Gen 4: 2011-2015 Anyone have some suspension geometry advice - Kawasaki ZX-10R.net
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post #1 of 68 Old 03-02-2017, 10:37 AM Thread Starter
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Anyone have some suspension geometry advice

Hi guys,

I have upgraded my shock to a Bitubo unit and due to mount it (now that I've figured out which way round it goes...long story).

The bike will be used mostly on track soon and a lot of guys shim the OEM shock by 8mm to improve the bike's handling.

Is this mainly because the stock shock is too soft causing the bike to sit a bit low at the back or is this a general change that would improve the bike regardless of shock?

Also I remember from my GSXR1000 (yes totally different) that many were setting the forks to flush with the yokes (US: triple clamps) and also extending the rear wheel all the way back in the swinging arm.

Now this sounds counterintuitive for a quick steering bike, but it was done to improve the GSXRs stability and for me made a good improvement.

Is there anything like this with the 10R that can make improvements to the stability as that is what I prefer on track to give me confidence.

Thanks.

Last edited by 10Arghh; 03-02-2017 at 10:40 AM.
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post #2 of 68 Old 03-02-2017, 04:06 PM
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Gen4 geometry thread is great, hoping to learn here.

Not suspention expert, but have tested several settings on racing Gen4.
Experts say (and they are correct) that there are 20, 50 or 100 "issues" and parameters all connected and affecting sportbike handling.
To name few: rider preference, riding style, tyres, level, weight. This all can set certail numbers to one or other extreme.
But I like numbers and what those "ballpark" numbers are, for example for average trackday frend.

These are few basics to think with Gen4:

*Shimming shock.
Good swingarm angle somewhere at 12 degrees. If it is too flat then rear compresses too much with acceleration.
If too much angle then shock extends "locks up", rear wheel wants to drive under engine.
At an optimal angle the rear suspention works midstroke (or upper mid) under acceleration, follows road and gives good contact and grip.
Measure your aftermarket shock length and spring preload before shiming as these measurements affect shimming directly.
Tyre sizes, front position, axle position affect this angle too somewhat.

*Wheelbase.
Longer wheelbase gives stability, but Gen4 has enough wheelbase and stability (due to much trail at front).
Tried to run axle almost all the way back with additional chain link and did not like it: made steering harder, numb and felt like I needed more lean angle to make same corner at same speed.


*Trail.
Gen4 has big trail number making it very stabile.
To go fast on race track you need to twist bars with much more muscle force than with CBR1000R or S1000RR having trail on other end of spectrum.
Shimming shock and dropping front reduces trail, but you get pretty quick to point where other problems surface.
This may win some 5mm trail, but cannot get to 100mm trail number this way.
I think that the only way TO TRY to make Gen4 nimble is with adjustable offset triple clamps, as this affect trail directly without spoiling other parameters too much.
Numbers: With race tyre, stock 26mm clamp and 25deg rake the trail is somewhere at 110mm.
Ducatis (like 1098, 1199) have similar big 24.5 rake, but triple offset of 36deg and popular mod was put 30mm clamps.
Early S1000RR had trail somewhere at 90mm (twichy) with steep rake and 32mm!! offset and benefited from offset at 28mm.
I'm not sure what adjustable offset camps will do to Gen4, but I will definetly try them this summer.
And clamps that will allow at least 30mm.

*Weight distribution.
Several problems when front or back too low or too high.
Rider body position and moving on the bike, training is important.
Besides maybe there is something special about Gen4 center of mass (engine position) that makes it get away with big trail, wheelbase and still steering reasonable, I dont know.

*Dynamic action.
Things like compressing suspetion too much, too little or moving rates way off.
If bike geometry is ok and you have problems at corner entry then its mostly fork problem and at exit shock problem.
Sping rates, preloads, rebound, compression are realated to eachother and without little experience bad settings are often seen.
Have help from profeesional if thinking to go fast on track. This saves tyre money, makes predictabel handling, safer and faster.
There is long Dave Moss video in Youtube (Suspension Tuning - Dave Moss Masterclass) explaings all the basics.

Race Gen4: K-teck DDS, OhlinsGP+link, RCS17+T-Drive, Kit ECU, MivvFull, ported, light crank, race int. cam.
Suzuki GSX1300R Hayabusa 2013
Kawasaki KX450F 2016

Last edited by Carlos76; 03-02-2017 at 04:19 PM.
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post #3 of 68 Old 03-03-2017, 09:33 AM
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Quote:
Originally Posted by 10Arghh View Post
Hi guys,

I have upgraded my shock to a Bitubo unit and due to mount it (now that I've figured out which way round it goes...long story).

The bike will be used mostly on track soon and a lot of guys shim the OEM shock by 8mm to improve the bike's handling.

Is this mainly because the stock shock is too soft causing the bike to sit a bit low at the back or is this a general change that would improve the bike regardless of shock?

Also I remember from my GSXR1000 (yes totally different) that many were setting the forks to flush with the yokes (US: triple clamps) and also extending the rear wheel all the way back in the swinging arm.

Now this sounds counterintuitive for a quick steering bike, but it was done to improve the GSXRs stability and for me made a good improvement.

Is there anything like this with the 10R that can make improvements to the stability as that is what I prefer on track to give me confidence.

Thanks.
www.suspact-na.com try this

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post #4 of 68 Old 03-03-2017, 12:12 PM Thread Starter
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Originally Posted by Carlos76 View Post
Gen4 geometry thread is great, hoping to learn here.
Thanks for detailed response Carlos...Seems you have done a lot of research with this bike.

My personal opinion, bearing in mind I haven't really tested the bike (no track day yet), it seems to turn in much quicker than the GSXR1000 K5. Running 190/55 rears on both, but different tyres and it's been over a year since I rode the K5.

I noticed this the first time I tried the 2011 ZX10R when it first came out.

Just something to get used to and I have already.

The front end feels wrong on my bike at the moment on stock suspension settings...Don't know how old the oil is but suspect its never been changed.

Pogo effect reacting to every bump and imperfection..Will try taking out some comp / reb damping.

Also could not get accurate sag setting.

Basically, the springs don't seem to react to weight being applied to them whether preload is taken all the way out or set all the way in.

All the way out, reduces the pogo effect slightly but there is still the damping problem.

The best I could do with the sag on the front was 22mm even with preload wound all the way in, also are the preload adjusters supposed to just keep spinning after they reach the max value on this bike?

Found that weird as the Ohlins R+T carts on my GSXR have a hard stop.

Anyway, so I think I need stiffer springs although the front feels rock solid and I'm wary of stiffening it further.

I have much work to do on the bike to set it up (slowed down by this charging system fault), but I believe the base is good as once settled in a turn feels very confident on the front.

This is all with using the stock shock at the moment as I have not fitted the Bitubo.

Need to fix all the electrical gremlins before tuning the bike.
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post #5 of 68 Old 03-03-2017, 01:13 PM
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Instead of guessing and speculating, lets just look at REAL numbers for the Gen 4 that I measured about a week ago.

A little about this bike. The suspension is 100% stock and the rider is racing with Pirelli Slick 120/70 and 200/60 slicks. While this affects geometry a bit the numbers won't be too far off from a bike on the showroom floor.



A couple things to notice -

-Trail is around 110mm. This means the front is very stable once in a corner, but entry into corners require more muscle to get in the corners.

- Rake is around 25 degrees, which is pretty good out of the box.

- Swing arm angle (swing arm down slope) is around 12 degrees. This isn't too bad, but add the long trail numbers and the bike has a tendency to drive wide on exit. Especially if the shock is under-sprung and/or heavy throttle is applied.
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post #6 of 68 Old 03-03-2017, 01:20 PM
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Next lets look at if we raise the rear.

Under the CMS measurement I add 20mm of ride height (approx 10mm at the shock).

This gives us a swing arm angle of 13.4 which in my opinion is a bit much. It also deletes trail almost 5 mil to 105.9, which again in my opinion is still a bit long. So with this setup the bike would turn much better, but the rider would probably complain about wheel spin while accelerating out of a corner.

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post #7 of 68 Old 03-03-2017, 01:24 PM
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So lets look at the other direction.

Here I lowered the front end by 10mm (Length front fork), or slide the tubes up in the triple by 10 mm.

You can see by lowering the front 10mm I really only deleted about 2 mm of trail. But look at the swing arm angle. I LOST almost a 1/2 of a degree of angle. So while the front end might feel a little better on entry, a rider will still complain about the bike driving wide on exit.

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post #8 of 68 Old 03-03-2017, 01:31 PM
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So what happens if we raise the rear 20 mm, and lower the front 10 mm. You can see we remove even MORE trail out of the front then either of the previous two, while not giving or losing too much swingarm angle.

I see a lot of guys here changing ride height front or rear without realizing why OR what else it affects. Also there are a BUNCH of other variables here, this is just scratching the surface but i figure this is a good visual to help people understand geometry.



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post #9 of 68 Old 03-03-2017, 03:12 PM Thread Starter
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This is great info

Think it should be made sticky.

So evallarta1 are you saying for most scenarios that the stock geometry can be left alone, if one just improves the rear soft shock that causes squat under acceleration causing the front to lift and the bike to run wide?

For my pace I believe that would work.
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post #10 of 68 Old 03-03-2017, 04:11 PM
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Quote:
Originally Posted by 10Arghh View Post
This is great info

Think it should be made sticky.

So evallarta1 are you saying for most scenarios that the stock geometry can be left alone, if one just improves the rear soft shock that causes squat under acceleration causing the front to lift and the bike to run wide?

For my pace I believe that would work.
I'll put it this way. If this were my bike, and I was doing anything but just cruising down the highway, I'd be figuring out how much trail to delete out of the bike.

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