2018 MSF Superbikes: the importance of suspension

If you are interested in pushing the performance of your motorcycle to edge of the envelope, what is the first thing you do? Most riders would look into increasing engine power or braking capability but the single biggest impact you can make to your bike’s performance is suspension.

Suspension, for many riders, is a bit of a dark art. A real anecdote shared with the author by an experienced motorcycle tech engineer is a rider took his bike to the track and whacked the suspension settings to ‘hard’, as in the absolute maximum.

No real surprise when the bike came into the shop the next day after being high-sided. The engineer said this, “see this bike? All the settings were at maximum. There is nothing left. And you wonder why the suspension does not work?”

So, how do you make adjustments to your suspension, what do they mean to you and why should you look into upgrading suspension components on your bike? There are three main points of adjustment on a motorcycle’s suspension, front or rear.

These are spring pre-load, compression and rebound, with a fourth part often neglected by riders, static sag. Getting the balance between these suspension settings is crucial to proper bike behaviour and key to keeping it stable at speed and in corners.

But, as experience has proven, making suspension adjustments without knowing what you’re doing can oftentimes make the situation worse, instead of instilling confidence in the rider. The first rule is to only make small adjustments at a time and to keep a record of what changes were made.

In the stress and confusion of a track day or in the race pit, it is all too easy to lose track of what has been done to the bike. Get into the habit of recording all the necessary information when making suspension adjustments, including external variables such as tyre pressures, rider and bike weight.

Most riders are familiar with pre-load adjustment, usually at the rear monoshock. Using a C-spanner, a lock-ring is turned to compress or relieve the rear spring, which allows for how much weight the bike can bear for a given amount of spring travel.

For the forks, depending on the brand, adjustment is made with a spanner or a grub screw in the top of the fork. Generally adjustment is made, taking into account rider weight, and pillion, if any, with full gear, for two-thirds compression travel and a third in extension to give optimum spring performance.

Too much spring travel and the bike will drop too far when the spring is compressed, sometimes hitting the bump stop. Too little and the bike will feel very skittish, skipping over bumps and breaking traction.

The second two settings are where many riders starting chasing the rabbit down the rabbit hole – compression and rebound adjustment. Basically, compression is how fast the suspension moves under load, such as braking or acceleration, and rebound is how fast the suspension moves back to its original position.

Lastly, there is static sag, which is how much the suspension compresses under the weight of the motorcycle alone, and combined sag, which is the weight of the bike and the rider. Sag determines how much pre-load you will need and will determine the behaviour of the bike when it is ridden, with the general rule of thumb being the suspension should take up a third of its travel with the rider on board.

Those are what the terms mean, but how would you go about changing the stock suspension values? In most cases, an off-the-shelf motorcycle, with the OEM suspension and settings, are calibrated to about 75% of riders and riding capability. Also, in the interests of cutting costs, many stock suspension components have no adjustability, or very limited adjustment.

This is where after-market suspension components specialists such a K-Tech suspension come in. Specialists such as K-Tech Suspension provide an extensive list of upgrade components to suit all sorts of bikes and riding styles by varying or upgrading items such as springs and internal items.

For example, a rider who does a lot of track-days and amateur racing such as the MSF Superbikes series, will have different requirements to a rider who cruises long-distance to the border. In consultation with a trained suspension specialist, the rider can fine tune the performance of the bike’s suspension to suit his or her needs.

This can take the form of a fork cartridge kit to allow for finer compression and rebound adjustment or to move the adjustment range to a tolerance that suits the rider and the bike’s intended purpose better. For some riders, a complete suspension upgrade is recommended, replacing the fork and/or the rear shock absorber to deliver better performance.

Riders that fall outside the median for weights and heights should consider a suspension upgrade to customise the ride of the motorcycle to suit. As stated earlier, bikes are designed to cope with the ‘average’ rider and anyone falling outside the norm will need to make adjustments for a stable, more confident ride.

Racers, of course, have a different set of criteria to road riders, and then there are the fast sport riders, who need road compliance from the suspension for a certain amount of comfort but performance at high speed as well. Take the time to speak to your mechanic about your bike’s suspension settings, and spend some time fine-tuning and upgrading the suspension to your needs.

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