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Motorcycle suspension-mastering a black art

Suspension Set-up: The basics

Whether you are a road rider or a racer correct suspension setupis the key to fast smooth riding and consistent lap times. Toget the best out of your bike it needs to be set up for theconditions in which you will be riding. It is considerablyeasier to set the bike up for the Track as you know whatconditions will be like for the next hour or so and thus you candial in the optimum settings for the that particular situation.To what extent you change your suspension settings will dependon whether your bike will also have to cope with riding on theroad. Unlike Roads Tracks are generally smooth and grippy. So ifyou are only going to use the bike on the track you have theluxury of fitting harder springs and modifying the fork andshock internals. If you ride on the road as well as the trackyou will probably want to keep a certain comfort level andconcentrate on just optimizing the current equipment Withincorrect suspension setup, tire wear is increased and handlingsuffers, which in turn can result in rider fatigue. Lap timescan be dramatically slower and in extreme cases safety can becompromised. Hopefully the following guide will help you dial inyour suspension for faster and safer riding both on and off thetrack. Firstly you will need to check the Fork and Shock sag:this is the amount the forks and rear shock settle under load.To measure it do the following: push down on the forks a numberof times to settle them, then mark the stanchion with a felt penor put a cable tie where the dust seal is sitting. Next ask somefor help to lift on the bars so the front wheel is just off theground and measure the amount the forks have traveled down. Thisis the static sag (or unladen sag), This can be changed byadjusting the spring preload (more preload = less sag). Repeatthe same process for the rear, this time measuring the distancefrom the wheel spindle to a fixed point on the tail. Now you areready to begin setting up your suspension. The key is to do it alittle at a time and make notes as you go. For road riding startwith the wet track settings and work from there. Basic Setup:Check the following Forks sag 18-22 mm for dry track, 23-27mmfor rain. Shock sag 8-10mm for dry track, 10-14mm for rain.Check chain alignment. If not correct, bike will crab walk andsprocket wear will be increased. Proper tire balance andpressure, starting with 30psi front and 32psi rear (both dry andwet). Steering head bearings and torque specifications - if tooloose, there will be head shake at high speeds. Front-endalignment. Check wheel alignment with triple clamps. If out ofalignment, fork geometry will be incorrect and steering willsuffer. Crash damage, check for proper frame geometry. StockSuspension Tuning Limitations Manufacturers plan on designing abike that works moderately well for a large section of ridersand usages. To accomplish this as economically as possible, theyuse valving with very small venturis. These are then matched toa very basic shim stack which creates a damping curve for thegiven suspension component. At slower speeds this design canwork moderately well, but at higher speeds, when the suspensionmust react more quickly, the suspension will not flow enoughoil, and will experience hydraulic lock. With hydraulic lock,the fork and/or shock cannot dampen correctly and handlingsuffers. The solution is to re-valve the active components togain a proper damping curve. It does not matter what componentsyou have, (Ohlins, Fox, Kayaba, Showa) matching them to yourintended use and weight will vastly improve their action.Furthermore, if you can achieve the damping curve that isneeded, it does not matter what brand name is on the component.Often with stock components, when you turn the adjusters full inor out, you do not notice a difference. In part, this is due tothe fact that the manufacturer has put the damping curve in anarea outside of your ideal range. Also, because the valves havesuch small venturis, the adjuster change makes very littledifference. After re-valving, the adjusters will be brought intoplay, and when you make an adjustment, you will be able tonotice that it affects the way the way the fork or shockperforms. Another problem with stock suspension is the springsthat are used. Often they are progressive, increasing the springrate with increased compression distance. This means that thevalving is correct for only one part of the spring's travel, allother is compromise. If the factory does install a straight-ratespring, it is rarely the correct rate for the weight of therider with gear. The solution is to install a straight-ratespring that matches the valving for the combined weight of thebike, rider and gear to the type of riding intended. Remember! &bullAlways make small adjustments, more is not always better. &bullAlways keep notes of what you have done. &bull Suspension tuning isan art - be patient

About The Author Mark Thompson Is a former IT consultant from London. He nowlives in Spain and runs a number of websites Including
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