The most important detail of your new or used motorcycle that is commonly overlooked is proper suspension setup. You may have all the power in the world, but if your suspension is, too soft or too stiff you are not going to go any faster. Here are a few tips to get your suspension functioning properly, and improving your overall ride on the track.
1. CHECK YOUR SPRING RATES
Start by researching the spring rates for the front and rear that your motorcycle currently has. If your bike is brand new, research your owner’s manual. If you have or are buying a used motorcycle, make sure to inquire about any suspension work that has been previously done on the motorcycle. If the party you are purchasing the motorcycle from is 200lbs and you are 150 pounds, chances are the suspension is not going to work for you if the suspension has been setup for them. If you are unsure of the spring rates of your used motorcycle, you can take your suspension to your local suspension tuner and have your springs rated.
2. CHECK RACE SAG AND FREE SAG
Many riders will set the sag on their bikes and think that they are done, and the rear of the motorcycle is set for their weight. What they are not taking into consideration is the “free sag of the motorcycle. You can have your race sag set properly, but if your free sag is not in the right range, you may need to change your springs. Standard free sag should be between 20-30mm.
So, what is free sag? Free sag is the measurement taken when the shock is at full extension (on a stand with rear wheel off the ground) subtracted from the measurement of the motorcycle on the ground under it’s own weight (no rider).
To measure your free sag:
- Put your bike on the stand and make sure the shock is at full extension.
- Using a measuring tape marked with millimeters (“mm), measure the full extension of your bike. I use the center of the rear axle, and using the measuring tool, point straight up to the fender and make a mark. This measurement is your full extension measurement
- Then measure the same distance with the bike on the ground (no rider).
- Subtract your second measurement from your first. This is your free sag.
Free sag is very important in balancing the motorcycle. As I said, standard free sag should be between 20-30mm. If you have your race sag set (with your gear on) and your free sag is over 30mm, you are running a spring rate that is too stiff for your weight. If your measurement is less than 20mm free sag, this means that you have too much preload on the spring and you need a stiffer spring.
Below is the recommended starting point for race sag:
- 65cc 70-75mm
- 85cc 85-90mm
- 125cc and up 100-110mm (I prefer 105)
3. IS YOUR BIKE BALANCED?
Now that the rear is properly set up we should move to the front of the bike. I use my numbers from above to determine what spring rate I want to run in the front; I always fall back and rely on my proper rear set up. If I am able to achieve the proper rear setup with the stock spring, I will tend to leave the front the same. If I am changing to a softer or stiffer rear spring, I will make the equivalent change to the front. You want to keep the bike balanced.
If you want to get a better idea of fork travel to see if you have the right front springs, I recommend attaching an O-ring to your fork stanchion and recording your laps to see exactly how much fork travel you are using. However, do not be too quick to judge your fork if you bottom out slightly once on every lap. I have worked with many riders that think that they need a stiffer fork spring because they bottomed the fork out once or twice on a day of riding. If you make a change to a stiffer fork spring, you aree going to cheat yourself out of the initial stroke in all the little bumps.
4. NEXT STEP…THE CLICKERS
Now that you have your bike set up for your weight (and balanced) go out and ride. Do not be afraid to start playing with your compression and rebound adjusters, as this is the only way that you are going to be able to learn the differences in the feel of your motorcycle. In the end, you will become a better rider with a safer bike.