Suspension Question

cbcanada

cbcanada

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Okay so I changed a few suspension settings on a bike I had picked up last summer. I should have done the following one at a time but did them all same time

1) I set front forks to stock compression and rebound
2) I set rear shock to stock compression and rebound
3) I increased rear preload for less sag and a higher ride height

So this is what I noticed right away when I got on the bike this morning.

-wow I can tell I am sitting higher!!
-less sag when I sit
-the bike is super easy to slalom. I can give the slightest counter steer input and dip the bike side to side
-the steering is almost too easy and I will use the term "loose"
-I think that loose feel makes the bike feel unstable in turns... It is no longer feels solid like "lean the bike and ride it through the turn like its on a rails" ... This is more evident in slower city turning conditions. On the highway it's not as noticeable.

my guess is I put too much preload in the back and changed the rake too much .. What do you think?

Or is it something else? But If it is the rear preload.. Is there anything I can do aside from decreasing the preload? I like the height and sag right now


"If i was educated, I'd be a damn fool"
 
cbcanada said:
Okay so I changed a few suspension settings on a bike I had picked up last summer. I should have done the following one at a time but did them all same time

1) I set front forks to stock compression and rebound
2) I set rear shock to stock compression and rebound
3) I increased rear preload for less sag and a higher ride height

So this is what I noticed right away when I got on the bike this morning.

-wow I can tell I am sitting higher!!
-less sag when I sit
-the bike is super easy to slalom. I can give the slightest counter steer input and dip the bike side to side
-the steering is almost too easy and I will use the term "loose"
-I think that loose feel makes the bike feel unstable in turns... It is no longer feels solid like "lean the bike and ride it through the turn like its on a rails" ... This is more evident in slower city turning conditions. On the highway it's not as noticeable.

my guess is I put too much preload in the back and changed the rake too much .. What do you think?

Or is it something else? But If it is the rear preload.. Is there anything I can do aside from decreasing the preload? I like the height and sag right now
Click to expand...

I'm inclined to agree: the rear sitting higher has steepened the rake a bit, decreasing the trail and making the front end twitchier. Good theory, anyway.

Suggestions/thoughts:
- increase front compression damping to reduce the rate at which the front initially compresses entering a corner
- dial back the shock preload a bit and/or increase fork preload
- if fork preload isn't adjustable, consider upgrading the fork springs to a higher spring rate (RaceTech might be able to help here...)
- lowering links for the rear, if possible?
- play with tire pressures a bit
 
The only way to get the solution you're asking for is to raise the forks by some amount. Fork extension caps may be required.

The easiest way is to dial back the preload, of course.
 
Don't listen to this and DO listen to Wingboy and set your sag properly.
Blackfin said:
I'm inclined to agree: the rear sitting higher has steepened the rake a bit, decreasing the trail and making the front end twitchier. Good theory, anyway.

Suggestions/thoughts:
- increase front compression damping to reduce the rate at which the front initially compresses entering a corner
- dial back the shock preload a bit and/or increase fork preload
- if fork preload isn't adjustable, consider upgrading the fork springs to a higher spring rate (RaceTech might be able to help here...)
- lowering links for the rear, if possible?
- play with tire pressures a bit
Click to expand...
 
What you have experienced is a taste of how everything affects everything else.

First you have to get the bike in the correct range of suspension travel front and rear. (Set the preloads to achieve the correct rider-aboard sag at both ends, this has to be done by the numbers)

Then you have to get the ride height correct so that the swingarm down-angle is correct and the steering geometry is correct. Steepening or raking-out the steering geometry will affect turn-in and changing the swingarm pivot height will affect what happens when exiting corners under power. Changing either front or rear ride height will have some effect on BOTH of these. Ideally you want neutral steering so that once you have set a certain lean angle, it should feel like you could take your hands off the bars and the bike would carry on at the same lean angle - not wanting to stand up and make you have to force the bike to continue turning, not wanting to fall in and be unstable. On a bike meant for pavement, the rear should not squat under acceleration because that will make it both lose traction at the rear (spin the tire) and run wide on corner exit, this requires the swingarm down-angle to be in a certain range (generally near 11 - 12 degrees with the suspension completely unloaded). On a dirt bike, you might want the tire to spin ...

Then you have to get the spring rates correct so that you are not running out of travel, either in cornering or braking.

The clickers (damping adjustments) are the first things anyone wants to fiddle with and they're the last things that actually need adjusting. Normally if the damping is way out of whack, internal modifications are needed to fix it. The clickers only affect low-speed damping (some high-end suspensions allow them to have some effect on mid-speed damping).

If you jump into the middle of this without dealing with the first things first, and the higher priority items need work, you will have to do it again after you backtrack and fix the higher priority matter.

First geometry, then spring rates, then damping.

Changing to a different brand/type/construction/model of tire has a way of buggering this up. Ask anyone in racing ...
 
By the way, it's inadvisable to give SPECIFIC recommendations without knowing make, model, year.

A good many bikes over the years have had designed-in "features" that really turn out to be "bugs" and need specific things to be done to fix them before you can really tune them properly.
 
Step one is Saggggggggggg, set it properly.
cbcanada said:
I came across that site.. Was going to read up On it

so the rear end has to come down or As twisted k said the front end has to come up. So I cannot achieve this by increasing front preload?


"If i was educated, I'd be a damn fool"
Click to expand...
 
Brian P said:
By the way, it's inadvisable to give SPECIFIC recommendations without knowing make, model, year.

A good many bikes over the years have had designed-in "features" that really turn out to be "bugs" and need specific things to be done to fix them before you can really tune them properly.
Click to expand...

2008 hypermotard 1100

What you said about neutral steering and feeling like you can take your hands off, I agree was like that before I messed about :-)

Ok is anyone in Durham AND knows what are doing AND want to help me set up? :-)

From what I read I need two people to do the sag bit right


"If i was educated, I'd be a damn fool"
 
To be clear, I also think that sag is important to set correctly. It just sounded like you read about it and decided that you were gonna go ahead and dial in excessive preload anyway
 
Another thing to consider is that really good riders can ride around bad suspension settings especially at high speed.
 
Is this for your Hypermotard?If it is,then you definitely need to get the sag set so that the bike isn't unbalanced anymore.Forget the damping adjustments if it has the stock sachs shock and marzocchi.The adjustments are just bling.Even with the "s" model suspension,the Hyper is a heavy streetbike with a high mass center that is easily upset when pushed hard.It's a great bike tho.Had an 09 "s" model for a few years.Also check the steering head bearings for notching and slop.Hypers are frequently abused by owners that think they are wheelie kings and land the front really hard.
 
Blackfin said:
I'm inclined to agree: the rear sitting higher has steepened the rake a bit, decreasing the trail and making the front end twitchier. Good theory, anyway.

Suggestions/thoughts:
- increase front compression damping to reduce the rate at which the front initially compresses entering a corner
- dial back the shock preload a bit and/or increase fork preload
- if fork preload isn't adjustable, consider upgrading the fork springs to a higher spring rate (RaceTech might be able to help here...)
- lowering links for the rear, if possible?
- play with tire pressures a bit
Click to expand...


or,

1. Buy a monkey
2. Blindfold it
3. Make a wall chart of suspension settings
4. train monkey to throw darts at the chart.


There is only one spring preload setting for any rider's weight, the OP is just guessing with random spring preload.

Not all bikes will have the proper suspensions for heavier riders, so not all suspensions are actually fully adjustable, they are only adjustable within a weight range.

And before I get flamed by illiterate morons, I'll reference this video by a engineer at Ohlins.

[video=youtube;FjGgq1z9zbo]https://www.youtube.com/watch?v=FjGgq1z9zbo[/video]
 
CafeRay said:
Not all bikes will have the proper suspensions for heavier riders, so not all suspensions are actually fully adjustable, they are only adjustable within a weight range.
Click to expand...
This is kind of correct, some suspensions are fully adjustable just the spring rate is wrong for the rider according to their weight. That is why you first set your sag, if you are too heavy or light for your stock springs to properly set the sag then you start thinking about changing the springs.

After all it is a street bike so having a proper sag should be more than adequate without any other adjustments.

I know very little about suspension compared to other racers but this is just basic stuff.
 
Last edited:
Watch the video.

If a rider is beyond the weight range of the factory suspension, it's not adjustable.

This is a problem in small bikes, they spring them for small riders or riders in markets that typically have smaller people (South Asia), they don't usually spring the bikes for heavier North American customers.
But, even if one updates the springs (shock and forks), the level of rebound and compression dampening may not be able to cope with the spring rate and force, so the compression could be ok, but then you pogo on bumps, or the fork dives too fast on braking. But this is really only critical on track. Most small bikes don't even adjust anything on forks.

To much preload, the rear will bounce and this means no rubber touching the road. To little, the bike will bottom out and effectively have no suspension, and again could bounce on bumps or even acceleration. Braking with no suspension left is dangerous.

The sag cannot exceed 1/3 of the total travel.

There are shops around the GTA that do this and know what they are doing, and it's far better money spent than some slipon, LED lights or tinted windscreen.

For gawd sake, do not install lowering links. They should be illegal.
 
Or spend $60 - $80 and go see John at Accelerated Technologies or Fawaz at Speedworx and get them to set it with you. They will explain what they are doing & why, and will also tell you if any of your components need upgrading to set it up right for your weight and riding style.
 
Tldr
caferay said:
watch the video.

If a rider is beyond the weight range of the factory suspension, it's not adjustable.

This is a problem in small bikes, they spring them for small riders or riders in markets that typically have smaller people (south asia), they don't usually spring the bikes for heavier north american customers.
But, even if one updates the springs (shock and forks), the level of rebound and compression dampening may not be able to cope with the spring rate and force, so the compression could be ok, but then you pogo on bumps, or the fork dives too fast on braking. But this is really only critical on track. Most small bikes don't even adjust anything on forks.

To much preload, the rear will bounce and this means no rubber touching the road. To little, the bike will bottom out and effectively have no suspension, and again could bounce on bumps or even acceleration. Braking with no suspension left is dangerous.

The sag cannot exceed 1/3 of the total travel.

There are shops around the gta that do this and know what they are doing, and it's far better money spent than some slipon, led lights or tinted windscreen.

For gawd sake, do not install lowering links. They should be illegal.
Click to expand...
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