I had an opportunity to sit down and speak with Max McAllister President of Traxxion Dynamics in Woodstock, GA.
Traxxion Dynamics was founded in 1998 as a trackside suspension business. While at the race track Max noticed that there was a lack of suspension help for racers. It was this need that planted the seed of what would become a passion for both supplying world class suspension components and also for supporting the American dreams of small businesses everywhere.
Mr. McAllister took the time to answer some questions about general suspension setup, but also how outside factors affect that setup.
WC: What effect does changing to taller or shorter tires have on motorcycle suspension?
MM: Due to the inherent change in chassis geometry, the steering characteristics of the bike change, and the anti-squat properties in the rear of the bike change. For example, a taller rear tire would flatten out the swing arm angle, and reduce the rake angle and trail. This would change turn in effort, braking characteristics, anti-squat properties, and stability… and that’s just after changing one of the two tires!
WC: Is it possible to tune the suspension to get back to the same feel as the smaller tire?
MM: It is possible to tune the chassis in conjunction with the suspension to bring the bike back closely to how it handled before the larger diameter tire. There are many other factors that could have an effect on the handling such as tire carcass stiffness, and tire profile are a couple examples. All of these would have an effect on the bike handling. Adjustments can be made for all of these conditions to give you the three cornerstones of a good handling motorcycle.
WC: What are these cornerstones?
MM: Comfort, Confidence, and control. We believe these are the keys to a great handling motorcycle. Anytime you can increase any of these it improves all three.
WC: Can you change your suspension to work with used tires?
MM: Yes that is possible, but it really doesn’t make any sense. It's better to replace the tires as any loss of grip is noticed. Sell them to someone else, who doesn’t need high levels of grip. Also, when you did put new tires on, you would have a poor setup for the new tires. In terms of racing, pretty much all forms of wheeled racing, it is all about traction… the guy who has the most traction will always prevail. Motorcycle, car, ATV, mountain bike… it doesn’t matter. If you had more traction you would go faster, more safely.
WC: How do you tell someone what a good setup feels like?
MM: A properly setup bike will be stable in a straight line, and have a smooth controlled dive under braking to weight the front tire. The motorcycle should turn into the corner smoothly, with light effort, and fall into a “neutral” position. Neutral meaning no excess pressure on either bar to hold the line in the corner. It's best to test this on a constant radius corner. Finally, when exiting the corner and opening the throttle, the bike should go where you point it without squatting and running wide out of the turn or spinning the rear and losing forward drive.
WC: Is there a magic street suspension setup for the everyday rider?
MM: Each person has a setting that will work for them. If a stock suspension is too soft or hard for a rider’s weight and stature, no adjustment you can make will work. It needs to be tailored to that rider. A good place to start researching is an internet forum dedicated to your model of bike. You have to take the information with a grain of salt sometimes but with enough research you will see a pattern of either settings that people have had success with, or that the components are so poor from the factory that they need to be replaced.
WC: What's one thing that everyone can benefit from?
MM: Proper tire pressure. Many people adjust this to compensate for a suspension short coming. Gold Wing riders were running their front tires at 40psi to prevent cupping. This prevented the cupping but compromised braking, wet weather traction, and cornering. It masked the real problem which was a poorly sprung and badly underdamped front fork. It's also better to replace worn components than to adjust around them.
WC: Can you walk through a “how to” for the regular rider to find a suspension setup that allows them to be more confident on the street?
MM: Start with deciding if you like how the bike already handles. If your bike is doing something that doesn’t make you confident, feel like you are in control, or makes you uncomfortable… start there! It’s telling you what to do.
The most basic investment with the highest return for any bike is to have it sprung to suit your weight and intended use. Once you have the springs, and have adjusted the sag of the bike, take time to check the balance of the bike. If you feel one end is noticeably softer or stiffer than the other, try and adjust a little further to achieve balance. It is very critical to have the chassis work as “one”.
Be sure to write down your current settings so you can always go back to them. Nobody wants their suspension to be worse. You have to be honest with yourself and ask when you make a change, "Can I really feel the difference?". Changes typically seem better at first because they are different, but that's not always the case. You need to really look at whether the change increases the three cornerstone items. Go back and forth between your original settings and the new setting to check.
WC: Want to add anything more?
MM: Suspension systems work on a bell curve. It’s necessary to have a system that will work well for a broad range of riders. We apply our philosophy to the components we build, but every once in a while someone comes along who needs something different or doesn't fit into that concept. That's when we go back and make changes to suit that rider’s specific preference. There really is no right or wrong with suspension, as long as it gives you comfort, confidence, and control when you ride!
Continue Reading: Modified Suspension Q&A With Traxxion Dynamics>>
How To Set Sag:
This is the first step to finding a good suspension setup. Once sag is set it allows all of the other adjustments to do what they are designed to do. Give you comfort, confidence, and control. This process works for both the front and rear of the motorcycle. It is more accurate to use metric measurements if possible. (Photos are for display purposes only)
Step 1: Get a couple friends to help you. This is not something you can do easily by yourself and you don’t want to get it wrong.
Step 2: Determine the unladen suspension measurement. To do this you need to get the wheel off of the ground and measure from the axle to a fixed point on the body or frame. A center stand works the best as it’s easy to do both the front and rear. If you don’t have a center stand you can have your friends lift the bike, or on sport bikes in particular leaning the bike onto the side stand leveraging the wheel off of the ground is effective. We will call this dimension R1 for rear unladen. Make sure to put a piece of tape or some other mark so you measure to the same spot each time. For the front you need to raise the front wheel off of the ground so the forks are completely extended. Measure from the dust seal to the bottom of the triple clamp or to the axle for an upside down fork. This measurement is F1 for front unladen.
Step 3: Now repeat this process with the rider wearing their gear. Have a friend hold the bike so the rider can put his feet on the pegs. Have another friend take the same measurements as before marking them R2 for rear laden and F2 for front laden. It helps to have the same person take the measurements to add additional accuracy to the measurement.
Step 4: Subtract R2 and F2 from R1 and F1 respectively and you have your sag. Typical street bike sag is 30-35mm and race bikes are generally set to 20-30mm. These are recommended numbers and not cast in stone. Check where your setup is at and write it down before making changes. Test every time you make a change to see if it improved the ride. Remember the three cornerstones, comfort, confidence, and control. If you find that you cannot get the sag measurement close to these settings chances are your springs or either too soft or too hard for your weight.
Step 5: Sag is set by using the preload adjusters on the front fork and shock. Refer to your individual owners manual for how to adjust your specific motorcycles settings. If your bike lacks these adjustments you would need to replace the rear shock with one that has adjustments. The front forks often times can have new internals installed to give you the proper setup.
I hope that this helps many of you get started on the right path to a better suspension setup. In the coming weeks we will look at rebound and compression damping.