Fork adjusters

[northwind]

Originally Posted by Blue_SV650S

As you well know northy, compression damping is there to slow the rate at which the spring is compressed; not to provide springiness! Basically if you put treacle in there you would struggle to ‘bounce’ the suspension as it is so heavily damped, I suppose it might give the illusion of being ‘stiffer’ … However in actual fact, stick a 10kg weight on the front and the nose of the bike will go down X mm just the same as if you put water in there … the only difference is that with the treacle it would take much longer to sink to X mm!! …

Yup, but that's still relevant, since rate of reaction to a force is critical in a fork... If you load up the front by, say, 50N on braking in one second, a fork with 5W oil will dive more dramatically and uncontrollably than a fork with 20W oil (I know you know this btw, I'm soliloquying to the audience ) And when people talk about the forks being too soft, generally it's this reaction which they're most bothered by, since it feels terrible and it knackers your traction. Most people couldn't care less how much the bike compresses under your weight (though of course it's important! It's just not the thing most folks notice, which is how you get people with far too much preload sitting right on top of their travel)

But of course, sometimes you want the fork to react faster- if you load it up the same by riding over a rock you want it to get out of the way. So here your treacle would be a complete sod, the event it's reacting to is over long before it can fully react and you end up with the whole bike kicking. Again, impairs your grip, just as an overstiff fork would. So you want a fork that's resistant to braking dive but pliant to impact.

And then of course, you've got the rebound damping, which is what Blue was talking about earlier- with the SV forks the damping both ways is controlled by the oil, change the oil alone and you increase both compression and rebound damping, so the fork returns slower. And then you get what I've always called packing, but what blue calls pump-down, the next event happens before the bike's recovered from the last, and it ties itself in knots. Get that on the rear, and you have the best recipe for a tankslapper. Get it on the front and you have a huge loss of grip among other things. It's bad news. Increase the spring rate though, and the increased damping is offset against the fact that the fork pushes back harder.

But... All about finding a balance. If the stock oil wasn't underdamping the front as standard- and personally I think it is- it certainly is once it's been in there for 10000 miles. And as Embee said, not all fork oil is equal, 2 different 10Ws may act totally differently. I think we put Bel-ray in one, and Silolene in another, and you really could feel the difference. I reckon you can increase the damping enough to make a difference without causing severe problems, though. If you go nuts and fire in 20W or even 15W, expect problems, but a fairly viscose 10W or a light 12.5W could work out well.

That said, springs are only £70, that's less than most cosmetic mods and it makes the bike work. It's not a mod, it's a correction, it's just like buying shoes the right size.

This message is too big, I'll make another

[northwind]

So, emulators. They're ace. I pretty much agree with every word Blue said up there. Fairly simple, not externally visible, quite effective. The only sort of cavea I'd put on it is that I did my entire GSXR front end swap for less than a set of springs and emulators, and if you're the right weight for the stock GSXR parts there's no comparison there, you don't have to be fast to benefit either (as anyone who's seen me ride knows!) If you're heavier, you have to chuck money at GSXR forks to get them to work right for you too, for a big'un emulators and springs set up right is better than a true cartridge fork with totally soft springs.

But, first things first, springs and oil is pretty cheap, it's very effective, it's simple to do, and if you do decide to upgrade to emulators afterwards you don't lose a penny as the springs will still work. I'm not going to say it's essential, but it's a shame to have a £4000 bike not working properly for the sake of £100 worth of parts.

I've learnt more about compression damping reading this thread than I have in reading magazines and MCN for the past 11 years.

So, next...rebound damping!

Matt

Rebound has been touched on above, but in a nutshell, rebound damping is there to control the rate of the springs return – you imagine a spring fully squashed then suddenly let go … PING!!!!! … not good … tame that Ping with rebound!!!! … (if only we could tame our .org member Ping??!! )

There will be tones of stuff on the net about this if you are interested.

This website is referenced quite often on here, a good read should answer your above question (and then some).

Give it a read and if you need anything clarifying further, then post it here and I am sure the .org collective intelligence should be able to help

Oh and northy, yep, agree if the oil is not the correct weight to start with then changing would benefit things!!

I was just pointing out that if you are 18st, your forks problem is not best solved buy running stock springs, but with ‘crude’ oil to stiffen!!!

Oh yea, gotcha there blue. I've never thought about suspension and springs before and stuff, i know its all there and what it does but never the full dynamics, hence why im only just learning now.

You guys should teach!

Matt

Oh and a good way to 'stiffen' the front end, but yet retain initial compliance is to reduce the 'air gap'…

Think of the forks as a sealed unit, after setting the stock oil level, there is some air in there between the top of the oil and the cap. When the forks are compressed, the area inside the forks is effectively reduced!! Therefore this bit of air is also compressed, and compressed air acts a bit like a spring!! – i.e. it wants to return to its former state and therefore provides a force!!

Reduce the initial amount of air, keep the same travel, that air gets is compressed more, it therefore has a greater return force

What is also cool about using air gap is that it is ‘progressive’ you can have nice softer springs that won’t be allowed to ‘bottom out’ as near the end of the stroke the air compressions contribution is significant enough to help out!!

Before everyone goes filling their forks to the top … … you obviously need a bit of air in there else the forks would jam solid!! Suppose if you filled the forks to the brim when fully compressed and with springs in (not sure how you would do that!! ) then that would be the minimum air gap you could run

[northwind]

Originally Posted by Blue_SV650S

I was just pointing out that if you are 18st, your forks problem is not best solved buy running stock springs, but with ‘crude’ oil to stiffen!!!

Aye, totally agree with that, it probably seems like a logical extreme to some too There's a guy on SVRider, who will remain nameless, who's convinced that there's no need for emulators, cartridge forks, all you need is a set of .9 springs and 30W oil. He weighs 70 kilos. Why not just dispense with the forks and use a stepladder? But because it doesn't dive on the brakes, he thinks it's great.

It all sounds a bit academic to some, but I know at least one guy on this forum who's crashed because of a bad shock setup (far too much preload, right hander with a heavy camber and a ripple in the tarmac, wheel skimmed across the surface and chucked him into a ditch. Again, naming no names)

Originally Posted by northwind

But of course, sometimes you want the fork to react faster- if you load it up the same by riding over a rock you want it to get out of the way. So here your treacle would be a complete sod, the event it's reacting to is over long before it can fully react and you end up with the whole bike kicking. Again, impairs your grip, just as an overstiff fork would. So you want a fork that's resistant to braking dive but pliant to impact.

with cartridge fork you can tune brake dive to degree.

Originally Posted by alpinestarhero

.. i know its all there and what it does but never the full dynamics, hence why im only just learning now

Speaking more generically here, I think that it must help a rider to improve their riding if they understand - at least to a reasonable degree - how a bike works You can certainly detect better if your bike has a problem and catch it before it catches you

Originally Posted by northwind

Aye, totally agree with that, it probably seems like a logical extreme to some too There's a guy on SVRider, who will remain nameless, who's convinced that there's no need for emulators, cartridge forks, all you need is a set of .9 springs and 30W oil. He weighs 70 kilos. Why not just dispense with the forks and use a stepladder? But because it doesn't dive on the brakes, he thinks it's great.

It all sounds a bit academic to some, but I know at least one guy on this forum who's crashed because of a bad shock setup (far too much preload, right hander with a heavy camber and a ripple in the tarmac, wheel skimmed across the surface and chucked him into a ditch. Again, naming no names)

To me if one wants to ride well and faster, there gets a point where you need to have a bike that behaves itself ... changing settings arbitrarily or without an understanding of what you are doing is likely to end in tears!! But also suspension settings are a very personal thing, if Mr SVrider likes his forks to act as if they were made out of angle iron, then good luck to him!! ... I also think it is a bit of a joke when you get someone else to set your suspension up for you ... unless you give them a very detailed briefing, how the hell are they going to get it to ride how YOU like it?!!?

Being able to ride the bike 'feel' what is going on and then make educated adjustment has to be the way forward??

Suspension is a black art, but the SVs simplicity and lack of adjustment actually makes the job of tuning your suspension to your needs so much easier ...

Originally Posted by Blue_SV650S

Oh and a good way to 'stiffen' the front end, but yet retain initial compliance is to reduce the 'air gap'…

it only does in last part of travel and mostly used just to keep forks from bottoming.personally I dont like any progression,reason we use linear springs.
you can get same with selecting correct spring.or lengthening travel buy getting rid of hydraulic lock piece.