before.
I agree with Evallatra that reason for problem may be not enough swingarm angle or/and not enough preload.
But there is one more suspect there: "Gen5 shock compression valving (stacks)".
Your custom linkage is somewhere between gen4 and gen5 ratios (what are ca. 11% different for move and force). Your 15 stone weight and stronger link is clearly overpowering (blows through) compression system of the Gen5 stock stock. Use of Gen5 link should make improvement as force causes more shaft movement, therefore easier on compression valving.
Speaking from experience: I'm 83kg and I raced 2015 with stock link and standard valving Ohlins shock. Had always little or more that little tyre tearing, no matter what spring, tyre, tyre pressures, clickers or temperature. Thought that maybe it is normal for my weight racer. For 2016 upgraded to MSS replica link and revalved according to LDH suggested C37 compression stack and magic happened: no more tearing, not even with Pirelli SC1 in cold.
Just want to say how important rear compression valving can be for high power bike and over average weight.

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post #35 of 67 Old 03-04-2017, 07:01 PM
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I agree with Evallatra that reason for problem may be not enough swingarm angle or/and not enough preload.
But there is one more suspect there: "Gen5 shock compression valving (stacks)".
Your custom linkage is somewhere between gen4 and gen5 ratios (what are ca. 11% different for move and force). Your 15 stone weight and stronger link is clearly overpowering (blows through) compression system of the Gen5 stock stock. Use of Gen5 link should make improvement as force causes more shaft movement, therefore easier on compression valving.
Speaking from experience: I'm 83kg and I raced 2015 with stock link and standard valving Ohlins shock. Had always little or more that little tyre tearing, no matter what spring, tyre, tyre pressures, clickers or temperature. Thought that maybe it is normal for my weight racer. For 2016 upgraded to MSS replica link and revalved according to LDH suggested C37 compression stack and magic happened: no more tearing, not even with Pirelli SC1 in cold.
Just want to say how important rear compression valving can be for high power bike and over average weight.
While valving "may" be an issue I don't know if it would be the complete case. I have guys running ohlins shocks out of the box on pirellis and no tearing. The one thing you did not mention is playing with ride height to get more swingarm angle.

If you run on long corners where you're on the side of the tire valving is not going to do anything, because the suspension is not moving, spring position holds all that.

While C37 does have more low speed compression, I feel there are a few more parts of the equation you might be missing.

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post #36 of 67 Old 03-04-2017, 07:30 PM
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Just little more preload and rule that go two steps down with spring as big change in link ratio.

My notes were following:
2015 - stock link, std. valving Ohlins, 115 or 110 spring, 13mm preload, 314mm shock length: allways little tearing.
2016 - MSS link, C37-R5 Ohlins, 105 spring, 15mm preload, 314mm shock length: no tearing anymore, grip is better, drive is better, TC activates later.

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post #37 of 67 Old 03-05-2017, 03:00 AM
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Originally Posted by Carlos76 View Post
I agree with Evallatra that reason for problem may be not enough swingarm angle or/and not enough preload.
But there is one more suspect there: "Gen5 shock compression valving (stacks)".
Your custom linkage is somewhere between gen4 and gen5 ratios (what are ca. 11% different for move and force). Your 15 stone weight and stronger link is clearly overpowering (blows through) compression system of the Gen5 stock stock. Use of Gen5 link should make improvement as force causes more shaft movement, therefore easier on compression valving.
Speaking from experience: I'm 83kg and I raced 2015 with stock link and standard valving Ohlins shock. Had always little or more that little tyre tearing, no matter what spring, tyre, tyre pressures, clickers or temperature. Thought that maybe it is normal for my weight racer. For 2016 upgraded to MSS replica link and revalved according to LDH suggested C37 compression stack and magic happened: no more tearing, not even with Pirelli SC1 in cold.
Just want to say how important rear compression valving can be for high power bike and over average weight.
I tried the standard gen5 ratio side plates on my bike but it was way too hard but i think its because my plates run the standard gen4 dogbone.
I have a complete gen5 link which i can fit when my bike comes home from mss.
To be clear the gen5 shock setup was the best ive had so far for tyre wear but the rear was a little soft for my weight causing the front to come up more. I fitted 110 spring and the front came up less but tyre wear went up slightly.
Then i fitted a mupo shock and tyre wear is worse but i think its because the shock must have been valved for a mss race link as damping feels less than a gen5 shock. Unfortunately the seller couldnt confirm what link the bike had so its all guesswork for me.
Im not racing so its not too much of an urgent issue for me but longer tyre life is something i long for on trackdays.
I had my ideal oppourtunity to prove myself against racers at a track day last year but just couldnt as this happened to my virtually new tyre in just 3 sessions so could barely keep up.

Last edited by ukzx10r; 03-05-2017 at 05:23 AM.
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post #38 of 67 Old 03-05-2017, 05:52 AM Thread Starter
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This should help you ukzx10r
https://lifeatlean.com/motorcycle-tyre-wear-guide/

When are you next going to Brands? Im thinking of booking the GP day with No Limits 3rd May for 179

Need to get the bike dialed in first.
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post #39 of 67 Old 03-05-2017, 12:19 PM
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Just to reiterate from EV that any suggested starting points are just that, starting points. You may or may not end up anywhere near those starting points for your intended use and speed. Put it this way, if there is an optimal geometry for everyone all the time...why wouldn't the manufacturers just build it that way in the first place? Or at least offer the parts and settings in their race "kit" catalog.

From my own experience, I can tell you that I was fastest with a "nose heavy" geometry on 3 different race bikes. I made the mistake of going to suggested baseline geometry settings from top tuners several times and being slower on track. EV is 100% right, if you are chasing seconds and 10ths on the track you have to have the knowledge in your pit to make positive improvements. If you don't have it, hire it and experiment.

Suspension is important but so is riding style, track temp, tire, compound, pace, and tire pressure when diagnosing tire wear. Do not take suspension and geometry as the end-all be-all of tire wear indicators.

Finally, I don't believe in preload for anything other than dynamic chassis geometry tuning.

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Last edited by sdiver68; 03-05-2017 at 12:26 PM.
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post #40 of 67 Old 03-05-2017, 12:31 PM
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Quote:
Originally Posted by ukzx10r View Post
I had my ideal oppourtunity to prove myself against racers at a track day last year but just couldnt as this happened to my virtually new tyre in just 3 sessions so could barely keep up.
You could just go do a race and prove yourself when they're racing...;)

Take your shock off and have it serviced and setup for your application or it's just a blingy waste of money.
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