Adjusting Suspension by Rupert Paul (Motor Cycle News Vol 56 No 24)

You can set up bike very well using just three principles: get it sitting in the right place on its springs; aim for the best ride quality; and check that the last step doesn’t compromise the bike’s ability to deal with violent weight transfers.

The hardest part is the first because on most bikes the rear preload adjustment is tucked away in a recess that ensures your knuckles will run with blood when you slip, as you surely will. So get a C-spanner that fits the adjuster collars, and wear thin gloves.

Preload seems harder to understand than it really is. Bounce the back end of a bike and it’ll spring back up to rest position somewhere between the top and bottom of its travel. Exactly where that rest position is depends on how much preload you have added. Crank it up and the back of the bike will rest a little higher off the ground than before. Back off a little and it’ll sag lower.

The aim is to have a setting where the wheels can go up over bumps and extend down into hollows without hitting the top or bottom of the suspension travel too hard. On most roads it’s about right if you use up 25- 30% of your wheel travel sitting on the bike in normal riding gear. Just balance with your elbow against a wall and get a mate to see how much see how much the bike sags from full extension, measured on something like a metre rule held against some part of the body work above a wheel spindle. Forget trying to compress your suspension fully to measure the total wheel travel; it’s a lot easier to look the figure in your handbook.

Next comes ride quality. Big, heavy bikes with soft, relatively crude suspension (think Yamaha XJR 1300) often manage to have lovely ride quality. They plough on ahead while the wheels whiz up and down over bumps, just like an oil tanker on a choppy sea.

Unfortunately, the lighter a bike is, the more it ‘bobs’ around over bumps. Manufactures respond by making wheels as light as possible and using high-quality suspension, which is why the GSX-R or ‘Blade’ can feel as supple and unruffled over bumps as a much heavier Harley. However, you’ll notice the word “can”: as standard, these and other sports bikes feel much choppier to ride. That’s because they have to brake, turn and accelerate very hard. And to control that kind of weight transfer takes much firmer damping than you’d choose for ideal ride comfort.

So all sportsbikes are a compromise between tanker-like serenity in a straight line, and composure into and out of corners. Fortunately, it’s easy to find the best balance for you: just back off the front and rear compression damping adjusters one click and go for a fast ride.

If hard braking (which tests front compression damping) and accelerating out of bends (rear) still feels nice, try another click. When it starts diving or squirming out of bends too much, go back to the previous settings. This all applies to a 75kg rider on most sportsbikes. If your bike dives or squirms too much as standard, increase compression damping.

If you manage to back off a couple of clicks of compression, you might be able to lighten the rebound as well. Try one click and, again, go for a fast ride. If the forks don’t rebound too fast after braking (a good test for front rebound), and if the back doesn’t pogo half way through a fast chicane (rear rebound), then you can try another click.

Eventually, you’ll end up with a bike that still keeps the lid on the violent stuff, but soaks up the bumps as well as possible. And that’s the point of adjustable suspension.