Raise the forks through the
yokes to drop the front end
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Now suspension consists of those long bouncy things
at the front which hold the wheel on and the little springy thing
squeezed between the the engine and the swingarm which gets covered
in crap from the back tyre.
On any half decent sports bike you've got 8 forms
of adjustment in total - ride height, spring pre-load, rebound damping
and compression damping front and rear. 'Course, that's 12 if you
count both forks. So twiddling with any of this stuff is a trip
into mystery and adventure ..
Use a suitable spacer to
increase rear ride height
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Ride height does what it says, changes the height
the bike rides at ... which is kind of self evident but we have
to make the point just to keep you awake. The most common mod is
to speed up the steering by raising the front forks through the
yokes, so lowering the front end, and jacking up the back end either
by using a spacer between the shock top and mount or, if you've
got a really posh bike, winding up the inbuilt ride-height adjuster.
Normally the most you can reasonably go to is 10mm each end. Raising
the rear will also help ground clearance. It won't turn an old R1
into a K5 but it will help the steering turn-in a little bit better.

Alloy collar above spring screws down to increase preload
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Spring pre-load determines the amount of static
sag and the shock will either have a screw collar for adjustment
or a posh remote hydraulic twiddler. An easy way to check this is
to park the bike on its sidestand, then simply rock the bike and
watch what happens to the suspension. If it compresses noticeably
as it comes upright then time for a proper check.
Get someone to hold the bike upright and measure
the distance from the axles to a mark somewhere above on the chassis.
Then lift each end in turn and measure between the same points.
Now sit on the bike and do it again. If you're a quick rider you
want only minimal sag, perhaps 10 mm at the rear and no more than
25 mm at the front. Too much and the bike will get very unsettled
over uneven roads at high speeds.
The little screw does the rebound and
the silver nut does spring preload
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Rebound damping, adjusted by the little screws
at the top of the forks and the screw or knob on the bottom of the
rear shock. Start by backing all the screws out and then do a static
test, bouncing the bike up and down and increasing rebound until
you can feel some resistance as the springs unload. Now go for a
ride. If the front bobbles as you come off the brakes or weaves
about as you bounce out of small dips you need to increase rebound
at the front until this goes. If the back end weaves about as you
power through bends then increase rear rebound. Keep fiddling until
the bikes feels stable. Go too far and the tyres will have to help
the suspension too much as it fails to recover quickly enough from
the last bump and pumps down - then you'll start to lose grip.
Knurled knob at top adjusts
compression on rear shock
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Compression damping - probably the hardest one
to get a feel for. Adjustment is by the little screws at the bottom
of each fork leg and either a screw on the shock top or the knob
on the remote gas reservoir. Too much fork dive under braking and
a loose feel when suddenly tipping into a corner indicates insufficient
from compression damping. A slappy front end when accelerating hard
means the rear shock is compressing too much, so unloading the front
- increase rear compression. A loose feeling from the back when
powering though bends also indicates insufficient rear compression
damping. The end result is a very personal thing, as it's a compromise
between bone-jarring accuracy of line and luxomatic plushness with
'orrible vague handling.
Projecting screw on the bottom of the fork
leg adjusts compression
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Don't be afraid to experiment hugely with the suspension
settings. If you're a scaredy-cat note down your original settings
on a piece of paper and stick it on your fridge. If you've never
fiddled properly with all those little screws and spring collars
you'll be amazed how much you can change the feel of your bike.
And you can create some proper set-ups for track use - rather than
wallowing about in the slow group you will be Mr. Getoutamyway in
the fast lot! At the end of the day you can simply return your suspension
to pot-holed crap British roads settings and wallow homeward in
perfect comfort, but this time with nicely re-profiled footpegs
and end can and thoughts of rearsets for more ground clearance ....
Tie wraps on both
the fork legs and the rear shock (or O rings if you can
be bothered to fit them) show you how much suspension
travel you are using. On a given road or track outing,
if the units bottom out the suspension effectively stops
working - if you're only using 50% of the available travel
the units are probably set up too stiffly for general
road and trackday use. Reader John Higham suggests fitting
adjusters to the top nuts so you can turn them easily
and tighten up or slack off till you've got 80% / 90%
travel. When you've got that far it's time to fiddle with
damping. He sees loads of guys adjusting damping at the
track when they've got the springs set up too stiffly
and they end up overcompensating. He got his info from
the WP Suspension school ("course I have to push
that as they sponsor me...") Visit his site at
teamemmenracing
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Regular twiddling will also keep your bike handling
as best it can. All of us are guilty of getting good settings and
then forgetting them for ages. Then we ride a new bike and think
"Blimey, this is sharp". So immediately we start adjusting
our own bike and bingo ... mega sharp handling again, as we compensate
for wear and tear on springs, damping oil, etc. If your bike's a
few years old it's worth changing the fork oil and seals. If the
rear shock is showing its age it's probably best replacing with
Ohlins, WP, Penske or whatever takes your fancy rather than going
for a rebuild - many factory shocks aren't rebuildable anyway. Trouble
is, the front end will then be letting you down as standard production
forks are often built way down to a price, and valving can be suspect.
You don't necessarily need to buy new forks, but replacing the internals
with K-Tech kit can improve control and the cost of the bits you
need should not be much more than £200 plus fitting.
A word on high and low speed damping, as it all
gets a bit confused. Bang though a bloody great pothole in the road
and wham!, the suspension has to blow oil fast to allow a sudden
large amount of spring movement to absorb the shock. Basically the
shim stacks lift and allow the oil to flow through bypass holes
- this is high speed damping, which often happens when you're travelling
slowly.... Now you're belting along a good road with some cracking
dips and rises, compressing the suspension by fine degrees, the
oil flow controlled by the shims. This is low speed damping in action,
even though you're going quickly the suspension is moving relatively
slowly to absorb the rise and fall of the bike as the loading changes.
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