Suspension is my nemesis

If I am riding over rough & bumpy bitumen, what is the best adjustment to
make to the suspension? Harder/softer preload? harder/softer rebound
damping? combinations?
The manual is ambiguous as it only really clearly mentions adjustments
suitable for added weight to the bike (ie make everything harder!)
My bike ('07 VFR800) has stock suspension - ie front = preload only; rear =
preload & rebound damping.
I have a really nice & twisty ride where I live (central qld), but am
becoming sick of having my arms really shaking a lot & leading to being
really jerky on the throttle.
Suspension is the bike topic I know least about.

Any ideas?

 

Long travel soft suspension is good for these types of roads (buy a BMW GS).

Boxer

 

What he said ;-)

travel is really your limit here...

for our purposes the analogy of catching a brick in your hands is not
particularly accurate, but close enough to be meaningful. The force of the
brick moving through the air. a bigger brick would be a bigger bump ;-)
your hands are the suspension. Let's say that your hands are one meter off
the ground and you have to stop the brick from moving before your hands hit
the ground. if you have to catch the brick and you can move your hands a
long way, you can absorb the force very gradually. This equates roughly to
long travel low damping suspension - great for huge bumps!

if you have to catch the brick and your hands are only 10cm off the ground,
you have to absorb that same force much more abruptly. This is short travel
suspension (sports bikes). What happens now is that the ride is not very
smooth because the spring rate (resistance of your hands) needs to be
relatively high. if its not stiff, you will bottom out your suspension (and
smash your hands!).

In the ideal world, your spring rate is set (approximately) to be able to
absorb the full force of bumps you will go over before you run out of
travel. In reality, this is really hard to do because you ride over many
different types of road, with different amounts of weight on your bike. so
it's a compromise. requirements of suspension for smooth road vs bumpy road
vs dirt vs two up touring vs racing are all different....

theoretically, for your setup, the best setting for bumpy roads is to set
the preload to be less until the point where the suspension *just* bottoms
out on the worst bumps, ditto compression damping if you have it. then bump
them up a notch. wind your rebound damping down (if you have it). A wiser
way to go would maybe be a set of progressive springs for your forks, and a
new spring on the rear. with new fork oil and springs ($200-$300 if you do
it yourself) you will be amazed at the difference!

Shaun

 

Back everything off to softest settings and then try it. If you're
bottoming out (clunking at fully compressed) then up the damping a few steps
at a time. (You can increase the front's damping by changing the oil to one
that's more viscous. 5W to 10W etc)
If you're scraping or you just generally feel too low at one or both ends,
up the corresponding preload.

 

Try this site for start-up settings and some good advice if you need more
http://www.sportrider.com/bikes/146_street_bike_suspension_settings/index.html#honda

 

Yeah do that. Bump impulses are a high velocity event. Damping is
really the best way to adapt the response of your bike to what you
want, and frankly adjusting clickers does 1/4 of F.A. Revalving to
suit your weight and requirements is the way to go.
Or just deal with it!

 

Take it to a suspension tuner and get them to talk to you but before you do
that take a look at your posture and loosen up those arms.

justAL

 

The job of preload is to get spring working in the right part of it's
travel, it's not a substitute for the correct weight spring or the
right damping. The job of damping is to manage the rate at which the
spring compresses.

So... first consider your weight and that of your passenger if
applicable. If you're outside the range the bike has been built for
(and that'd probably be 60-120Kg for a VFR I'd imagine) or close to
the edges seriously think about getting a different weight spring.

If you're in the 60-75 range backing your preload off from stock is
usually a good rule of thumb on tourers (NB on a sports bike that's
about the range they're setup for - they don't expect passengers or
luggage).

Choppy suspension response on bumpy roads usually indicates one or
several of:

- too much preload (running out of travel too quick)

- too high a rate spring for the load (ie light load and stiff / pogo-
ey response)
*or*
- too soft a spring rate for the load (ie heavy load and going
straight to the end of the stroke - you'll know all about it if it's
this one ! VERY jarring)

- too much compression damping

- too little rebound damping (packing up)

Other than that read the link someone else posted, also do some
googling there's a south african mag that had a good beginners guide
and there'll be a few others around

JL

 

hard to do when he has no adjustment over compression and only rebound at
the back.

 

I thought it was too MUCH rebound that caused packing down.

 

You purposely ignored the bit about the more-viscous oil did you Richard?

 

No need to get viscious.

Theo

 

But that would change BOTH the compression and rebound damping. This may
not give the desired effect and requires specialised equipment and
knowledge.

 

So you're not only stupid you're stupid AND pedantic.
Is that the point you were trying to make?

 

You're a bastard Clem, but a funny one. Thanks for the LOL

 

Just trying to be accurate

Considering he has no compression adjustment at either end I fail to see how
"upping the damping a few steps at a time" will have any effect on bottoming
out.

"generally feeling to low?" - how does that help him if he has no concept
of suspension adjustment?

The correct advice would be to:

1. Set the rear rebound to standard (see owners manual)
2. Get someone with "some idea of suspension setup" to set the static sag
front and rear (ie preload)
3. Go from there with regards fiddling with rear rebound
4. If necessary, get front and/or rear suspension revalved/resprung.

Pedantic enough for you?

Richard

 

Oh is THAT the point you were trying to make?!!?
OK; confusing and pedantic then!
Yes; you're correct of course. The damping will only affect the front.

I have bugger all "concept of suspension adjustment" either (as proven) but
I know if the bike feels too low at one end or if it's scraping.

Not only pedantic but even helpful; what a pity you didn't post that
before.......
(Though 2. is out; he wouldn't be asking here if he knew someone else who
would help him!)

 

Anyone got any suggestions about someone in the "know"?

 

Should just offer a word of warning.

It is important, prior to making ANY modifications to a suspension set-
up, that the rider has a good idea of their aims in regard to
suspension operation. Otherwise 'jarring ride' could mean anything.
There is a distinct trade-off between 'road holding' (traction
performance) and 'ride' (comfort and isolation from rough surfaces).
This compromise becomes incredibly difficult to achieve for a
cornering situation due to the unstabilising effects of bump force
transmission into the chassis during a corner. Suggest that you get
your head around your actual aims before stuffing with anything.
Assymetrical damper response (firmer in rebound than compression) has
been around for over 30 years now and its purpose is simply to allow
an improved ride/road holding compromise. This is done because in bump
(compression) less force is transmitted to the chassis, and yet the
higher level of damping in rebound is selected to control the wheel's
oscillation to maintain good grip. Also be aware that the clickers
used for damping 'adjustment' act only at reasonably low velocity
inputs, hence modifying your damper's response to rough roads is far
more effective by revalving. As mentioned previously, springs that are
too stiff is another cause of excessive force transmission. IT IS a
TOURING bike, and likely sprung with a pillion load in mind. How much
do you weigh?
It SOUNDS like softer fork springs and prehaps a revalve COULD lead to
some improvement. Clem was on the money with his first post.
Just beware it is not a simple problem.

Also jerking the throttle due to road bumps is just a problem with
your technique. You are holding the throttle WAY too tightly.

Hope this Helps,
Chris