“Hell, it’s good enough as it is. Why should I take the chance of messing it up?”
Well, here’s a reason: it makes your bike feel nicer. Usually much nicer.
And you don’t have to be some knee-dragging god to appreciate the difference. What’s more, if you can put up a shelf you’re perfectly capable of doing it.
Ignore pub ‘experts’
If anyone tells you what the hot set-up ought to be for your bike, they’re talking out of their backside.
Unless they weigh the same as you, caress the throttle and brakes just the way you like to, and ride the same roads, they don’t know.
They might make a pretty good guess, but fine adjustments are down to you and only you. So the first thing is: trust yourself.
The basic idea
You can set up a bike very well using just three principles:
1. Get it sitting in the right place on its springs with you on board.
2. Aim for the best possible ride quality.
3. Check that (2) doesn’t compromise the bike’s ability to deal with the violent weight transfers of braking and direction-changing.
1. Set your preload
This is the hardest bit because on most bikes the rear preload adjustment is tucked away in a recess which 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 leather gloves.
Preload seems harder to understand than it really is. Bounce the back end of a bike and it’ll spring back up to a rest position somewhere between the top and bottom of its travel.
Exactly where that rest position is depends on how much preload you’ve added. Crank it up and the back of the bike will rest a little higher off the ground than before. Back off and it’ll sag lower.
The aim is to have a setting where the wheels can go up over bumps, and extend down in to hollows, without actually hitting the top or bottom of the suspension travel too hard.
Needless to say, fatties want more preload than skinnies. On most roads your preload is about right if you use up 25-30 per cent of your wheel travel, sat on the bike normally in riding gear.
You can calculate how many millimetres this is by looking up the suspension travel in your manual (usually about 130mm both ends).
Balance with your elbow against a wall and get a mate with a tape measure to see how much the bike sags from full extension, along the line of the forks, or above the rear a wheel spindle.
2. Set your ride quality (stage 1)
Big, heavy bikes with soft suspension (think Yamaha XJR1300) often manage to have lovely ride quality: they plough on ahead while the wheels whizz up and down over bumps, just like an oil tanker on a choppy sea.
Unfortunately the lighter a bike gets, the more it bobs around over bumps like a rowing boat.
Manufacturers respond by making the wheels as light as possible, and using high quality suspension, which is why a GSX-R or Blade can feel as supple and unruffled over manhole covers as a much heavier Harley.
However, you’ll notice the word ‘can’ in the last sentence: as standard, sportsbikes feel much more choppy 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 (especially the ultra-grunty 1000s) 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 each from standard, 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 squidging out of bends too much, go back to the previous setting.
(This all applies to a 75kg rider on most sportsbikes. Obviously, if your bike dives or squidges too much as standard, increase compression damping).
3. Set your ride quality (stage 2)
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 of front rebound), and if the back doesn’t pogo half way through a fast chicane or mini roundabout (rear rebound), then you can try another click.
4. Job done
Eventually you’ll end up with a bike that still keeps the lid on the violent stuff (at least for your weight and riding style), but soaks up bumps as well as possible.
And that’s the point of adjustable suspension.