Compression damping controls how fast the suspension can compress; rebound damping controls how fast it can extend again. That is the whole of it. Everything else is knowing which one is causing the behaviour you dislike, and the reliable way to tell them apart is timing: compression problems show up as the wheel goes into a bump, rebound problems show up on the way out of it and for the second or two afterwards. Before touching either, set sag — a bike on the wrong spring rate will not respond sensibly to damping changes, and most riders who chase clicks for a season are actually riding on the wrong springs.
What each adjuster is doing inside the damper
A damper is a piston moving through oil in a sealed tube. Oil forced through small passages resists movement, and the resistance rises steeply with speed — which is why suspension feels compliant over a long undulation and harsh over a sharp ridge even with nothing changed. The adjusters vary the size of those passages.
The compression adjuster restricts oil flow in the direction the suspension takes when the wheel hits something. More compression damping keeps the bike higher in its stroke and reduces dive and squat, but it also passes more of a sharp impact through to the chassis and, at the extreme, makes the wheel skip rather than follow the surface.
The rebound adjuster restricts flow as the spring pushes the suspension back out. Too little rebound damping and the bike carries on moving after the bump: the front rises quickly and unloads, the rear pushes the bike up and out of a corner. Too much and the suspension cannot extend fast enough to follow a series of bumps, so it packs down — each successive bump starts from a lower point until the wheel is barely moving and the bike feels harsh and vague at the same time.
Packing down is the failure mode most riders misread. The symptom is a harsh, skittish ride, so the instinct is to open compression damping — but the cause is excess rebound, and opening compression makes it worse by letting the suspension compress further before the too-slow extension begins.
Higher-specification forks and shocks split compression into high-speed and low-speed circuits. Low speed is the range of shaft velocity you get from braking, acceleration and body movement; high speed is what a sharp-edged pothole produces. If your suspension has both, low speed is the one that changes how the bike behaves under braking and on turn-in, and high speed is the one that changes how it handles a bad surface. Manufacturers like Öhlins publish the adjuster counts for each of their units, and the sensible starting point is always the number of clicks listed on that unit's own data sheet rather than a figure copied from a forum.
Reading the symptom before turning anything
| What you feel | When it happens | Most likely cause | First adjustment to try |
|---|---|---|---|
| Front dives hard and runs out of travel under braking | Braking into a corner | Too little front compression damping, or too little preload | Add front compression damping, a click or two at a time |
| Front pushes back up quickly as you release the brake, bars feel light | Braking release, turn-in | Too little front rebound damping | Add front rebound |
| Ride is harsh over successive bumps and gets worse the longer they last | Broken tarmac, series of ripples | Too much rebound damping — the suspension is packing down | Reduce rebound before touching compression |
| Rear steps out or kicks up over a bump mid-corner | Mid-corner, on the throttle | Too little rear rebound damping | Add rear rebound |
| Rear feels wooden and the tyre patters over small stuff | Any surface, constant speed | Too much rear compression damping | Reduce rear compression |
| Bike wallows and takes a long time to settle after a dip | Undulating road, motorway expansion joints | Too little rebound at both ends | Add rebound, front and rear separately |
| Squats hard on the throttle and runs wide | Exiting corners | Too little rear compression damping, or rear sag too great | Check sag first, then add rear compression |
A method that produces repeatable results
- Set sag first and record it. The measurements are in our preload and sag guide. Damping adjustment on an incorrectly sprung bike produces settings that work nowhere else.
- Set tyre pressures to the manufacturer's figures. A tyre 5 psi low will disguise or invent almost any suspension symptom, and it is by far the cheapest thing to get wrong. Our tyre pressure guide covers reading the placard; a TPMS sensor takes the doubt out of it.
- Find the reference position of every adjuster. Turn each one fully clockwise — closed — counting the clicks as you go, then return it. Write down where each adjuster started, in clicks from fully closed. Do this before you change anything, because it is your route back.
- Return to the manufacturer's baseline. Your owner's manual or the shock's data sheet gives a standard setting. Start there, not from whatever the previous owner left.
- Change one adjuster at a time, two clicks at a time. One click is often below the threshold you can feel; four is enough to change several things at once and lose track of which. Two is a useful compromise.
- Ride the same stretch of road each time. Same route, same speed range, same surface, ideally the same day. A suspension change assessed on a different road tells you about the road.
- Write it down every time. Date, adjuster, clicks from closed, what changed, what you felt. Without notes you will be back where you started within a month.
- Go too far deliberately, once. Wind rebound most of the way in and ride slowly over a bumpy stretch, then most of the way out and repeat. Feeling both extremes teaches you what the adjuster does far faster than cautious two-click changes ever will. Do it at low speed on a road you know.
What damping cannot fix
Worn components come first. A fork with 40,000 km on it has degraded oil and worn bushings, and the adjusters will feel vague and unresponsive because the damping circuits are no longer doing much. If clicks stopped making a noticeable difference, the answer is usually service rather than settings — see the fork oil guide for intervals and symptoms. The same is true of a shock that has lost its gas charge: it will feel soft and uncontrolled at every setting.
Nor does damping compensate for the wrong spring. If sag is out and you correct the feel with damping, the bike will be wrong the moment the load or the surface changes, because you have used a speed-sensitive control to solve a position problem. Every suspension shop sees this: a bike arrives with both adjusters near their limits and the fix is a spring rate matched to the rider.
And it will not disguise a chassis problem. A weave that appears at speed, a wobble under braking, or a bike that will not hold a line usually traces to head bearings, wheel alignment, tyre condition or luggage placement rather than damping. Work through the vibration checks first. Suspension components that are worn or leaking are also graded defects in roadworthiness testing — the DVSA inspection manual section on wheels, tyres and suspension sets out how UK testers assess them, and it is a reasonable condition benchmark anywhere.
The line for handing it over: external adjusters are yours, internals are not. Revalving, changing shim stacks, replacing springs and anything requiring the damper to be opened is workshop work, both because a charged shock releases stored energy and because the settings have no meaning without a dyno. If your bike's rear shock has no adjusters at all — common on smaller and budget machines — the honest answer is that it is not adjustable, and the upgrade path is a replacement unit rather than a workaround.
Setting up for two-up and for luggage
Adding a pillion and panniers moves the whole bike deeper into its travel and increases the mass the dampers have to control. Preload restores the ride height; damping then usually needs a little more of both, because the same spring is now moving more weight. Manufacturers frequently publish a laden damping setting alongside the solo one, and it is worth finding yours rather than inventing it.
Record the laden settings as a named configuration in the same notebook as the solo baseline, along with the laden tyre pressures. Switching between them then takes two minutes and a torch instead of an evening of experimentation in a hotel car park. All figures here are indicative — use the values in your own owner's manual and factory service manual for your model and year.
FAQ
What is the difference between compression and rebound damping?
Compression damping controls how fast the suspension compresses when the wheel hits something. Rebound damping controls how fast it extends again afterwards. Compression problems are felt as the bump arrives, rebound problems in the second or two after it.
Which way do I turn the adjuster to add damping?
Clockwise adds damping on almost all motorcycle suspension, and fully clockwise is the closed position adjusters are counted from. Always count clicks from fully closed rather than from wherever the adjuster happens to be, so your notes mean something.
Why does my bike feel harsh over successive bumps?
Usually too much rebound damping. The suspension cannot extend quickly enough between bumps, so each one starts from a lower point and the wheel eventually stops following the surface. Reduce rebound before adding compression, which is the instinctive change and the wrong one.
Should I set sag before adjusting damping?
Yes, always. Damping controls the speed of movement, not where the bike sits. If the spring rate is wrong for your weight, no combination of clicks produces a bike that works, and any setting you find will stop working when the load changes.
My adjusters do not seem to do anything — what now?
Either the suspension is worn to the point where the damping circuits are ineffective, or a shock has lost its gas charge. Both are service items rather than settings. High-mileage forks with original oil are the most common case.
