suspension question - what and why

[pencil shavings]

Ive been thinking about suspension and how it affects the handling of a bike.

take a gsxr 600 vs a sv650. from looking online they both have a smilar weight, but due to the gsxr having better spec suspension parts it handles better. So if you put the same quality gear on the SV - front end swap and a proper shock made for the bike, i get the impression that the SV would still be out handled by the gsxr.

why is this? is it do with sprung/unsprung weight? or other factors? would changing both wheels and forks would make the unsprung weight about the same, making them handle about the same?

what would be needed to be done to the SV to make it handle as well as a modern ish 600? or is it just impossible (within reason) if it is impossible, why?

This is all hypothetical, im not trying to do anything to my bike, just get a better understanding of what it is that helps me go around corners :)

[plowsie]

The SV is/was a budget bike.

There is a hoard of things you can do to improve things. After Hayabusa rear shock mod, my bike felt much smoother once I had correct settings with it.

[ThEGr33k]

By putting the same spec equipment on you should be able to make the SV handle very similar.

The other factors that dont help are steering head angle. The Rake... Its 25* on the SV and 23.5* on the Gixxer 750. Now you can make the SV very similar if not the same by raising the rear and dropping the triples a little. This will speed up the steering a LOT.

The only thing you cant really do much about with the SV is the weight distripution. The Gixxer has a lot of its weight (its fat engine) low down which makes it feel lighter. To be honest I dont think this will make much odds when you are riding though.

Finally when you get the suspension setting right for you the bike will feel fantastic, especially if you do the above.

Cheers.

[Mr Speirs]

Wouldn't other things like frame flexibility, weight distribution, aerodynamics also contribute to handling.

[ThEGr33k]

Wouldn't other things like frame flexibility, weight distribution, aerodynamics also contribute to handling.


Yea but to be honest not enough for it to really matter on the road. On a track then aye, probably.

[pencil shavings]

so taking suspension gear from one bike and putting it on a similar but budget bike, would make it handle more or less the same?

Im quite surprised by this, I thought the weight distribution would have had a greater impact on the handling, also the rigidity of the frame etc.

interesting!

[ThEGr33k]

To be honest the difference in frame rigidity is going to be minimal. Not so different as someone like us would notice. Also Ive never read a review that said the SV's frame was anything but great.

As to weight distribution if anything the SV should benefit from having the weight up high as it will help it fall into corners! :cool:

There are two downfalls on the SV, Lack of engine tuning so not too powerful and lack of decent equipment. Sort those and the SV is a very capable bike! :D Only thing is its cheaper to just get an already sorted bike... but probably not as fun!

[pencil shavings]

cool :)

While I would like to sort the SV im not planning on doing it, i was just wondering if it was really as simple as swaping bits! I know that the front end swap etc improve it, but i wasnt sure if it would be an improvement, or being it up to par with the donar bike!

[lukemillar]

By putting the same spec equipment on you should be able to make the SV handle very similar.

See, I would disagree. I think suspension is designed around a whole number of things - the amount of power the engine is putting through the rear wheel, swingarm angle, suspension linkages and (as you say) rake and trail, weight distribution, frame design etc. Given enough time, you could mod any suspension component to fit the SV i.e at the extreme end of the scale, shoe-horning some SBK forks onto an RS125, is not going to make it handle like a superbike!

Handle better? probably - just not the same

[punyXpress]

Wouldn't other things like frame flexibility, weight distribution, aerodynamics also contribute to handling.

Starting to worry about that new yellow bike of yours already, Britney ?

( I'm only jealous ) <-- Envy Green

[Zen Beetle]

Correct me if I'm wrong but I suspect that being a 90 degree V twin would make the SV overall length longer than the gsxr and hence not as flickable.

[ThEGr33k]

See, I would disagree. I think suspension is designed around a whole number of things - the amount of power the engine is putting through the rear wheel, swingarm angle, suspension linkages and (as you say) rake and trail, weight distribution, frame design etc. Given enough time, you could mod any suspension component to fit the SV i.e at the extreme end of the scale, shoe-horning some SBK forks onto an RS125, is not going to make it handle like a superbike!

Handle better? probably - just not the same

Well kinda. Im working with properly sprung suspension in mind. Thats all it really takes. The stock dampening should be close enough to not matter a great deal. You are right it wouldn't be a straight forward job but it should be doable. N' I think done properly the two bikes wont be a million miles away. Even the SS600's arnt as good at handling as they could be... The 675 seems to be the closest to a track monster stock as they come. Of course im going off of reviews there... So I cant say.

Correct me if I'm wrong but I suspect that being a 90 degree V twin would make the SV overall length longer than the gsxr and hence not as flickable.

1420mm on the SV vs 1400mm on the GSXR, I dont think it will be an issue.

[Bibio]

ok my view, having done a gixer swap front and rear, all i can say is its miles better than stock.. with the original front end i always felt that my teeth were getting rattled out and the original shokky felt horrid and squashy and was forever throwing me out the seat. and also the breaks on the SV are not the best.. i have never regretted doing the swap even though it was expensive.

as to it handling like a GSXR.. simple answer ... NO

and the SV650 K8 is almost exactly the same dry weight as a GSXR1000 k8.

[ThEGr33k]

Have you got the rear jacked up and front lowered though? That will make a MASSIVE difference.

[lukemillar]

Well kinda. Im working with properly sprung suspension in mind. Thats all it really takes. The stock dampening should be close enough to not matter a great deal. You are right it wouldn't be a straight forward job but it should be doable. N' I think done properly the two bikes wont be a million miles away. Even the SS600's arnt as good at handling as they could be... The 675 seems to be the closest to a track monster stock as they come. Of course im going off of reviews there... So I cant say.

I found my 06 R6 better out the crate for the track than the 675 and both of them better than the k7 GXSR-600! 675 is quite a different bike though to the 600's, it has similar geomtery to a 250GP bike -trail is around 89mm.

[ThEGr33k]

I found my 06 R6 better out the crate for the track than the 675 and both of them better than the k7 GXSR-600! 675 is quite a different bike though to the 600's, it has similar geomtery to a 250GP bike -trail is around 89mm.

Aye it is pretty extreme :rolleyes:

[Domas]

What is exactly wrong with SV (pointy) original rear shock? Is it the same problem as with forks? Not much low speed compression damping and too much high speed damping?

[ThEGr33k]

What is exactly wrong with SV (pointy) original rear shock? Is it the same problem as with forks? Not much low speed compression damping and too much high speed damping?

Cheap, doesn't handle the road as well as a more expensive option. The difference between a good after market and any stocker is massive tbh. My Penske is AMAZING on the falco... Wouldn't dare go back. :rolleyes:

[ophic]

As to weight distribution if anything the SV should benefit from having the weight up high as it will help it fall into corners! :cool:
Er... no. Think inertia rather than gravity.

[ThEGr33k]

Er... no. Think inertia rather than gravity.

Well then thats wheels and discs.

Though im still fairly confident having more weight up top makes a difference, I can tell the difference between a full and empty tank.

[Domas]

Cheap, doesn't handle the road as well as a more expensive option. The difference between a good after market and any stocker is massive tbh. My Penske is AMAZING on the falco... Wouldn't dare go back. :rolleyes:

Ok, good to know. And shocks from other bikes like ninja and gsxr? Are they better/worse than aftermarket shocks made for SV? Are they usable on road? I suppose shocks from supersport bikes should be a bit on a stiff side, no?

[the_lone_wolf]

Well then thats wheels and discs.

not only wheels, inertia is a mass's tendency to remain stationary resisting motion (from the word inert) - having a large mass higher up, making the centre of mass higher where it has further to travel when the bike gets leant over means it will not turn as quickly as a bike with a lower centre of mass, all other things being equal

as for putting GSXR suspension on an SV and them handling the same, not likely, the suspension on a GSXR has been designed for the GSXR, same with all the modern supersports - these days the manufacturers have to make the bikes handle to the limits of affordable tech to be competitive in the 600/1000 market. the suspension will be of better quality, and likely have a wider range of adjustable settings, so you'll find something that you like, and that's better than the stock SV, but a good aftermarket shock designed for the SV and it's frame geometry, rake, trail, COM and myriad of other variables will be better still

[Alpinestarhero]

Well then thats wheels and discs.

Though im still fairly confident having more weight up top makes a difference, I can tell the difference between a full and empty tank.

+1. Upon an empty tank, my handling gets sort of worse (less planted feeling). Also, if my topbox is light, or I dont have it on the bike at all, the bike dosnt drop into turns as easily. It seems to me having saome weight up top helps. Sure, it'll make it hard to flick over to the toher side...but thats what muscles are for

I'm going to order a new hagon rear shock today or tomorrow, since my current item is the OEM shock...10 years old, +36,000 miles. I don't beleive I need to change the fork springs (maybe the oil, it'll be a bit old by now) as I am quite light and don't really load up the front end

Should I expect to feel a differance...?

[Domas]

If you do get Hagon shock, please write your impressions here, so I don't miss it :) Seems like Hagon shock is one of the cheapest aftermarket shocks around, so it's an interesting alternative.

[yorkie_chris]

What is exactly wrong with SV (pointy) original rear shock? Is it the same problem as with forks? Not much low speed compression damping and too much high speed damping?

It's naff. It's an emulsion type shock, which means gas and oil are free to flop around however they want in a froth. A proper shock keeps gas and oil seperate, and has valving which cost more than 4p to make, so actually keeps the wheel under control.

Well then thats wheels and discs.

Though im still fairly confident having more weight up top makes a difference, I can tell the difference between a full and empty tank.

So you're saying a GSX1100EFE or some other monster drops into corners better than some razor sharp GP bike? :-P

It might drop in, but for a bike to feel like it handles well it must be easy to stop it dropping when you need to! For that you need a low moment of inertia about the contact patch. That moment of inertia is a function of how much the thing weighs, and how high it is from the ground.



Get some gixxer forks and shock, and throw £500 at them, and it will handle better than a new GSXR/YZF/C*R/ZXxR because it will be set up for you rather than some rough guess by the factory.

Ride height yadda yadda, all this can be changed.

I would guess that the CoG of an SV will be lower than the CoG of an IL4, half the cylinder barrells and heads are a lot lower to the ground, and there are only half as many.

[the_lone_wolf]

+1. Upon an empty tank, my handling gets sort of worse (less planted feeling).
which do you want? handling or planted? if it's feeling skittish it sounds more like the bike is undersprung for your weight, a heavier bike will feel more planted simply because there's more inertial mass that needs to move to respond to bumps in the road, but a heavier bike will require far more effort to flick around the corners, which isn't the definition of handling

the trick is to get a lighter bike with suspension suited to the weight of the bike + rider, then you'll have a planted and flickable bike, my KTM is an example, light as a feather but feels incredibly planted and stable on all surfaces because of the top shelf suspension adjusted to my weight...

[yorkie_chris]

Ok, good to know. And shocks from other bikes like ninja and gsxr? Are they better/worse than aftermarket shocks made for SV? Are they usable on road? I suppose shocks from supersport bikes should be a bit on a stiff side, no?

No. To take an example the GSXR 600 SRAD shock is much softer. 750 is a little harder (iirc) but longer and works well.
They will not behave as well as a shock built for SV and importantly built for the rider. But they are 1/10th the price.

If you do get Hagon shock, please write your impressions here, so I don't miss it :) Seems like Hagon shock is one of the cheapest aftermarket shocks around, so it's an interesting alternative.

I would not bother with a hagon. They are not much different from stock, still an emulsion type shock, though they may be better set up (higher spring rate, thicker oil perhaps).

Given some cash to blow I would take a SRAD 750 shock, send it to maxton or PDQ and get them to spring and valve it for me.
Total cost about £280 and this will work, for all intents and purposes, as well as ohlins etc.

[ThEGr33k]

Get Penske two way adjuster... £600. Well worth it :D

With a decent shock set up right you'll be able to feel the grip and feel when its searching for it. Lumps in the road wont throw you out of the seat and the bike will be more "planted", mine actually feels better leant over now than sat up. ha.

[Alpinestarhero]

which do you want? handling or planted? if it's feeling skittish it sounds more like the bike is undersprung for your weight, a heavier bike will feel more planted simply because there's more inertial mass that needs to move to respond to bumps in the road, but a heavier bike will require far more effort to flick around the corners, which isn't the definition of handling

the trick is to get a lighter bike with suspension suited to the weight of the bike + rider, then you'll have a planted and flickable bike, my KTM is an example, light as a feather but feels incredibly planted and stable on all surfaces because of the top shelf suspension adjusted to my weight...

I tell you what I dont want; a bike that feels like its understeering alot...

[the_lone_wolf]

I tell you what I dont want; a bike that feels like its understeering alot...
understeering into or out of corners?

[ThEGr33k]

Both id guess ha ha.

I guess you are getting understeering atm Alpine?

Suspension. First thing is check sag. 35mm front and back is about right on the road for the SV. Suppose thats all you can do on the SV... :(

What tyre's you running? Check the pressure! Under pressure and it can go wide. :(

[the_lone_wolf]

Both id guess ha ha.

well considering they have completely different causes if he has both then he's got two problems...

[ThEGr33k]

well considering they have completely different causes if he has both then he's got two problems...


Aye... Or more :-?

[Alpinestarhero]

Both id guess ha ha.

I guess you are getting understeering atm Alpine?

Suspension. First thing is check sag. 35mm front and back is about right on the road for the SV. Suppose thats all you can do on the SV... :(

What tyre's you running? Check the pressure! Under pressure and it can go wide. :(

Since saturday the bike has been great - I think i may have had an issue with mis-aligned wheels. Specialy after I got hit by a car sort of side-ish on the other week. I check my tyre pressures often; they are spot on. I don't really like the BT021's fitted, i much prefered the MEZ6's I had before.

TLW - its understeer mid-corner...I expect im quite a part of it aswell.

Hmm, I cant really describe the ill-feeling i have with my handling, i just often have an odd feeling.

[the_lone_wolf]

TLW - its understeer mid-corner...I expect im quite a part of it aswell. tricky then, most problems will happen during the brake and turn in or when you accelerate out of the corner

if it's when you get on the throttle to come out of the corner then your shock isn't damping the compression enough to prevent the back squatting, increasing the wheelbase and causing it to run wide

if it's mid corner on a neutral throttle then it's unlikely to be a suspension problem, could well be an alignment thing, although that would surely manifest itself as understeer in one direction and oversteer in the other?

[punyXpress]

[quote=ThEGr33k;1853885]Get Penske two way adjuster... £600. Well worth it :D

On a bike worth not much more than a grand, like mine ?? :confused:

[ThEGr33k]

Since saturday the bike has been great - I think i may have had an issue with mis-aligned wheels. Specialy after I got hit by a car sort of side-ish on the other week. I check my tyre pressures often; they are spot on. I don't really like the BT021's fitted, i much prefered the MEZ6's I had before.

TLW - its understeer mid-corner...I expect im quite a part of it aswell.

Hmm, I cant really describe the ill-feeling i have with my handling, i just often have an odd feeling.


Quite possably tires? They sound like they are more touring tire than sport. I recomend. PP2ct front PR2ct back. Great wear out of the back and great grip out of the front. Thats what ill be using next (currently PR2ct back PP front).

Other than that its hard to say whats wrong without more feed back. Med corner is usually due to grip id say... Maybe not enough sag?


http://www.apriliaforum.com/forums/showpost.php?p=1948881&postcount=1 Thats all about suspension setup. Its universal. :)

A way to check bent frame/wheel alignment might be to steer left, right, left, right in a straight line (bit like F1 cars do to keep tyre's warm). If it steers both ways evenly with no bias then I think your safe. It does take some force to bend bikes.

[ThEGr33k]

Get Penske two way adjuster... £600. Well worth it :D

On a bike worth not much more than a grand, like mine ?? :confused:


Maybe. The great thing about penske is that they alter the damping, spring and mountings for you if you get another bike. So its not like you cant change bikes and use it. Though its worth asking about doing that. :rolleyes:

[zunkus]

Ohlins do a rear shock specifically for the SV with a remote reservour. It simply transformed the bike. I am so glad I did this mod, totally transformed the bike making it feel more plush, responsive and predictable. The front Matris cartridge emulator and spring mod also did it's part. I've ridden gixxers and blades and they're so flickable and light feeling but I'm totally hooked with my SV's character in how it does things which makes it more challenging and satisfying to ride well. That's me of course. The satisfaction that I did make a good bike better has something to do with it I guess.

[lukemillar]

Can someone explain to me what "planted" means? People always say "I put a new rear shock on and now the bike feels more planted". I don't get it? Fewer slides? Less wobbling? A lot of these problems are more to do with rider input than the suspension not being good enough yet there is a certain placebo effect that chucking 600-700 quid at your bike (GSXR front end, rear shock etc.) WILL make it better ;)

Most people could benefit from setting their bikes up for their weight to ensure that the suspenders they have are working in the optimum zone before swapping out forks and shocks. You'll also learn a lot more that way.

[ThEGr33k]

Can someone explain to me what "planted" means?

I suppose for me it would mean that there is less negative feedback. Like my new shock vs old, getting on the power now feels better than not, makes the bike work better with power on. Before it would have wollowed and moved around and woud feel horrid.

So I suppose its a bike feeling better.

[lukemillar]

I suppose for me it would mean that there is less negative feedback. Like my new shock vs old, getting on the power now feels better than not, makes the bike work better with power on. Before it would have wollowed and moved around and woud feel horrid.

So I suppose its a bike feeling better.

Your case is different, because your old shock was actually shot so upgrading was necessary and replacement OE shocks are stupid money!

[ThEGr33k]

Your case is different, because your old shock was actually shot so upgrading was necessary and replacement OE shocks are stupid money!


Well... it was kinda because the OE shock on the falco is not far off as bad as the SV :( Aprilia screwed up on that front.

I suppose any upgrade/improvement in cornering might come under the more "planted" thing. :cool:

[zunkus]

Most people could benefit from setting their bikes up for their weight to ensure that the suspenders they have are working in the optimum zone before swapping out forks and shocks. You'll also learn a lot more that way.

But you'd have to have suspenders that can be adjusted, I don't think that adjusting preload alone on OEM would solve all problems. Having a good quality shock which can be adjusted would though.

[Alpinestarhero]

tricky then, most problems will happen during the brake and turn in or when you accelerate out of the corner

if it's when you get on the throttle to come out of the corner then your shock isn't damping the compression enough to prevent the back squatting, increasing the wheelbase and causing it to run wide

if it's mid corner on a neutral throttle then it's unlikely to be a suspension problem, could well be an alignment thing, although that would surely manifest itself as understeer in one direction and oversteer in the other?

Since having my new chain and sprockets, and hence my wheel alignment re-done, the handling has got alot better. However, i do get the feeling of what you describe in your second point; the rear "squating down" and the bike feels loooong. I'll have to have a more carefull think about whats happening and then post on here. The bike does feel better when maria is on the back...

[Domas]

Are all normal telescopic forks with damper rods and all USD forks with cartridges? Or it's not related?

[yorkie_chris]

Not related, there are normal ones with cartridges. But I'm not sure if there have been USDs with damper rods.

[ThEGr33k]

Since having my new chain and sprockets, and hence my wheel alignment re-done, the handling has got alot better. However, i do get the feeling of what you describe in your second point; the rear "squating down" and the bike feels loooong. I'll have to have a more carefull think about whats happening and then post on here. The bike does feel better when maria is on the back...


I suggest checking sag if thats the case! You know how? :D

[zunkus]

I suggest checking sag if thats the case! You know how? :D

+1

I had the same feeling. Bike felt better with wife on board then I adjusted sag and happy with or without her, if I may quote U2 :)

[ThEGr33k]

The problem you have alpine is that the back inst compressing enough when you get on the power, this causes the front to push as weight isnt getting shifted backwards, so the front starts to slide.

Cheers. ;)

+1

I had the same feeling. Bike felt better with wife on board then I adjusted sag and happy with or without her, if I may quote U2 :)


No you cant! :p

[lukemillar]

But you'd have to have suspenders that can be adjusted, I don't think that adjusting preload alone on OEM would solve all problems. Having a good quality shock which can be adjusted would though.

Adjustment doesn't mean much! Most people (i.e not racers) will adjust their suspension once and then leave it and of the minority that do, most will only touch the preload!

[ThEGr33k]

Adjustment doesn't mean much! Most people (i.e not racers) will adjust their suspension once and then leave it and of the minority that do, most will only touch the preload!


Your right. I have a friend who seems scared to even touch preload! LOL im constantly trying to find the perfect settings. Once you know what each adjustment does to the handling then you can uaully dial out and negative feeling. :)

[lukemillar]

Your right. I have a friend who seems scared to even touch preload! LOL im constantly trying to find the perfect settings. Once you know what each adjustment does to the handling then you can uaully dial out and negative feeling. :)


Oh and as I ps. on this thread, i'm not aiming my comments at anyone inparticular (zunkus, greek etc.) These are just my observations for a number of riders. :)

[lukemillar]

The problem you have alpine is that the back inst compressing enough when you get on the power, this causes the front to push as weight isnt getting shifted backwards, so the front starts to slide.


Is that correct? My understanding is the opposite happens - it's the suspension compressing too much on the corner exit under accelaration that cause you to run wide at the corner exit.

For the front to push/slide under accelaration, the rear shock would have to be solid and give no movement whatsoever!

[the_lone_wolf]

Is that correct?

It's complete tosh mate:smt043


As you said it's the rear shock compressing too far too quickly is what can cause the bike to run wide while exiting a corner on the power, because the rear shock compressing increases the wheelbase and decreases steering head angle, two things that slow the steering and make the bike more resistant to turning

Greek, go look up some info on tuning suspension, cause you're coming out all backwards here, seriously:eek:

[ThEGr33k]

I think you must not see where im coming from, what ive put isnt wrong if you dont take it too liturally...

Your supposed to get some movement when you get on the power, if you dont then you have too much compression (preload effects it by causing the shock to rebound too quick, this causes a similar problem) on and get traction issues (due to the rear wheel not being able to move around and "dig in") and a harsh as hell ride as you'll feel every bump. As i just mentioned the rear has to move a little to find grip. For this you have to reduce the compression/preload.

Because you cant adjust either dampening on the SV you can only alter the way it rides with preload. Reducing preload makes for a less harsh ride and more traction due to the slow return to ride height while not allowing the back to squat enough to effect the front negetively.

Although it doesnt say so on many "suspension guides" its my experience that if you have too much preload on the back it pushes the front wheel too much, my guess is its because you have too much weight is over the front pushing the front tyre, you do need some weight moving back.

Im not saying go mental so when he gets on the power the bike bottoms out on the back I would be talking out of my ar$e if I told him to do that...

cheers.


For the front to push/slide under accelaration, the rear shock would have to be solid and give no movement whatsoever!

Or very little movement, too little perhapse?

[the_lone_wolf]

**facepalm**

[ThEGr33k]

**facepalm**


How much experience do you have with it? Try putting your rear compression up high enough for the rear to not move when coming out of corners or turn up the preload so its harsh and you get a similar effect. Then let me know how it feels out of corners. Im only telling you from EXP.

[the_lone_wolf]

How much experience do you have with it?

i set up the KTM myself to suit road and then track riding, preload and comp/rebound on the forks, preload, rebound and hi/lo compression damping on the shock, i never felt the need to set compression and preload to max as that's retarded...

what you're talking about is setting the preload and damping so high it completely ****s up the whole dymanic of the bike, when what you should be looking at is getting the suspension feeling close to right, or simply back to stock, and ironing out the problems you experience from there instead of screwing up the bike completely and then proclaiming the setting you screwed up was causing a relatively minor issue that would have been resolved with some minor damping tweaking

in a linear spring rate shock/forks you cannot alter the dynamic behaviour of the suspension by changing the preload, you might think the ride feels "a bit harsher" or "softer" but the reason you don't see recommendations of adjusting the preload to cure problems caused by incorrectly set damping or incorrect spring rate "in most guides" is because it's complete nonsense...:|

[lukemillar]

I think you must not see where im coming from, what ive put isnt wrong if you dont take it too liturally...

Your supposed to get some movement when you get on the power, if you dont then you have too much compression (preload effects it by causing the shock to rebound too quick, this causes a similar problem) on and get traction issues (due to the rear wheel not being able to move around and "dig in") and a harsh as hell ride as you'll feel every bump. As i just mentioned the rear has to move a little to find grip. For this you have to reduce the compression/preload.

Because you cant adjust either dampening on the SV you can only alter the way it rides with preload. Reducing preload makes for a less harsh ride and more traction due to the slow return to ride height while not allowing the back to squat enough to effect the front negetively.

Although it doesnt say so on many "suspension guides" its my experience that if you have too much preload on the back it pushes the front wheel too much, my guess is its because you have too much weight is over the front pushing the front tyre, you do need some weight moving back.

Im not saying go mental so when he gets on the power the bike bottoms out on the back I would be talking out of my ar$e if I told him to do that...

cheers.



Or very little movement, too little perhapse?

When I mean no movement - I mean like a solid bar and even then I'm pretty sure even with that, you would get enough weight transfer that the front is pretty light and therefore irrelevant.

[ThEGr33k]

No your right, I wouldnt ever purposly screw up my bikes handling. It happened due to me raising the rear. This caused the rear to be over dampened and over preloaded as it was carrying a little less weight. It caused the front to feel like it was pushing out of corners. I set the sag and ran off the compression dampening and the front being pushed sensation went.

Your right, altering preload doesnt effect spring rate. I've just done some reading "Preload is the force that has to be overcome before the spring moves at all" (http://books.google.co.uk/books?id=l2Zizg8I8p8C&pg=PA58&lpg=PA58&dq=compression+effects+on+spring+rate+motorbikes&source=bl&ots=Orb4mlhmyB&sig=t0ZRjYBuCaw2G8IrbJvcnasyg8o&hl=en&ei=cN3bSa71FdnMjAec75HVCA&sa=X&oi=book_result&ct=result&resnum=3#PPA59,M1) you should read that, for an old book there is some damn fine knowledge!) which means too much preload = similar effect to having too much compression.

what you should be looking at is getting the suspension feeling close to right, or simply back to stock, and ironing out the problems you experience from there instead of screwing up the bike completely and then proclaiming the setting you screwed up was causing a relatively minor issue that would have been resolved with some minor damping tweaking


Exactly Alpine needs to do the one thing he can do, that is check sag. Get front and rear to abot 35mm and test it then. There is nothing else he can do so there we are.


in a linear spring rate shock/forks you cannot alter the dynamic behaviour of the suspension by changing the preload, you might think the ride feels "a bit harsher" or "softer" but the reason you don't see recommendations of adjusting the preload to cure problems caused by incorrectly set damping or incorrect spring rate "in most guides" is because it's complete nonsense...:|

I honestly think Pre-load is never mentioned as a potential problem in most suspension guides because Pre-load should be set to start with, its the first thing you should do with any suspsention setup, so can effectivly be written off as a problem.

Anyhow, Ill leave it at that. Arguing doesnt help.

[21QUEST]

I haven't been too thourough :rolleyes: in reading all of that has been posted but Arghhh!!! my head hurts hehe

One thing we should try and remember is, when it comes to suspension , sometimes there are no 'definites' .

What you feel can be more important that what might actually be happening.

Can raising the bike make it easier to get the bike on it's side ...yes
Can increasing pre-load make the ride feel harsher/springs harder ...yes

Anyhoos back to the point(re Alpinstars) currently been discussed, could well be the front is shooting up too fast...no? ;) . Perhaps the front is riding too high with less petrol or less weight. perhaps the rear is indeed compressing too fast under acceleration.

One thing that perhaps Alpinestars could have been asked(apologies if already asked) was, "has it always done that?". What possible reason would bring about what he now feels if nothing has been changed on the bike....that's a question we might want to answer ;)

Lukemillar, I agree that a lot of fraffing around with suspension is done by owners when the problem is more to do with them.

Here is a sweet example. I've just stuck on some SV650 forks with racetech emulators/springs. Ride height at front is 2mm lower than standard but forks appear to be riding high. Checked sag and came out at 40mm rider sag(bear in mind the SV apparently has 130mm of fork travel)....although I'm sure some folks would think that sag figure too high number.

Now, IMO the above sag numbers make it even more puzzling, that it feels like it's riding high in front. Both high speed and low speed damping feel pretty sweet....to a point ;)

Question is, "what could be causing it to feel that way?" :) . I'm no expert but I think I know why.

As an aside once I had the Gixer forks set up the settings didn't change much even going from Summer to Winter. I think I went 1/4 on the Re-bound and that was it.

Oh and sometimes, it would appear folks forget that, bouncy bits are actually supposed to move 'up and done' . A lot of folks seem to think stiff suspension with dropped front and high end means great setup.



Ben

[21QUEST]

Another question. Why does too much preload give the feeling of harsh ride/not too good a connection between tyre and road?


Ben

[ThEGr33k]

Damn it feels bad keeping replying to this... Bah Oh well. :p

Everything you said Quest sounds right. Indeed the same setup can feel very different to different people.

Did you change the spring rate? If the spring rate is a bit hard (as mine was on the front before I changed them out) it felt like the front was riding high. But tbh if you dont care dont worry. You could though always lower the triples. See how that feels. One thing ive learnt in my setups is that testing is always worth it :)

IMO hard suspension is bad. Feels wrong. Get the right spring rate and your laughing :D


Your right, altering preload doesnt effect spring rate. I've just done some reading "Preload is the force that has to be overcome before the spring moves at all" (http://books.google.co.uk/books?id=l2Zizg8I8p8C&pg=PA58&lpg=PA58&dq=compression+effects+on+spring+rate+motorbikes&source=bl&ots=Orb4mlhmyB&sig=t0ZRjYBuCaw2G8IrbJvcnasyg8o&hl=en&ei=cN3bSa71FdnMjAec75HVCA&sa=X&oi=book_result&ct=result&resnum=3#PPA59,M1)


Another question. Why does too much preload give the feeling of harsh ride/not too good a connection between tyre and road?


Ben

Thats the best explanation I could find. I think it means if you have too much preload the travel the preload has compressed effectivley counts as spent travel. So you have a 0.9kgmm spring and you have 10mm too little sag (I.E. meant to have 35mm sag and have only 25mm sag) that 9Kg that is compressed has to be over come before the shock actually compresses any further. Sounds like a valid idea and does explain why jacking up the preload does make for a harsh ride.

[lukemillar]

Lukemillar,..........................


Just Luke ;)

[Domas]

Interesting read here :)

Got Q about springs. On RaceTech site they indicate that stock pointy springs have a rate of 0.712 kg/mm. And for road riding and 65kg rider weight they recommend 0.728 kg/mm. However their softest spring goes at 0.8 kg/mm.


I'm planning to install their cartridge emulators. Should I stay with stock spring, since it's so close to the recommended, or go with 0.8? Are their springs any better apart from spring rate? I would save some cash if I would stay with stock and get me a gsxr shock also.

What do you think guys? Don't want to run into any mentioned 'front too high' problems :/

[lukemillar]

Interesting read here :)

Got Q about springs. On RaceTech site they indicate that stock pointy springs have a rate of 0.712 kg/mm. And for road riding and 65kg rider weight they recommend 0.728 kg/mm. However their softest spring goes at 0.8 kg/mm.


I'm planning to install their cartridge emulators. Should I stay with stock spring, since it's so close to the recommended, or go with 0.8? Are their springs any better apart from spring rate? I would save some cash if I would stay with stock and get me a gsxr shock also.

What do you think guys? Don't want to run into any mentioned 'front too high' problems :/

Stick with the stock springs. They are close enough! Spring rate is what is important - not the name on the side :) Most people swap out their springs because a 65kg rider is fairly unsual - especially in Britain ;) unless of course they are female.

As for the "too high" feeling I couldn't really comment on Ben's setup. However, if you stick with the stock springs and cut the spacers in the forks down by the same amount that you are adding by installing the emulators then everything should remain the same albeit with better compression damping.

[the_lone_wolf]

i give up:rolleyes:

[lukemillar]

i give up:rolleyes:

On me? or Greek Boy?

[ThEGr33k]

Who cares...

[Domas]

Thanks Luke. I will do just that. And I also thought that springs can be easily changed later if I will find it too soft.

[lukemillar]

Thanks Luke. I will do just that. And I also thought that springs can be easily changed later if I will find it too soft.

Yep. To install the emulators you have to remove the forks, but a spring swap can be done with them in situe.

[Domas]

Any suggestions where to buy the emulators? Tried writing to PDQ but didn't get any response yet. Is it worth it to order them from the states or are there any other options in UK?

[flymo]

Any suggestions where to buy the emulators? Tried writing to PDQ but didn't get any response yet. Is it worth it to order them from the states or are there any other options in UK?

Phone up PDQ with a credit card in your hand, you'll get pretty fast response then :rolleyes:

[flymo]

Some very interesting views on what suspension does on this thread, some fairly accurate and some pie in the sky.

Adjusting preload simply puts the spring at its correct 'starting position' in terms of how much it compresses at standstill. If you are lucky, the spring is suitable for your own weight and the weight of the bike such that it compresses a given amount when you hop on board. If it doesnt fall within a suitable limit then you probably dont have the right springs for the job.

Adjusting preload to compensate for a lack of damping adjustment is nothing more than a compromise on a suspension unit that just does not have the type of adjustment necessary.

A bike can run wide for a wide variety of reasons, suspension is one of them obviously but dont forget speed (yeah really!), incorrect lean angle, crap tyres, wrong tyre pressures, unsprung weight, target fixation, road surface, wind speed etc etc.

Essentially the potential for suspension to influence a run wide is down to grip or lack of it. A good quality suspension setup provides the ability for it to be setup to an optimal level for the conditions you throw at it, if you can keep the tyres in good contact with the ground you'll have the grip to give you confidence in a corner.

The laws of physics still apply though so you will eventually land on your **** if you are going too fast for a corner.

[lukemillar]

Any suggestions where to buy the emulators? Tried writing to PDQ but didn't get any response yet. Is it worth it to order them from the states or are there any other options in UK?

I think PDQ are the only importers in the UK. I bought mine direct from racetech in the US, but my sister was living in NY at the time so I had them sent there. She just repackaged them up and sent them on to me.

[punyXpress]

[quote=flymo;1856722]Some very interesting views on what suspension does on this thread, some fairly accurate and some pie in the sky.

As you say, Flymo.
I know f'all about the subject, but it worries me that some of the suggestions appear to even me as rather dubious, if not downright dangerous. :confused:

[ThEGr33k]

As you say, Flymo.
I know f'all about the subject, but it worries me that some of the suggestions appear to even me as rather dubious, if not downright dangerous. :confused:

Which ones :-?

Only suggestion ive given is set-up SAG.

[lukemillar]

Which ones :-?

Only suggestion ive given is set-up SAG.

I don't think anything dangerous has been suggested. Even setting damping settings to max or min isn't dangerous, but will allow you to get a better understanding of the effects these things have.

People always say suspension is a dark art, but how are you suppose to learn anything if you don't try things out? In this day and age, people just pay some suspension guy to 'sort' their bike but you don't learn anything from it and even then, what feels good for your suspension guy, may feel horrible for you.

The are some general rules though worth noting. As Greek says, first off setup up your sag. There are a load of tutorials avaliable on the web to help you do this. The tech section on sport rider is a good resource:

http://www.sportrider.com/tech/index.html

Secondly, if you change something - note down the value BEFORE you change it. That way, you can always go back to where you were if you don't like it.

Lastly, change ONE thing at a time otherwise you'll have no idea how the changes you make will affect the ride.

You don't have to be riding at 100% of your ability to feel the difference, so take it easy, warm your tyres and ride over the same course so you can feel the difference at the same points on the road.

[yorkie_chris]

Even setting damping settings to max or min isn't dangerous, but will allow you to get a better understanding of the effects these things have.

People always say suspension is a dark art, but how are you suppose to learn anything if you don't try things out? In this day and age, people just pay some suspension guy to 'sort' their bike but you don't learn anything from it and even then, what feels good for your suspension guy, may feel horrible for you.

+1

[Luckypants]

Anyhoos back to the point(re Alpinstars) currently been discussed, could well be the front is shooting up too fast...no?

Was my first though to, since that was the problem with the VFR forks. Too little rebound damping made the bike run wide mid-corner as they recovered from braking and powering out of the bend tended to tighten the line again.

New oil in standard SV forks might help here?

I am in total agreement with getting sag set correctly on all bikes....

[yorkie_chris]

Oil thickness affects rebound, there isn't much you can do to give the stock ones decent amounts of compression damping without turning them solid over bumps.

What springs have you ASH?

[Domas]

I've read somewhere here in site that fork oil can vary in viscosity even if they all state for example 10W. Is this true? Or maybe the difference isn't so big to really matter?

Anyway weighting 65kg, with stock springs and emulators, i'm thinking to put 10W. As I understand it would affect only rebound. So is 10W good enough for rough road riding?

[yorkie_chris]

Yes it's true.

No, with emulators you have some effect on compression damping too, so the oil is pretty important. Ask the people who make your emulators what oil.

[flymo]

I went with 20W (was tricky to get hold of as I remember) oil on my race bike as recommended on the RaceTech suspension calculator. It feels totally rock hard at standstill compared to a stock SV but perfect when under hard load on a race track.

[flymo]

anybody got access to one of these http://www.racetech.com/page.aspx?id=37&menuid=96

This would give the information we really need to setup properly.

[yorkie_chris]

anybody got access to one of these http://www.racetech.com/page.aspx?id=37&menuid=96

This would give the information we really need to setup properly.

Very very cool technology. I want one!

[ThEGr33k]

Nice. I want!!! I want!!! :p

[flymo]

Please visit http://www.justgiving.com/flymos_racetech_bits

to raise money for my new RaceTech tools :-)

[lukemillar]

I went with 20W (was tricky to get hold of as I remember) oil on my race bike as recommended on the RaceTech suspension calculator. It feels totally rock hard at standstill compared to a stock SV but perfect when under hard load on a race track.

I used 20W too. :)

Domas: I think Racetech recommend 20W, but check with them first. If you search through the archives for emulators by a user called BlueSV650S (i think) then he did a lot of playing around with emulators and weights of oil as he couldn't get them to work how everyone else was raving. I think in the end he used 20wt or a mix of 15wt and 20wt, but if you search, you'll find the whole story.

[ThEGr33k]

I use 5W... (On the Aprilia! Dont do this on SV!) But then my front end was setup for someone who weighs 18 Stone :-?

Had 1.05kgmm springs, I put in 8.5Nmm (0.88KGmm) springs in and 5W oil. I think 5W is about right, but I can tell that the holes for dampening adjustment are tiny because just 5* of turn on one makes a VERY noticeable difference! Madness. But it seems to be there now so happy days! :D

Not I just got to find something else to play with... hmmm 125+bhp here I come :p

[lukemillar]

I use 5W... But then my front end was setup for someone who weighs 18 Stone :-?

Had 1.05kgmm springs, I put in 8.5Nmm (0.88KGmm) springs in and 5W oil. I think 5W is about right, but I can tell that the holes for dampening adjustment are tiny because just 5* of turn on one makes a VERY noticeable difference! Madness. But it seems to be there now so happy days! :D

Not I just got to find something else to play with... hmmm 125+bhp here I come :p

Just for the reocord -Different Bike - completely different setup! This guy/girl is talking about emulators and a pointy SV. 5W would pretty much remove all compression damping properties in this setup and is NOT advisable! :)

[Domas]

I used 20W too. :)

Domas: I think Racetech recommend 20W, but check with them first. If you search through the archives for emulators by a user called BlueSV650S (i think) then he did a lot of playing around with emulators and weights of oil as he couldn't get them to work how everyone else was raving. I think in the end he used 20wt or a mix of 15wt and 20wt, but if you search, you'll find the whole story.

Thanks for tip. I found the user. It's Blue_SV650S. For some strange reason he is not in members list or I missed him. He seems to have done lots of work on suspension so reading through his threads now, which are plenty :). There is a lot of info there from you guys too. I will get back here if I will still have questions :)

By the way my problem with stock springs is that they are too harsh on rough road. On smooth pavement I have no problems what's so ever. But when entering bad road the front is going mad and I have to reduce riding speed. We have this interesting road in our town, worst nightmare for suspension. It's is basically like an ancient road made from round stones. The ones like in 18th century. I cannot ride faster than 10mph on SV there, and it feels like I'm firining an automatic machine gun while riding mad bull in rodeo...

Now I assume that my suspension is stock. I maybe wrong. I bought SV only a month ago. It could be that previous owner already messed with the front. Back is stock with lowest preload.

Other thing I'm fearing is that the bike has evidence of front end crash and repair. Steering though feels very neutral, I can ride with no hands at speed no problem, but maybe forks ar sticking through their travel? The other thing that worries me is leaking oil seal. And the bike has only 4000 miles on the clock.

So my guess on the problems I have is either too much high speed compression damping due to heavy oil, or too much rebound damping due to thin, old oil that is also some missing due to leaking seal.

Would be nice to know the cause, but it's not that important, as I'm planning to reassemble forks, check all parts for wear and damage, and install the emulators. Just not sure about the oil weight yet, but I hopefully will after drinking from the knowledge well of suspension tuning :)

[Domas]

Just for the reocord -Different Bike - completely different setup! This guy/girl is talking about emulators and a pointy SV. 5W would pretty much remove all compression damping properties in this setup and is NOT advisable! :)

But isn't the compression adjustable on emulators?

[ThEGr33k]

Domas, I know I keep harping on about this, but it is most important... you set the sag using pre-load? If yes then it does sound like you dont have enough rebound (which I think you might already realise?) on if you are getting a recoil effect :( Hopefully the heavier oil will help you there! :)

Just for the reocord -Different Bike - completely different setup! This guy/girl is talking about emulators and a pointy SV. 5W would pretty much remove all compression damping properties in this setup and is NOT advisable! :)

Oh yea... was just pointing out how some bikes are different is all. :rolleyes:

[Domas]

Domas, I know I keep harping on about this, but it is most important... you set the sag using pre-load? If yes then it does sound like you dont have enough rebound (which I think you might already realise?) on if you are getting a recoil effect :( Hopefully the heavier oil will help you there! :)

Didn't check the preload yet. But it will be the first thing I'll do after reassembling the forks.

Another thing came into my mind and I don't think I saw it discussed anywhere. Is there difference in front load between SV650S and SV650(N)? I have the latter, and also since I'm long 190cm (6ft something) and have long arms, I sit very straight up, almost vertically like on some tourer. So I don't have so much weight on front as shorter rider would have given the same body weight.

Is this something to consider or it doesn't matter practically? It would explain why the front is so jumpy and would confirm that stock springs are good enough for me.

[ThEGr33k]

The N is a little more sit up as its got riser bars and I believe a different position for the rear set (foot pegs) so yea different. You'll have to ride it like Ben Spies, lean forward and have your elbows points out :p