Setting Up Your Dirt Bike SuspensionIf possible find out what the standard rear spring was for your bike and make sure that's what is in it now. If you've bought your bike secondhand and the rider who owned it before you was heavier or lighter than you or was particularly fast then they may have put a different spring in it which can make dirt bike suspension tuning difficult, this can be the case for the forks as well. To set the static sag on the rear shock you first need to set the preload. Back off the locking ring and then you either tighten or loosen the main ring to increase or decrease the preload on the shock. Put the bike on a stand with the rear wheel off the ground and measure from the axle nut to a point roughly above it on the bike (say, a mounting bolt for the muffler or a part on the rear subframe), now take the bike off the stand and let it stand upright. With the bike off the stand now measure the distance between the axle bolt and the point on the bike itself. Subtract that measurement from the distance measured when the bike was on the stand, there should be about 25mm of sag, if there's more than that wind up the preload or if there's less then back it off. This measurement is called static sag. Now to set the laden sag (race sag). Take note of the measurement with the bike standing upright. Now with all your riding gear on sit on the bike in the attack position (head roughly over the crossbrace, elbows up and out and feet up on the pegs), have someone hang onto the bike for you and take a measurement again. The amount of sag should be between 90mm and 110mm, again if it's more or less then adjust the preload etc. You should be able to get it set up approximately to those figures, if it's way out on either then that can indicate that it either has different springs than standard (if you bought the bike secondhand) or that you're heavier or lighter than the model used by the bike manufacturers. They base their settings on a theoretical rider who is about 5'10" tall and about 85kg. These are just rough figures, read your owners manual for the bike, the japanese manufacturers have a decent section in their manuals on dirt bike suspension. Taking some time to learn about and set up your dirt bike suspension costs nothing and can really improve your lap times. Click here for a checklist to make sure your suspension is in good condition before you fine tune it. Click here for some brief explanations of the terms used when tuning dirt bike suspension. |
