[Kiwi Rider]

I've had to learn a bit about this subject in the last three years since I got into racing and I've been fortunate to have a couple of old hands at the game mentor me through it.
Previous to this I viewed suspension set up as a bit of a dark science, mainly because I didn't understand it.
I'm not saying I know it all now though - far from it. Just the other day I got a good tip off member @Engine-R about only doing your suspension adjustments when the suspension oil has been warmed up. Makes sense as this is the state the suspension will be in when your riding.
So I'd like to pass on a couple of things I've learned regarding the basics of setting up a race bike with adjustable suspension and also some of the mistakes I made.

Lets start off with the first assumption/mistake I made: Hard is good, soft is for road bikes. These days I'm running double the amount of static sag I was when I first started out and (on my SV) I have changed both front and rear springs for softer ones. Result: My lap times have improved and I now have better front end feel.
That rigid feel may be good for lessening pitching, nose dive under braking and wallowing but lets face it, how many tracks that we ride on are billiard table smooth? When your cranked right over and you hit an imperfection in the track if your suspension cant absorb some of that then your going to bounce of it and lose tyre contact knocking you off line and unsettling the bike, which in turn will unsettle you!
You also dont have that same feel of just how much your pushing the front end when its set up stiff and remote like.

So much of getting the correct set up is about spring rate. You must be prepared to change your springs to suit your body weight. After setting my spring preload to get the correct amount of static (bike) sag my rider sag figure was still too little because I'm a light weight. I tried to race it like this rather than invest in springs of the proper rate (and also because I thought hard = good) but ultimately I had to change my springs. Same goes if your a heavy weight. Screwing up your preload adjusters until you see better sag figures and turning your compression and rebound damping up is only going to mask the underlying issue that your spring rate is wrong for your body weight.

Setting your sags: First time I ever went to do this I couldnt work out why there was only about 1 mm difference between my unloaded figure and my static (bike weight only) figure no matter how much I adjusted the preload adjuster. Reason: I was using the paddock stand to unload the rear shock and of course this does not do that. Sure, the rear wheel comes off the ground but the suspension is still not unloaded because I wasn't holding the bike up by the foot pegs. Seems obvious now huh.

Static sag is the difference in measurement between that fully unloaded state I was struggling to find (topped out) and then measured again with the weight of the bike on the suspension.
Rider sag is taken using that same first unloaded measurement as a baseline and then re-measuring with the rider sitting on the bike and calculating the difference.

Front suspension is easier to measure because you just measure the amount of chrome showing on the stanchions. Make sure though that your using a stand that lifts underneath the steering stem to fully unload the suspension.
On the rear I like to stick a piece of pointed sticky tape directly above the rear axle nut on the tail section. Then I just rest the tape measure on top of the axle nut and measure up to the piece of tape. Its easier if you have someone to hold onto your bike for you.

Easiest way to get your rear end fully unloaded for measuring and working on the suspension is to lift it up on the paddock stand then slip two of those cheap automotive axle stands under each of the foot pegs (only works if you have solidly mounted foot pegs like on rear sets) now let the paddock stand down and you are good to go.

I'm almost reluctant to suggest sag figures as there are lots of personal opinions on this but, as a guide only:
Static: front 20 - 25mm, rear 5 - 10mm (I use 10, helps keep rear wheel on ground under heavy front braking)

With rider: (wearing all gear inc helmet) front 35 - 40mm, rear 25 - 30mm

Set your static sag up first using your preload adjusters then adjust your rider sag by changing your springs if need be.
As you can see the front requires considerable more sag than the rear end to be effective.

When measuring rider sag I get someone to do the measurements while I lean my elbow ever so slightly on an adjacent wall to hold the bike up. A third person is even better for doing this job though.

Something else that I'd like to mention is front fork friction.
After fitting the front axle you need to leave the pinch bolt loose until you have tightened the axle nut or screwed the axle fully into the fork leg depending on your set up. Then drop the front wheel off the bike stand and bounce on the front end a couple of times. This aligns the forks properly and now you can tighten the axle pinch bolt. Your forks will slide best in this position with least friction.

I think I will save damping for another night. To be continued

 

[SDM!]

Subscribed

Now you have me wondering about my cartridge springs, I ordered for my weight 100 - 110 Kilos. Maybe I should have done a 90 - 100?

About this

I'm almost reluctant to suggest sag figures as there are lots of personal opinions on this but, as a guide only:
Static: front 20 - 25mm, rear 5 - 10mm (I use 10, helps keep rear wheel on ground under heavy front braking)

With rider: (wearing all gear inc helmet) front 35 - 40mm, rear 25 - 30mm

This is for your weight? Or just a basic beginning point?

I'll be waiting for the next episode

 

[Kiwi Rider]

Subscribed

Now you have me wondering about my cartridge springs, I ordered for my weight 100 - 110 Kilos. Maybe I should have done a 90 - 100?

About this

I'm almost reluctant to suggest sag figures as there are lots of personal opinions on this but, as a guide only:
Static: front 20 - 25mm, rear 5 - 10mm (I use 10, helps keep rear wheel on ground under heavy front braking)

With rider: (wearing all gear inc helmet) front 35 - 40mm, rear 25 - 30mm

This is for your weight? Or just a basic beginning point?

I'll be waiting for the next episode

No these figures are what you are aiming for regardless of your weight. This is where the spring rate comes into it. Yes it's a bit of a pig and a poke (kiwi expression maybe?) when ordering springs I know. Once you know exactly what you have on the bike it makes it easier though. The Ohlins and K-tech rear shock springs have numbers stamped on them. The last two numbers is the spring rate from memory. Unfortunately the race tech front fork springs I use do not so you have to keep the box they came in!

I went from .95 kg/mm front springs down to .85 kg/mm
On the rear I went from a 9.5kg /mm Ohlins down to a softer 8.5 kg/mm K-tech spring.

 

[Kiwi Rider]

Pt II Damping

Damping is basically controlling the action of the suspension through the use of oil being forced through shims and orifices. If we didn't have it your bike would bounce around like it had pogo sticks at each end of the bike.
Changing the size of the hole or orifice so that the oil can flow through quicker or slower is a crude way of explaining how damping adjustment works! I'm no technical suspension guru.

Once you've got your bike sags set up correctly and spring rate sorted then the fine tuning comes from the damping adjustments.
The best way to do this is through trying out different settings and seeing what works best for you and your own riding style.
Before you start twiddling with the knobs willy nilly though take a note of what they are set to at the moment and write it down. Then you will have a point of reference you can return to if you end up with an un-ride-able mess!
Count the number of clicks it takes before the adjuster stops turning in a clockwise direction. This is the fully screwed in position with maximum damping. Write that number down and then return the adjuster knob back to where it was before by turning it anti clockwise.

Have a ride on the bike and note any characteristics you dont like about what it's doing. Then go to the trouble shooting guide below which I think is the best one I've come across and use all the time:

Suspension Troubleshooting Symptoms

Here are some basic symptoms of damping problems that might be affecting your bike. Remember, these are extreme examples; yours may be more subtle. You may have to find an acceptable compromise on either end of the adjustment spectrum. It all depends on how the bike's handling feels to you.

Lack Of Rebound, Fork
* The fork offers a supremely plush ride, especially when riding straight up. With higher speeds, however, the feeling of control is lost. The fork feels mushy, and traction feel is poor.
* After hitting bumps at speed, the front tire tends to chatter or bounce, and the fork has a wallowy, loose feel.
* When flicking the bike into a corner at speed, the front tire begins to chatter and lose traction. This translates into an unstable feel at the handlebar.
* As speed increases and steering inputs become more aggressive, a lack of control begins to appear. Chassis attitude (sudden changes in pitch) becomes a problem (front-end wallowing), with the front end refusing to stabilize after the bike is steered hard into a turn.

Too Much Rebound, Fork
* The ride is harsh. Rough pavement makes the fork feel as if it's locking up with stiction and harshness.
* Under hard acceleration exiting bumpy corners, the front end feels like it wants to "wiggle" or "tankslap." The tire feels as if it isn't staying in contact with the pavement when on the gas.
* The harsh, unforgiving ride makes the bike hard to control when riding through dips and rolling bumps at speed. The suspension's reluctance to maintain tire traction through these sections erodes rider confidence.

Lack Of Compression, Fork
* Front-end dive while on the brakes is excessive.
* Rear end of motorcycle wants to "come around" when using front brakes aggressively.
* Front suspension bottoms, with a solid hit under heavy braking and after hitting bumps.* Front end has a mushy and vague feeling, similar to lack of rebound damping.

Too Much Compression, Fork
* Harsh ride, especially when bumps and ripples are first contacted by the front wheel.
* Bumps and ripples are felt directly; the initial hit is routed through the chassis instantly, with big hits bouncing the tire off the pavement.
* The bike's ride height is affected negatively; the front end rides too high in the corners; bike may want to drift wide in corners.
* Brake dive is reduced, though the chassis is upset significantly by bumps encountered during braking.

Lack Of Rebound, Shock
* The ride is plush at cruising speeds, but with increased speeds the chassis begins to wallow and weave through bumpy corners.
* Poor traction over bumps under hard acceleration; rear tire starts to chatter due to reduced wheel control.
* Excessive chassis pitch through large bumps and dips at speed; rear end rebounds too fast, upsetting chassis with pogo-stick action.

Too Much Rebound, Shock
* Harsh ride; rear suspension compliance is poor and "feel" is vague.
* Poor traction over bumps during hard acceleration due to lack of suspension compliance.
* Bike wants to run wide in corners since the rear end is packing down; this forces a nose-high chassis attitude, which slows steering.
* Rear end wants to hop and skip when the throttle is chopped during aggressive corner entries.

Lack Of Compression, Shock
* Too much rear end squat under acceleration; bike wants to steer wide exiting corners (since chassis is riding rear low/nose high).
* Hitting bumps at speed causes the rear to bottom, which upsets the chassis.
* Chassis attitude affected by large dips and G-outs; steering and control become difficult due to excessive suspension movement.

Too Much Compression, Shock
* Ride is harsh, though not quite as bad as the too-much-rebound situation; but the faster you go, the worse it gets.
* Harshness hurts rear tire traction over bumps, especially during deceleration. There's very little rear-end squat under acceleration.
* Medium to large bumps are felt directly through the chassis; when these are hit at speed, the rear end kicks up.

Adjust the corresponding adjuster for the symptom no more than two clicks at a time, do a few laps and see how the difference is.
It's trail and error basically and you need time to do it properly. A track hire scenario with a couple of other riders you get on with works best rather than trying to do it during practice on race day!

Once you get your damping sorted to level your happy with then you will find you only do the odd click here and there as a part of finer tuning to suit a different track or race conditions, ie rain!

Hope this helps.

 

[Tuscani451]

I agree with your idea that often suspension shops and on-line calculators will give a heavier spring than is ideal for the rough tracks club racers often run. I was once chastised by a suspension guru because I wanted the suspension more like a Cadillac and less like a freight train. When you think about how much energy is needed to compress a heavier spring I think I'd rather land on the side of being too soft than too hard. I am considering using a lighter weight oil when I upgrade my forks.

 

[Engine-R]

Let me add some more information about suspension setup.

A very good website therefore is Peter Verdone Designs - Home
and there under 'Springs' we can read
'The correct spring is the softest spring available, that is able to support the bike and rider under the hardest of braking/accelerating while still leaving some room for the system to travel if a bumb is encountered in this state.'

Also a high recommendation is the 'Race Tech's Motorcycle Suspension Bible' from Paul Thede (Owner of Race Tech) and Lee Parks.

 

[Kojiiro]

A good book to read is The Suspension Bible. You will really learn a lot about set up, and much more.

I have 2shocks, a K tech sprung for my weight @ 185kg/mm and an Ohlins with a 190/mm. I’ve done my best lap time on the Ohlins but the k tech definitely feels better. A side note is that I’m not sure if I done my best lap time because of the harder spring, or because of improved rider skill. I would say I still have ALOT of growth on the track. I’ve only done 16 track days in the 4 years I have been riding.

Edit: I can’t read. Engine-R already mentioned the book.

 

[Kiwi Rider]

A good book to read is The Suspension Bible. You will really learn a lot about set up, and much more.

I have 2shocks, a K tech sprung for my weight @ 185kg/mm and an Ohlins with a 190/mm. I’ve done my best lap time on the Ohlins but the k tech definitely feels better. A side note is that I’m not sure if I done my best lap time because of the harder spring, or because of improved rider skill. I would say I still have ALOT of growth on the track. I’ve only done 16 track days in the 4 years I have been riding.

Edit: I can’t read. Engine-R already mentioned the book.

Do you mean 8.5kg/mm and 9.0kg/mm?

I'm running an 8.5kg/mm K-tech spring on an Ohlins shock in my SV and it's about right for my 130lb weight. When I first got the bike it had a 9.5 in it but I felt every crack in the track and it could unsettle the bike when cranked right over.

 

[Kojiiro]

Do you mean 8.5kg/mm and 9.0kg/mm?

I'm running an 8.5kg/mm K-tech spring on an Ohlins shock in my SV and it's about right for my 130lb weight. When I first got the bike it had a 9.5 in it but I felt every crack in the track and it could unsettle the bike when cranked right over.

I’m fairly certain the vendor who sold it said 185. I will double check when I get home the data sheet he sent with the shock. The k tech shock is good.

 

[Kiwi Rider]

I’m fairly certain the vendor who sold it said 185. I will double check when I get home the data sheet he sent with the shock. The k tech shock is good.

He may have been talking lbs but even then it seems a strange number.
Yeah if I invest in a rear shock for the Ninja i will probably go with K-tech.

 

[misnblu]

Great read so how is this post not pinned or stickied to this topic? 🤷🏼‍♂️🤔🤨🤦‍♂️

Thank you @Kiwi Rider for this informational post. 🙏🏽