Sunday, May 13, 2007


I'm not going to repeat the pages and pages of information available on the net about suspension setup. Dozens of people have written complete tomes with details and explanations of the how and why. Here's a good example:

But I'm going to render an opinion about suspension that's obviously contrary to what most people think is the objective of suspension setup.

The objective is to make the suspension COMPLY with the surface of the road. COMPLIANCE is the key, the objective, the goal, nirvana.

Compliance happens when the tires follow the complete surface of the road, never leaving, always in nicely planted contact, regardless of how the road heaves, buckles, or bumps.

Perfect compliance is impossible, but improvement is relatively simple to attain.

So I'm going to start with a visualization. We've all driven empty pickup trucks. They're stiffly suspended in back so they can haul big loads, but when they're unladen, they handle like crap. The back end bounces all over every bump and it's obvious that the rear wheels aren't complying with the road surface. There is very little compliance when it's needed.

So why do so many people set up their motorcycles to be stiffly suspended? 99.9% of the time you're on your bike, you're not headed for Road Atlanta's old "Gravity Cavity" at 150 miles an hour! You're in a world where you don't have to worry about bottoming out both ends of your machine at the same time!

And so, I say "let your suspension work". You should set up your bike so the suspension actually moves. If the manufacturer gave you 4" of travel up front, then you should be using 3.9" of travel when you do a stoppie! If you got 6" of travel in back, you should be using 4" (yes, only 4) when you're under full acceleration! (Leave 2" for a passenger.) You should never "bottom out" unless you're goofy enough to do a stoppie into a chuck-hole, but for heaven's sake, use what you've got!

Suspension travel is a gift. Use it.

On the subject of ride height, pitch, static sag, and front / rear balance, tire profile and height, I leave you to the internet. It's such a subtle science and so highly personal in its acceptance and results, it's not worth going into here. As an example of how exotic this pseudo-science is, I give you any set of race results. Take two racers on similar bikes..... one does well and the other does poorly from the same stable..... Is it the bike? The rider? The setup? Is the setup actually "the bike"? Isn't the rider responsible for determining setup? Did he read the calibrations on his ass correctly for his seat-of-the-pants testing runs?

See what I mean? It's not always something you can write in stone. There are lots of facts and there are a thousand opinions on each of those facts.

So my bit of 'wisdom' for you is simply to use most of the suspension travel you're given. Go for compliance and then always be smooth. Your ass will thank me and your results should improve on both the street and the track.

No comments: