Dual Sport Bike - Preload

It is important to understand the effect when adjusting preload on your dual sport bike. Changing preload only compresses the spring more or less. This does not make the spring harder or softer. It only changes the bikes balance.

It sounds confusing, I know. But unless you physically remove the spring and fit another it is pretty obvious that compressing the spring more or less cannot make it harder or softer. It only raises or lowers the portion of the bike above the corresponding wheel that the spring supports.

So by changing the preload you simply change the bikes balance which means making the bike higher at the rear and lower in the front or vice versa. This affects the bikes geometry and changing geometry has corresponding effects on handling. When the front and the rear are at the same riding height the bike is balanced.

If you add bags front or rear, carry a passenger or change only a front or rear spring to a harder one instead of both springs, or change preload on either front or rear the balance will go out. The science behind frame geometry, wheel base trail, rake, offsets, center of gravity and suspension damping etc. is very complex and needs an entire book to explain. So trust me for you out there it is only important to know a balanced bike is critical to correct handling!

Basically we get three different scenarios:

1) Front low, back high

This can be caused by

  • the forks being pulled though the triple clamps too much,
  • heavy tank bags,
  • weight too far forward,
  • too much rear preload
  • or too little front preload.

If your bike rides low at the front you will notice: over steer, headshake, and front tends to fold in on itself in ruts and when riding in sand, front very nervous and twitchy, and bike tends to fall into turns. The cure: add preload to the front forks or reduce preload at the rear shock.

2) Front high, back low

This can be caused by

  • a heavy or tall rider/passenger or heavy bags,
  • forks pushed down though the triple clamps too much,
  • too much front preload,
  • too little rear preload.

You will notice: bad fork action, front wheel tends to wash out in turns (under steer), the bikes front wheel tends to climb out of ruts, the bike is difficult to get to turn and requires more effort to get to start turning. The cure: add preload to rear shock spring or reduce preload on fork springs, pull forks up further through triple clamps.

3) Balanced

Your bike should handle fine. No adjustments needed.

Important to remember is that adventure bikes have preload adjusters to compensate for frequent load changes on the bike.

So why do adventure bikes come with preload adjusters? In order to handle the off road situations they require a relatively long suspension travel.

Dramatic Changes in Bike Balance

So why do adventure bikes come with preload adjusters? In order to handle the off road situations they require a relatively long suspension travel.

This, combined with the fact that they are the one group of bikes that are often loaded with heavy bags or carry a pillion passenger, causes dramatic changes in the bikes balance. Due to the long travel the negative effects of loading the bikes is more pronounced.

Preload adjusters are easy to use and are a quick way to compensate for day to day load changes. This in turn makes the bike safer to ride and handle better. Most dual sport bikes come with preload adjusters both front and rear. Rear shock preload adjusters are often hydraulic. They have a knob you turn to adjust the spring preload easily. Front forks on some models have a preload adjustment on the top of the fork.

Some dirt bikes also have preload adjusters. It is best though to change springs on dirt bikes (not necessarily on dual sport bikes) if the rider is heavier than 90kg. Normally you ride solo on dirt bikes and preload is only a quick fix for heavier riders. For the dirt bike to work best you need stiffer springs front and rear if you are heavier than 90kgs.

If you consider going on a long tour with bags and/or a passenger you should consider fitting progressive springs to setup your dual sport bike properly and get the best performance from your suspension.

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