Keeping my arse end on the ground

[Robert Taylor]

Braking hard on my 06 ZX6R ( suspenders re gassed and oil changed by CKT) I am finding the rear is coming up too easily.

Just a hard ride around average surfaced country back roads under brakes and the back end is just flying in the air, even yawing around sideways on a corner entry. After a while I went to practice some emergency braking to see if I could improve things but no matter what posture, tank squeezing, weight distribution etc I used... I could not get even close to the front skidding/locking. This is something I have always been able to do on other bikes and told me I was at maximum braking ability of the tyres.

I want to know if there is something that can be done to give me more braking power should I need it in an emergency. The last thing I want to do is just fly over the handle bars into a car that's pulled out in front of me. It's assuring to know that I could lock the tyre should I want to.

ZXR250, VFR400 nc30 and other 90's sports bikes definitely stop quicker than this thing.

I am guessing a lot has to do with the CG since those 90s bikes are far lower (especially NC30s with the low V4 motor). Also those bikes dive a hell of a lot more. One thing is for sure- you have to put a hell of a lot of force into braking to have the rear lifting on those bikes and that's if you're front doesn't lock first!

Maybe there are some suspension adjustment techniques that could give more available braking power before the back wheel comes into the air?

Less preload to lower the bike?

More front preload and less rear preload to tip the bike slightly up?

I have a good sag setting so I'm not keen to rip into anything without reason.

Basically what I'm trying to say is that the tyres have obviously got way more grip than I can make use of at the moment. It definitely does not stop as fast as a ZXR400 I can tell you that! (This is modern machinery- so I'm guessing it can out do a 90's sports bike with abused to fuck rear shock and forks on the brakes!)

Suspension specialists please share your knowledge!

Please remind me of the jobcard number and I will refresh myself what was done to these forks etc and then come up with a solution. Please PM me the number
There is also a possibility that the front fork oil level is slightly too high which has a similiar effect to it being too low...

[racefactory]

Guys, I solved it totally.

Found the front forks have been lowered heaps- protruding through the triple 14mm.

I put them right back up to the top... brakes HARD AS!!!

Turns in stiffer but all you need is flick the bars a little more. Braking is more important to me than a flicky, very light to turn in bike.

No wonder my preload was set right at near maximum for any improvment. Too much weight going to front end. The factory recommended settings actually make sense now. Can brake hard as with rear tracking on ground and can even lock the front tyre with weight off the bars.

[pritch]

Doncha just love a happy ending?

[schrodingers cat]

Don't have to be a smart arse mate- definitely could be me... question for you on your high horse then, how do I stop it coming up under hard braking given everything i've already mentioned?

Weight is off of the bars going into the tank, body back, hitting rear brake first.

Sure, since you ask so nicely. Lenghten your braking distance.

Because if the front tyre and brake package can generate sufficient force the load transfer creates an overtuning moment and levers the tyre off the ground.

At which point, if you're sensible you'll release some of that force and prevent the rear wheel being at the front. Strategies for releasing force are to pull harder on the front brake and cause the tyre to slip or more commonly release the brake lever a bit.

You could re-engineer your bike with a lower COG and much greater rearward bias but that has other implications.

Fiddling with the dampers will alter the timing of the chassis pitching but that won't alter the inevitable.

With your new super duper CKT front shocks it sounds like the front is working fine. Maybe too fine. Because what you said in your first post is that the front locking was how you guaged the grip of the tyre (half true - you recognise the point at which the tyre becomes oversaturated) but the way you are riding the bike puts too much emphasis on that strength.

Is that a clue? Did the problem exist before the service?

[racefactory]

Sure, since you ask so nicely. Lenghten your braking distance.

Because if the front tyre and brake package can generate sufficient force the load transfer creates an overtuning moment and levers the tyre off the ground.

At which point, if you're sensible you'll release some of that force and prevent the rear wheel being at the front. Strategies for releasing force are to pull harder on the front brake and cause the tyre to slip or more commonly release the brake lever a bit.

You could re-engineer your bike with a lower COG and much greater rearward bias but that has other implications.

Fiddling with the dampers will alter the timing of the chassis pitching but that won't alter the inevitable.

With your new super duper CKT front shocks it sounds like the front is working fine. Maybe too fine. Because what you said in your first post is that the front locking was how you guaged the grip of the tyre (half true - you recognise the point at which the tyre becomes oversaturated) but the way you are riding the bike puts too much emphasis on that strength.

Is that a clue? Did the problem exist before the service?

Use any way to put it that you want, simple fact is a skidding tyre is past it's limit of traction. If you want me to go into all the details: yes the susp had time to load the tyre, no it wasn't caused by too much force at the lever quickly... simply progressive braking till it passed what was probably just over 1g.

I said all the other older sports bikes i've ridden don't do this.

Put it this way... It was like riding a bicycle with a tall as seat, you brake and the rear wheel comes straight into the air. Lower that seat down now and it takes a massive longitudinal force to cause that. Therefore causing shorter stopping distance making more use of the tyre.

It's not about my braking, just the bikes attitude how it was set. If you could even fathom braking so hard you'd know what the difference was but unfortunately you seem to be happy playing lord of the keyboard no?

Thanks to all for sharing views... some of those things definitely helped.

[schrodingers cat]

Use any way to put it that you want, simple fact is a skidding tyre is past it's limit of traction. If you want me to go into all the details: yes the susp had time to load the tyre, no it wasn't caused by too much force at the lever quickly... simply progressive braking till it passed what was probably just over 1g.

I said all the other older sports bikes i've ridden don't do this.

Put it this way... It was like riding a bicycle with a tall as seat, you brake and the rear wheel comes straight into the air. Lower that seat down now and it takes MORE longitudinal force to cause that.

It's not about my braking, just the bikes attitude how it was set. If you could even fathom braking so hard you'd know what the difference was but unfortunately you seem to be happy playing lord of the keyboard no?

Ewwwww. Pissy two times in a row. Apply some methodology to the problem rather than asking random strangers for a band-aid.

What you're saying is you don't like the 'feel'
Was this why you got the forks played with in the first place?
Did the feeling exist prior to the service?

Comparing to earlier generation sportsbikes is apples and oranges.

Why not put different brake pads in the front? That will change the 'feel'

Anyway - signing off now. As a mighty lord of the keyboard I'm off to practiCe stoppies on the Mudbug. It is TE- AWESOME!

[racefactory]

Ewwwww. Pissy two times in a row. Apply some methodology to the problem rather than asking random strangers for a band-aid.

What you're saying is you don't like the 'feel'
Was this why you got the forks played with in the first place?
Did the feeling exist prior to the service?

Comparing to earlier generation sportsbikes is apples and oranges.

Why not put different brake pads in the front? That will change the 'feel'

Anyway - signing off now. As a mighty lord of the keyboard I'm off to practiCe stoppies on the Mudbug. It is TE- AWESOME!

Why make it so complicated ffs? When was I saying I don't like the brake feel, retard?

I just said the rear wheel is lifting into the air. Needed some suggestions. Problem solved- have a nice life.

[Robert Taylor]

Glad youve got it sorted and I guess theres a lesson in that we all come up with fixes on the basis of the info given! When in fact there was a fundamental issue ( fork position )and I guess everyone assumed it was in a regular place.
Dont worry about the negative vibes from some immediate past posts. While the guy made a couple of good points he didnt need to come across like he did.

[schrodingers cat]

Guys, I solved it totally.

Found the front forks have been lowered heaps- protruding through the triple 14mm.

Yay!

Just curious who managed to do that?
And why it took so long to spot?

[racefactory]

Glad youve got it sorted and I guess theres a lesson in that we all come up with fixes on the basis of the info given! When in fact there was a fundamental issue ( fork position )and I guess everyone assumed it was in a regular place.
Dont worry about the negative vibes from some immediate past posts. While the guy made a couple of good points he didnt need to come across like he did.

Hey Robert- for a road bike how much clearance do you think should be remaining before bottoming out? Currently with full braking on stock suspenders I'm left with just under 2cm of travel remaining which I thought was pretty good. enough to account for a bump or hole under full brakes maybe.

Also, I know preload doesn't alter the spring rate but I'm sure the bike really feels noticeable stiffer after winding it on? I thought it just moves the suspensions range of travel up and down/

[Robert Taylor]

Hey Robert- for a road bike how much clearance do you think should be remaining before bottoming out? Currently with full braking on stock suspenders I'm left with just under 2cm of travel remaining which I thought was pretty good. enough to account for a bump or hole under full brakes maybe.

Also, I know preload doesn't alter the spring rate but I'm sure the bike really feels noticeable stiffer after winding it on? I thought it just moves the suspensions range of travel up and down/

The amount of travel you have left will vary. If you ride the bike at Manfield you will use more travel as it is a braking circuit and has banked corners. If you ride on street circuits it will need the addition of a whole load of oil to increase the secondary air spring trapped compression ratio. Ordinary street riding that is not so aggressive will use rather less travel. In the wet you will use even less travel as there is less available grip so you will need a combination of lower oil level, less preload ( sometimes softer springs) and less aggressive compression damping.
Ordinarily I prefer to see 10mm of safety in case you run off line into an abrupt bump that will suck a little more travel.
Anyone that tells you ''my suspension is perfect''s talking through a hole in their head, its never perfect and can ALWAYS be better, for any given scenario.
Indeed more preload alters only spring force, not the rate. By winding on extra preload it will indeed feel firmer at the start of the stroke because you have increased spring force, but it still will act as a relatively soft spring later in the stroke.
Where springs are clearly too soft the instinct of the rider / tuner is often to keep winding in more preload, to the point where there is so much initial spring force the forks feel harsh at the top of their stroke but will still bottom out! The forks will also top out too readily and that really hurts edge grip when accelerating off turns. so then people slow the rebound down and because rebound cross talks with compression it hurts low speed compliance.
Often this is about a denial to spend money to actually do the job properly! Stronger linear wind springs in a rate suitable for rider height / weight and application will require a whole lot less preload meaning that there will actually be significantly less spring force than an overpreloaded and oversoft spring at the top of stroke! So the forks will actually be more supple and compliant in that important part of fork travel and there will be more mechanical grip because the forks will move! In the latter reaches of stroke there will be much much better brake dive control because the springs are firmer in rate and will therefore have more spring force later in their travel.
Hope this all helps.

[owner]

^^^ hahaha^^^ Har fuck I wish I understood suspension!!!
I read that all and now under stand why they call it a black art

I understood bits an pieces of it an your a ledgend for getting on here an tryin to educate the masses thanks RT

[gatch]

^^^ hahaha^^^ Har fuck I wish I understood suspension!!!
I read that all and now under stand why they call it a black art

I understood bits an pieces of it an your a ledgend for getting on here an tryin to educate the masses thanks RT

It all makes good sense. Now 2 stroke tuning is a black art..

[racefactory]

The amount of travel you have left will vary. If you ride the bike at Manfield you will use more travel as it is a braking circuit and has banked corners. If you ride on street circuits it will need the addition of a whole load of oil to increase the secondary air spring trapped compression ratio. Ordinary street riding that is not so aggressive will use rather less travel. In the wet you will use even less travel as there is less available grip so you will need a combination of lower oil level, less preload ( sometimes softer springs) and less aggressive compression damping.
Ordinarily I prefer to see 10mm of safety in case you run off line into an abrupt bump that will suck a little more travel.
Anyone that tells you ''my suspension is perfect''s talking through a hole in their head, its never perfect and can ALWAYS be better, for any given scenario.
Indeed more preload alters only spring force, not the rate. By winding on extra preload it will indeed feel firmer at the start of the stroke because you have increased spring force, but it still will act as a relatively soft spring later in the stroke.
Where springs are clearly too soft the instinct of the rider / tuner is often to keep winding in more preload, to the point where there is so much initial spring force the forks feel harsh at the top of their stroke but will still bottom out! The forks will also top out too readily and that really hurts edge grip when accelerating off turns. so then people slow the rebound down and because rebound cross talks with compression it hurts low speed compliance.
Often this is about a denial to spend money to actually do the job properly! Stronger linear wind springs in a rate suitable for rider height / weight and application will require a whole lot less preload meaning that there will actually be significantly less spring force than an overpreloaded and oversoft spring at the top of stroke! So the forks will actually be more supple and compliant in that important part of fork travel and there will be more mechanical grip because the forks will move! In the latter reaches of stroke there will be much much better brake dive control because the springs are firmer in rate and will therefore have more spring force later in their travel.
Hope this all helps.

That's really good, thanks.

[Brett]

You could just slow down Rossi

If there is something wrong with his riding style or more likely the set up of the bike causing rear instability when under braking then I think that "slowing down" is really not the focus. If I am riding on really cheap, crap, worn out tyres and my bike is slipping around everywhere, then I don't think slowing down is the ultimate solution...fixing the problem is.