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Bouncy front end going round corners?

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-Savage-
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Joined: 10 Jun 2005
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PostPosted: 12:14 - 12 Apr 2007    Post subject: Bouncy front end going round corners? Reply with quote
when i go roind a corner leaning in, the front end can get a bit bouncy, to the extent that im scared of binning her. i presume this is due to the setting on the forks, do they need to be harder or softer?
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willi
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PostPosted: 12:19 - 12 Apr 2007    Post subject: Reply with quote
you may need oil in them? wat sort of bike is it?
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veeeffarr
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PostPosted: 12:21 - 12 Apr 2007    Post subject: Reply with quote
What weight fork oil do you have in there?
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Diggs
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PostPosted: 12:33 - 12 Apr 2007    Post subject: Reply with quote
A proper fitting bra should do it...
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CRAZY_BIKER
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PostPosted: 12:47 - 12 Apr 2007    Post subject: Reply with quote
Just a thought , have you got to much/not enough air in the tires ?
Because it could well cause theses effects to the handling and response of you're bike.
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Marci
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PostPosted: 15:34 - 12 Apr 2007    Post subject: Reply with quote
Sounds like it needs less preload... you got adjusters?
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feef
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PostPosted: 15:44 - 12 Apr 2007    Post subject: Reply with quote
Marci wrote:
Sounds like it needs less preload... you got adjusters?


no way of knowing if it's just preload...

a 'bouncy front end' is such a generic description, it Could be caused equally by preload, rebound or compression damping settings.

not enough damping, and it'll pogo.

too much damping, and it'll bounce because it's rock hard

too little rebound damping, and it'll top out the forks witha clunk and be bouncy

too much rebound, and it can pack down, so there's no travel left and bounce

too much compession, and it won't compress enough, be too firm, and so bounce

too little compression damping and it'll dive too easily, so bounce back up


All depends on the kind of forks, the level of adjustability and what causes the bouncing, also what kind of bouncing it is.

Is it a wallowy bounce? a springy bounce? Are there any noises, knocking coming from the fork?

before identifying ANY suspension issues, tho.. make sure your tyres are in good shape.

a
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MarJay
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Joined: 15 Sep 2003
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PostPosted: 15:58 - 12 Apr 2007    Post subject: Reply with quote
feef wrote:
All depends on the kind of forks, the level of adjustability and what causes the bouncing, also what kind of bouncing it is.


I've seen people describe 'front end bouncy around corners' When their rear shock is shagged too.
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feef
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PostPosted: 16:05 - 12 Apr 2007    Post subject: Reply with quote
MarJay wrote:
feef wrote:
All depends on the kind of forks, the level of adjustability and what causes the bouncing, also what kind of bouncing it is.


I've seen people describe 'front end bouncy around corners' When their rear shock is shagged too.


quite true..

I just could't be bothered including all the Other things that can cause it, cos I'm fed up at work, and feeling lazy Very Happy

a
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FreshAL
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Joined: 04 Jul 2005
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PostPosted: 16:48 - 12 Apr 2007    Post subject: Reply with quote
I was complaining about front end wobble until I did some advanced training.

Turns out I was dealing with corners all wrong. I now sit slightly further back in the seat, and apply more positive throttle through the bend.

Front end feels so much more planted and secure it's amazing.

How old is the bike & how many miles has it done?
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MarJay
But it's British!



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PostPosted: 17:05 - 12 Apr 2007    Post subject: Reply with quote
FreshAL wrote:
I was complaining about front end wobble until I did some advanced training.

Turns out I was dealing with corners all wrong. I now sit slightly further back in the seat, and apply more positive throttle through the bend.

Front end feels so much more planted and secure it's amazing.

How old is the bike & how many miles has it done?


Weight over the front, but not sitting at the front of the seat, and mimimum amount of throttle should be a bit more than "Maintenance throttle".

Makes a hell of a difference! Smile
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-Savage-
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PostPosted: 12:19 - 13 Apr 2007    Post subject: Reply with quote
wow what a load of responses while i was away!

bikes a 99 cbr600 standard forks, dont have any idea what oil is in them, probably what was put in in the factory. its done about 27.5k miles.

im going to take it to the garage and check tyre pressures.

the bounce is spnogey/springy. theres no noise and the forks dont stop moving, they just sort of bounce lol
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feef
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Joined: 11 Feb 2002
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PostPosted: 12:20 - 13 Apr 2007    Post subject: Reply with quote
SavageKymco wrote:
wow what a load of responses while i was away!

bikes a 99 cbr600 standard forks, dont have any idea what oil is in them, probably what was put in in the factory. its done about 27.5k miles.

im going to take it to the garage and check tyre pressures.

the bounce is spnogey/springy. theres no noise and the forks dont stop moving, they just sort of bounce lol


after 27k miles I'd look at flushing and replacing the fork oil.. maybe even checking the rear shock.

a
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FreshAL
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PostPosted: 12:39 - 13 Apr 2007    Post subject: Reply with quote
feef wrote:
after 27k miles I'd look at flushing and replacing the fork oil.. maybe even checking the rear shock.

a


Is it worth increasing the pre-load (& damping if poss.) on the rear?

I still don't completely understand suspension, so this might be a completely rubbish idea.
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feef
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PostPosted: 12:53 - 13 Apr 2007    Post subject: Reply with quote
FreshAL wrote:
feef wrote:
after 27k miles I'd look at flushing and replacing the fork oil.. maybe even checking the rear shock.

a


Is it worth increasing the pre-load (& damping if poss.) on the rear?

I still don't completely understand suspension, so this might be a completely rubbish idea.


preload will stiffen the spring, and make the suspension harder. That won't necessarily fix the bounciness, it might just change HOW it bouncies (rather than wallowing/boingy, it may become hard and harsh)

Also, if the rear is harder, then any upward force on the rear wheel will cause a downward force on the front forks, pivoting about the center of gravity.

There's no real way to 'tune' out the symptoms or effects of poor fork oil, or a knackered rear shock.

best to either ride around it carefully, being aware of the limitations, until it becomes unrideable, or just get it fixed.

Suspension, steering and brakes are the 3 things I don't allow to be less than 100%. I can handle an engine that's down on power, but I still want to be able to stop and go round corners safely.

a
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MarJay
But it's British!



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PostPosted: 13:59 - 13 Apr 2007    Post subject: Reply with quote
feef wrote:

preload will stiffen the spring, and make the suspension harder. That won't necessarily fix the bounciness, it might just change HOW it bouncies (rather than wallowing/boingy, it may become hard and harsh)


Technically it doesn't stiffen the spring, it just increases the amount of weight/force it takes to make the spring start to move. Once its moving the stiffness remains the same whether on max or min preload.

But, for all intents and purposes... Wink
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feef
Energiser Bunny



Joined: 11 Feb 2002
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PostPosted: 14:19 - 13 Apr 2007    Post subject: Reply with quote
MarJay wrote:
feef wrote:

preload will stiffen the spring, and make the suspension harder. That won't necessarily fix the bounciness, it might just change HOW it bouncies (rather than wallowing/boingy, it may become hard and harsh)


Technically it doesn't stiffen the spring, it just increases the amount of weight/force it takes to make the spring start to move. Once its moving the stiffness remains the same whether on max or min preload.

But, for all intents and purposes... Wink


Ohh.. pedantic Very Happy

I was trying to keep it simple for someone that obviously doens't know the technical detail of spring-rates..

The force required to compress a metal coil spring increases (in general) linearly with it's compression. Therefore, by compressing the spring with a preload adjuster, you ARE making a stiffer spring, but also making one with less travel.

Razz

a
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FreshAL
Sir Crashalot



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PostPosted: 14:28 - 13 Apr 2007    Post subject: Reply with quote
feef wrote:
MarJay wrote:

But, for all intents and purposes... Wink


Ohh.. pedantic Very Happy

I was trying to keep it simple for someone that obviously doens't know the technical detail of spring-rates..

The force required to compress a metal coil spring increases (in general) linearly with it's compression. Therefore, by compressing the spring with a preload adjuster, you ARE making a stiffer spring, but also making one with less travel.

Razz

a


Keep it coming, I'm learning here... Laughing
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Pete.
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PostPosted: 16:39 - 13 Apr 2007    Post subject: Reply with quote
Best thing to do is have the forks apart clean all the gunge and old watery-oil out fit new seals and re-fill with fresh oil.

Then start thinking about making adjustments.
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feef
Energiser Bunny



Joined: 11 Feb 2002
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PostPosted: 17:18 - 13 Apr 2007    Post subject: Reply with quote
This is a good place for info on suspension and how it works..

also has pages with recommended setups for various bikes.

https://www.sportrider.com/tech/suspension/

a
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