Suspension Setup and Troubleshooting

[Scotteq]

The first step is setting proper sag. This simply refers to how much the bike 'sags' when you sit on it. Sag is always measured from the fully extended position. Lever the wheel off the ground, measure, sit on the bike and measure again: That's "Rider Sag." "Static Sag" is how much the bike sags all by itself. Putting a zip-tie around one of the fork legs simplifies measurement and can be left in place so you can see how much suspension you are using.

Since damping can/will effect your readings, you should set sag with the damping dialed to fully soft. Be sure and write down your settings so you can return to them when you are done.

You’ll need 2 people to help you do it accurately, but the mechanics of setting sag are simple: One person levers the back of the bike off the ground on the sidestand and front wheel, while a second person measures the total available travel of the swingarm from the axle to whatever part of the bodywork/frame is convenient. It is important that you pick a spot that’s directly above the axle. I like to write an ‘X’ on a piece of masking tape to be sure I’m measuring the same thing every time. Write that number down, as it is your baseline. Then you sit on your bike in your normal riding position, ideally wearing your gear. One helper steadies the bike, while the other repeats the measurement you just made. Subtract the second number from the first, and you’ll have the amount the bike is actually sagging under your weight. Add or subtract spring tension at the shock until you get the number you are looking for. That accomplished, you would then repeat the process for the front forks. As I mentioned above, a zip tie around the swept area simplifies measurements.

For a streetbike, I've found that 40mm up front and 30mm in the rear is a good place to start. Track mavens would/should start around 30/20~25. Since it's the more important, set rider sag first, and then go back and check static sag - The bike *should* sag a little by itself: 5~10mm is good. If you have proper rider sag but no static sag, then you have to wind your springs too tight, and you should install heavier springs. More than 10mm static sag and you should think about going to a lighter spring.

If you want to be really precise, you'll factor in suspension 'stiction' as well. Stiction refers to the amount the suspension sticks because of internal friction. With the bike roughly dialed in, and you sitting in riding position, have a buddy press down on the triple, and release. Measure. Then have him lift UP on the front and allow the bike to settle again. Take the average and use that as your baseline. A 0~5mm difference is considered very good. More than 5~10mm is OK, but you might check your methodology and look for things that might be misaligned. If you're closing on 15mm of stiction or more, you have a real problem and should take your bike to a pro for a rebuild. (But you probably already knew that 'cause your bike handles like crap!!!) Repeat for the rear.

I've had my best luck setting the rear first and then doing the front.

[Scotteq]

NEAT SAG TRICK: Put your bike into a long fast sweeper on neutral throttle and relax your grip on the bars as much as you dare. The bike will likely make a movement:

If it falls into the turn: You are setup favoring initial turn in over side to side flickability. Add front preload to move to neutral.

If it stands up: You are setup favoring side to side movements over initial turn-in. Remove front preload to more to neutral.

Where you end up with that is rider preference. Note: The movement I'm describing should be slow. If the bike darts one way or the other, then you should head back to the garage and re-check what you've done.

Since doing the job properly takes a couple buddies, it makes sense to do everyone's bike at the same time.


Damping Settings

Once you have set your springs properly, then you can move on to damping. You *did* write down your settings when you set sag, right!?!?! Normally, your owner's manual will have some baseline settings, but if that's not available, you'll have to come up with your own.

I'll start with Rebound: A ballpark 'Guesstimate' is shove down on the front while holding the brake and allow the bike to spring back on it's own - It should rise back up, but make NO additional movement. If it does, add rebound. If it does not, take rebound away until it does, then add back just enough to stop the excess movement. Rear rebound: Shove down on the back of the bike, no brakes: It should take about 1 second to rise back up.

Compression settings are more open to interpretation. I like JUST enough up front to stop excess diving on the brakes. You'll have to ride to determine that - try 1 turn from full soft and play from there. You'll want to balance the front and rear, though - Bounce lightly and heavily on the bike with both brakes on and have a buddy stand off to the side watching you. Interfere with the bike's movement as little as you possibly can: Your buddy is watching that both ends of the bike rise and fall together.

VERY IMPORTANT - Suspension tuning is an iterative process, meaning that 1) as you make changes, the changes you make may require to tweak a little more, 2) As you progress as a rider, your damping requirements will change (generally stiffer the more aggressively you ride), and 3) Riding in different situations requires different settings: Most obviously one setup for the street and another for trackdays. Even then, as you improve, your trackday settings will likely change as well. What works when you're running 1:55's may not control the bike properly when you up the pace to 1:53’s.

This little fact of life means that it is very important to keep track of your suspension settings and what changes you make over time. That will ensure you can play around with different setups and still be able to return to where the bike was before should you need to. Those who may be REALLY serious would also add columns to their notebook about the specific results the changes they made gave them. That's not necessary for most riders, though. But DEFINITELY keep a little notebook - You won't remember your settings.

[Scotteq]

TOO MUCH REBOUND (REAR)

- Wheel tends to hop in turns with small bumps

- Wheel skips too much when braking on rippled pavement. Does not develop good braking power

- Poor rear traction when accelerating over small bumps or rippled pavement


Shock may 'Pack Down' - Too much damping keeps the wheel from extending enough before the next

- Suspension Gets harsh over medium or large rolling-type bumps at speed

- The first few don't feel bad, but after that the suspension gets harsh and starts jumping around

- Rear and can Pack In under acceleration, causing the bike to run wide under power

- Rear "Swims" under hard braking


TOO LITTLE REBOUND (REAR)

- Bike wallows when exiting corners or in long rolling dips in sweepers

- Bike feels soft or vague

- Rear pogo or chatter on corner exits, general loss of traction, and tire overheating

Rear Compression

TOO MUCH COMPRESSION (Rear)

- Suspension seems rigid, instead of absorbing

- Suspension is harsh over small bumps

- Wheel skips when braking hard on rippled surfaces

- Very little squat - Loss of traction/sliding

- Tire overheating

- Suspension is harsh over pavement changes

- Shock stays too rigid and doesn't use enough travel to absorb bumps

- Shock rarely or never seems to bottom out – Even on the biggest bumps

- Bike Kicks on large bumps


TOO LITTLE COMPRESSION (REAR)

- Shock bottoms out on Medium-sized bumps

- Rear squats under acceleration

- Bike doesn't want to turn upon corner entry

- Excessive Squat under power – UNDERSTEER

[Scotteq]

Front Rebound

TOO MUCH REBOUND (FRONT)

- Front end feels 'Locked Up,' Harsh Ride Quality

- Suspension packs in and fails to return – Typically after the first bump, the bike will skip over following bumps and want to tuck the front

- Bike prone to Headshake and Tankslapping upon hard acceleration



TOO LITTLE REBOUND (FRONT)

- Forks are plush, but increasing speed causes loss of control and traction

- Bike wallows and tends to RUN WIDE EXITING turns

- Front end CHATTER, loss of Traction

- Slow to recover on Aggressive Input

- Wheel KICKS BACK on large bumps


Front Compression

TOO MUCH COMPRESSION (FRONT)

- Front End tends to ride high through corners, causing the bike to steer wide

- Suspension is harsh over small bumps

- Front end Chatter on corner entry

- Bumps and ripples are felt directly

- Suspension is generally harsh, and gets worse on braking and entering turns

- Forks don't use enough suspension to properly absorb bumps

- Forks never seem to bottom out, even on large hits

- General lack of traction can cause overheating tires


TOO LITTLE COMPRESSION (FRONT)

- Front end DIVES SEVERELY

- Front feels Soft or Vague

- Bottoms out on medium-sized bumps

- *Clunk* can be heard upon bottoming

[Scotteq]

GENERAL RULES

1) Once proper spring sag has been set, and you have damping you can live with: Put the bike into a long, fast sweeper on neutral throttle and relax grip on the bars as much as you dare. If the bike stands up, decrease front spring/increase rear spring/height to bring bike to neutral. If the bike falls in, do the reverse

2) SLIGHTLY harder rear compression helps the bike to turn in faster

3) AFTER you have the bike to the point where it does nothing bad, look to balance all the damping so the ends work together. It should only take a click or two

4) If the wheel is bouncing and you cannot really feel it through the bars/bike - That's a lack of rebound. If you *can* feel it through the bars/bike, Too much compression

5) If the problem occurs from steer-in to midpoint, then change the front. Mid-point to exit, start with the rear.

6) If the bike is too high in front, it will take more effort to steer it and you will have to hold it down. Raise your forks in the triples

7) If the bike is too low in front, it will steer dramatically and try and drive off the inside of the track. It will be unstable all the way through the turn. Lower your forks in the triples.

8) If the swingarm is too flat, the bike will squat too much. The bike will try and run wide as you exit the corner. The front end will feel light and try to dance around. Add ride height in rear/lengthen shock absorber

9) If the swingarm angle is too steep, then the bike will not squat enough, and you will experience poor traction: Wheelspin on corner exits. Lower rear height/shorten shock

10) If the bike isn't acting balanced, adjust it until is does - REGARDLESS of your initial adjustments. Balance should be maintained whether you bounce lightly or with great force.

[JBKatana]

very informative...
Thanks for taking the time to write it. It was well worth the reading.

[AKATALCUL1]

Good writeup! Great trouble-shooting!

:cool

[Arkie Redneck]

Hey man, that is great I adjusted my suspension this afternoon and I wish I had this to use before I started. I think I did it right but will see after a couple days riding. Wheelies good now though.

[AcroGoober]

huumm il have to try this and set it up for my fat ass

[MWiley600RR]

Nice.

This is excellent background info for me when I'm paying $20 to the Pro Tuner to set me up.
Helps me know what kind of feedback to give, so I can get dialed in right for different tracks