free web stats

The Motorcycle Suspension Quick Reference Guide

There’s one critical element that keeps you heading in your intended direction on your motorcycle – the suspension.

What your motorcycle’s suspension is supposed to do is pretty simple stuff. It’s meant to absorb shock from bumps and potholes in the road or ruts out in the wild, keep the tires in contact with the road surface and maintain as close as is possible the overall geometry built into the chassis of your bike while all that’s happening.

So on to some basic terms which are used to explain how a motorcycle suspension does its business.

SPRING RATE is the amount of force (or weight) necessary to deflect (or compress) a spring a given distance. This value is generally expressed as lb/in (pounds per inch). If a force of 300lbs is applied to a spring and it compresses 3 inches, that spring can be said to have a 100lb/in “spring rate.”

TRAVEL is the distance the center of a wheel can move from full extension to full compression of the suspension components.

STATIC PRELOAD is the amount a spring is compressed while it supports the chassis when the machine is at rest.

SAG is the amount (distance in mm) the front or rear suspension moves when the bike is in an unweighted state.

LOADED SAG is the amount (distance in mm) the suspension can travel as a rider sits on a bike.

COMPRESSION DAMPING refers to the speed at which a spring can be compressed when a sudden shock is applied to the suspension components.

REBOUND DAMPING refers to the speed at which a spring extends following a shock to the suspension.

RIDE HEIGHT is the distance between the rear wheel axle and a fixed point on the chassis above, generally measured at the top of the seat position.

FORK HEIGHT refers to the amount the tops of the fork legs protrude through the top yoke or triple tree clamp.

STEERING HEAD ANGLE refers to the angle to which the steering head axis deviates from vertical. This number is larger for chopper style bikes, smaller for standard setups and is measured in degrees and often referred to as “rake.”

TIRE PRESSURE can either mask or exaggerate what could be mistaken for suspension problems. If a rear tire is under-inflated you will certainly feel that the back end of your motorcycle squirms when you lean the bike hard over and then again when you apply power on the exit of a corner.

This condition is also present with too soft a spring or not enough compression damping, but an under-inflated rear tire will often mimic some of the feel characteristics of a badly set-up suspension. Before you start tinkering with your suspension setup, make sure you use an accurate tire pressure gauge to inflate (or deflate) your tires to reach the manufacturer’s recommended pressure. It’s pretty easy to find, just read the recommendation on the side of the tires.

 

An old-school Amen Savior style rear plunger frame suspension

 

 

Motocross Suspension Setup Guide

Via: MotocrossGear.com

 

Additional Reading:

  • Motorcycle Mechanics Institute,The Complete Guide to Motorcycle Mechanics, 1984 Prentice-Hall, Inc., ISBN 0-13-160549-6
  • Motorcycle Mechanics Institute,The Complete Guide to Motorcycle Mechanics, 1984, Prentice-Hall, Inc., ISBN 0-13-160549-6
  • Wilson, H. The Encyclopedia of the Motorcycle Dorling-Kindersley Limited, 1995 ISBN 0 7513 0206 6
  • Wilson, H. The Encyclopedia of the Motorcycle Dorling-Kindersley Limited, 1995 ISBN 0 7513 0206 6
  • Wilson, H. The Encyclopedia of the Motorcycle Dorling-Kindersley Limited, 1995 ISBN 0 7513 0206 6
  • Motorcycle Mechanics Institute,The Complete Guide to Motorcycle Mechanics, 1984,Prentice-Hall, Inc., ISBN 0-13-160549-6
  • Motorcycle Mechanics Institute,The Complete Guide to Motorcycle Mechanics, 1984, Prentice-Hall, Inc., ISBN 0-13-160549-6

Whether you ride a sport bike or an American cruiser, you need to make sure your insurance coverage fits your style of riding and the bike you do your riding on.

We’re here to help you find the right motorcycle insurance, whatever you ride…

Tips for buying your motorcycle insurance, coverage you need:

  • Collision to pay for damage caused to your vehicle in an accident with another vehicle or any stationary object.
  • Comprehensive to cover such things as fire, hail, wind, vandalism, hitting an animal, etc.
  • Towing / Pickup
  • Medical payment or personal injury protection to cover the medical bills resulting from an accident.
  • Uninsured or underinsured motorist to protect us when the other driver is at-fault and does not have coverage or assets out of which your bills can be paid.