One major benefit to wrenching on a motorcycle as opposed to a car is the degree of access. Maintenance intervals on a motorcycle might be shorter than on a car, but many of the tasks are arguably easier because the parts are in the open. Case in point, adjusting the throttle cable. And speaking of adjustments, properly adjusting your motorcycle suspension is just as vital for performance and safety. Plus, while tweaking a car’s suspension is often an involved, complicated process, adjusting your bike’s suspension settings is far lower on the DIY difficulty scale.
Adjusting your motorcycle suspension is critical for comfort, stability, and handling
At first glance, motorcycle suspension looks noticeably different than car suspension, at least in front. However, whether you’re talking about motorcycle forks or rear shocks/mono-shocks, they work essentially the same as conventional car shocks or coilovers. While modern systems feature electronic components and complex valving, at its most basic, bike suspension boils down to a fluid damper connected to one or more springs.
Just like car suspension, motorcycle suspension can be designed more for performance, more for comfort, or somewhere in the middle. But both kinds of suspension do the same things. Firstly, suspension prevents bumps and imperfections from disturbing the chassis and ruining the handling, Cycle World explains. It also isolates the rider/driver from those road imperfections, thus increasing comfort. Plus, it’s only through the suspension hardware, and the ride height and geometry it imparts, that your motorcycle handles at all.
Car owners often modify their suspension to ‘correct’ a perceived handling flaw or fix a rough ride. And both are valid reasons for modifying your motorcycle’s forks and shocks as well. However, properly adjusting your motorcycle suspension to fit you and your riding style often makes such mods unnecessary, MCN notes. With just a few simple adjustments, you can genuinely transform how your bike rides and handles, Motorcyclist says. And you don’t even need to visit a mechanic to do it.
You can adjust your motorcycle suspension in your garage or driveway, starting with the sag
Adjusting your bike’s suspension doesn’t demand fancy tools, and depending on the bike, can often be done without wheel stands. All you need is a screwdriver, wrench, tape measure, rear shock tool, your owner’s manual, and maybe a friend. Also, a notepad to keep track of all the changes you make.
The first thing you need to adjust is your motorcycle suspension preload. This describes how much the springs are compressed when the bike isn’t moving. Adding preload doesn’t technically make your suspension stiffer, though because it reduces free travel, it might feel that way, RevZilla explains. But more importantly, adjusting the preload on your motorcycle’s suspension changes its ride height and sag, both of which impact handling and stability.
Ideally, Motorcyclist says, you’ll adjust the preload after checking your sag:
- Put the bike on its center stand (if it has one), have a friend hold it upright, or lean it against something
- Measure the amount of exposed slider (on inverted forks, this will be on top, rather than by the axle); this is L1
- Get on the bike dressed in your regular riding gear and assume your normal riding position, then compress the front and let it rebound
- Measure the exposed slider remaining; this is L2
- Lift the front end and allow it re-settle, measuring the exposed slider remaining; this is L3
- Calculate your sag using the formula L1 – ((L2+L3)/2)
Motorcycles often have sag guidelines, which typically fall in the 30-40 mm range, Motorcyclist says. And checking your rear sag uses the same procedure. If your motorcycle suspension sags too much, add preload; and if it doesn’t sag enough, reduce the preload.
If, like me, you don’t have these guidelines on hand, look in your owner’s manual. The manufacturer often lists factory-recommended preload settings there. They’ll differ based on where you plan to ride—street, track, highway—and whether you’re riding solo or with a passenger. And depending on the bike, the manual might also list preload settings based on rider weight.
How to adjust the preload on your motorcycle suspension
Adjusting the preload on your motorcycle suspension differs from front to rear. In the rear, you adjust the preload by spinning a preload collar up (for less) or down (for more). Manufacturers often provide special tools for this purpose, but aftermarket ones are available, RevZilla says.
I actually couldn’t adjust the rear preload on my Triumph Street Triple R. Not just because I didn’t have the tool, but also because the manual says the preload is set from the factory. For now, I left the rear preload alone. However, when I go into the dealer before I winterize my motorcycle, I’ll ask about that suspension setting.
Adjusting the preload on your forks is even easier. Each fork ‘leg’ has a special adjuster on top that, on my Street Triple R, is anodized blue. Turning it right with a wrench adds preload, and turning it left removes it.
Don’t let poor compression and rebound damping dampen your ride
After you adjust the preload and recheck the sag, the next step is to check your compression and rebound damping. Know how motorcycle suspension has springs and fluid dampers? The latter ‘dampens’ the springs’ movements so your bike doesn’t bottom out and/or bounce you off when it hits a pothole. That way, the tire stays in contact with the road, maintaining traction and handling.
Compression damping controls how quickly the shock/fork, well, compresses, while rebound damping controls how quickly it extends. And, as with the preload, you can have too much or too little. Too much compression damping and your shock/fork won’t move at all when it hits something. That’s great for smooth racetracks, bad for bumpy roads. Too little, on the other hand, and your motorcycle will dive heavily under braking, or even bottom out. And incorrect rebound damping settings can lead to instability, a harsh ride, ‘chattering’ over rough sections, or even your front wheel lifting off the ground, RevZilla reports.
One way to check your motorcycle suspension’s rebound damping is the bounce test. Press down on your bike’s seat and fuel tank with it upright and see how the fork and shock react. If they re-extend very slowly, you have too much rebound damping. But if they re-extend quickly and bounce once or twice before settling, you have too little.
However, arguably the best way to check your compression and damping settings is to actually ride the bike. If your motorcycle feels too soft or ‘pops’ when going over bumps, you need to adjust the compression damping, RideApart says. And if those bumps unsettle the bike, the rebound damping needs to be adjusted.
How to adjust the compression and rebound damping on your bike’s suspension
Adjusting your motorcycle suspension’s damping settings is even easier than tweaking the preload. Depending on the model, your bike will have a screw or knob labeled ‘COMP’ or ‘COM’ and another labeled ‘REB’ or ‘TEN.’ The latter adjusts the compression damping while the latter changes the rebound damping. Why ‘TEN’? Because it’s short for ‘tension.’
Some motorcycle forks put the compression damping adjuster on one leg and the rebound damping adjuster on the other. On my Street Triple R, the latter is on top, integrated with the preload adjuster, while the former is at the bottom. It’s the opposite on my rear shocks: on my bike, the compression adjuster is on top and the rebound on the bottom.
But regardless of position, the adjustment procedure is the same: turn the screw/knob right to add damping and left to reduce it. You’ll hear a ‘click’ as you turn the screw/knob; that’s a deliberate feature to help you keep track of the turns. Hence why you’ll often read damping settings described as clicks in or clicks out. And note, the fork adjusters move independently of each other. So, whatever you do on one leg, do exactly the same on the other.
If you’re unsure if you need more or less damping, check your owner’s manual for the factory settings. Adjust everything to those settings and go for a ride, then play around with the adjusters as needed.
What can you do if your motorcycle’s shock and forks aren’t adjustable?
Not every motorcycle has adjustable suspension. For example, while the new Triumph Tiger Sport 660 has inverted forks, they’re not adjustable at all. And its rear shock only has preload adjustment.
You can upgrade your motorcycle’s suspension by installing new shocks and forks with greater adjustability. Like car shocks, bike ones need to be replaced every so often. So, if you’re going to replace it anyway, upgrading at the same time makes some sense.
Another option, at least for your forks, is to upgrade the internal components. Your forks have to be rebuilt every so often—about every 10,000-20,000 miles, Motorcyclist recommends—which involves replacing the fork oil and various seals and washers. Changing the fork oil to a different grade, though, and installing aftermarket springs can change how your forks react to road imperfections. If you have cartridge forks, you can also replace the stock cartridge—the damper—with a different unit. This isn’t ‘true’ adjustability, but it is a way to adjust how your front motorcycle suspension behaves. Note, though, that changing your springs will affect your sag.
Still, if your bike does have adjustable suspension, tweaking its settings to suit your needs isn’t terribly difficult. And while the changes might seem small, they can have a noticeable effect on your motorcycle’s handling.
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