motocross bike race sag setting up guide, by yours truly

local scenrio, many dirt bikers, after buying a bike, would without doing some basic setting up, like suspension, gear levers, jetting, etc have already bring the bike out for a ride, and would start to complaint on some area when the bike handling is really out of the way. so for a start, i guess with my basic knowledge of suspension, to post something up here for you.


How to do proper race sag set up for ya dirt bike?

This setting up of race sag procedure that follows will give ya a ballpark figure of a recommeded starting point for any suspension tuning. My article will guide you to the proper race sag adjustment for your weight. Fine tuning of damping adjustments will comes later. The first step toward determining proper suspension adjustment is to set the rear spring preload so the proper race sag is achieved.


1. Firstly, load the whole bike onto a bike stand, with both wheel off the ground, allowing the rear wheel to be fully extended

2. now, use a maker pen and mark somewhere vertically above the centre of the chain adjuster block as your reference point for measurement

3. use a measurement tape and take the reading, eg 615mm

4. for next measurement, unload the bike from the stand, with a fully dress up rider (with helmet, boots on, etc), standing with both feet on the peg, press down the rear fender gently and let it rebound on its own, do not bounce! Now, with reference to the measurement marking, take down this reading, eg 510mm

5. so your race sag is 615mm – 510 = 105mm

6. as a ball park figure, for most Japanese mx bike, recommendation of race sag to start off at 100mm, and for KTM, 105mm – 110mm

7. so with race sag at 105mm, you will need to increase preload by cranking on the top shock collar, when the sag with the rider on the bike read 515mm, you achieve the recommended race sag at 100mm.


With your race sag properly setup, you will be able to fine tune your damping setting from here, and by now, your bike should be handling much better than before, so go out and feel it!

for those who are interested to know more, you can join me in the "who wanna ride with me" training session here -> http://www.singaporebikes.com/forums/showthread.php?t=141037