Fork Height Versus Shock Preload

[sv650_ ck]

Does increasing shock preload have the same effect as sliding the fork tubes up in their clamps? Is their any reason why you would do one over the other? 1/2 turn of shock preload seems to make quite a bit of difference in handling but I haven't tried fork height adjustments.

[quailchaser]

Fork height in the clamps does not affect the handling characteristics of the Forks. The forks will work the same whether they are in the stock postion or slid up in the clamps.. However, it will affect the handling of the bike.

Changing your shock pre load affects both the handling of your shock and the bike. It changes where the stoke of the shock starts while you are riding. It also changes the ride height. For the shock to work like it is supposed to, you need the correct preload.

Hopefully one of the suspension GURU's will chime in as to the specific details.

[OverTheHill]

Sliding the forks up in the clamps (or raising the rear) will make it turn quicker - it will tend to knife. Sliding the forks down to raise the front (or lowering the rear) will slow down the turning to the point of pushing but it will be more stable in open high speed terrain. It's quicker and easier to adjust the forks and you don't mess up the sag (imo).

[sv650_ ck]

Sliding the forks up in the clamps (or raising the rear) will make it turn quicker - it will tend to knife. Sliding the forks down to raise the front (or lowering the rear) will slow down the turning to the point of pushing but it will be more stable in open high speed terrain.(imo).

Getting the KDX to handle well in both tight trails and open sandy sections is difficult. Will have to compromise and find an unhappy median. Thanks for the info.

[canyncarvr]

Does increasing shock preload have the same effect as sliding the fork tubes up in their clamps? Is their any reason why you would do one over the other? 1/2 turn of shock preload seems to make quite a bit of difference in handling but I haven't tried fork height adjustments.

The only reason you would increase 'shock preload' is if it is NOT set correctly in the first place.

Your reference to '1/2 turn' regards bike sag settings I presume. Generally (emphasis on the general part) that setting is 1/3 the travel of the rear suspension.

Front forks are generally raised/lowered to 'level' the bike...to make the front match the rear.

You wouldn't do 'one over the other' as each is to be set...well...correctly.

The simple answer..do the two mentioned adjustments have the same effect..? is 'No.'

If 'increase preload' on the shock means more squeeze..that lowers the rear which would be similar in effect to lowering the forks in the clamps.

[Roland C]

Have you done anything to the suspension or is it stock? There is a lot you can do with your suspension to get the bike to handle better.

[sv650_ ck]

Have you done anything to the suspension or is it stock? There is a lot you can do with your suspension to get the bike to handle better.

I've actually done quite a bit. Springs and GV's in the front, both fork and shock revalved by JF, WER damper.

Compression set high and sag set around 105mm and it feels great in the sand but will occasionally washout in the tight harder soils. Set up loose and the sag around 95mm and it handles likes it's on rails in the tight stuff but oversteers and knifes around in the sand. Probably just need to improve my riding skills which I'll be able to do when my radiator comes back from Mylers.

[IdahoCharley]

CC wrote "If 'increase preload' on the shock means more squeeze..that lowers the rear which would be similar in effect to lowering the forks in the clamps."

Doesn't increasing the shock preload RAISE the rear and also transfers more weight forward onto the forks which WOULD BE similar to lower the forks in the clamps.


SV650 - sounds like the compromise shock preload is 100mm to me.


I would make sure the bike is balanced spring wise then set the shock preload and adjust the height of the forks in the clamps for best handling. Its always going be a compromize setting if you ride various terrian unless are a fanatic about suspension. For the majority of riders you try to find a setting that works well 80% of the time and live with it during the other 20%. For me I might make a few click changes between riding in the rocks and riding in the sand and neither is likely the "ideal" setting but its not the suspension holding me back - it old age and ability.

[canyncarvr]

CC wrote "If 'increase preload' on the shock means more squeeze..that lowers the rear which would be similar in effect to lowering the forks in the clamps."

Doesn't increasing the shock preload RAISE the rear and also transfers more weight forward onto the forks which WOULD BE similar to lower the forks in the clamps.

I may be as backwards on this as I was the last shock go-round...but that's why I provided my own definition.

To raise the backend, the shock spring is released, NOT further compressed.

So...IF 'increasing the shock preload' means to compress the spring (more squeeze..make the spring shorter...turn the adjusters toward the rebound adjuster...clockwise from the top of the shock...etc), that action lowers the rear of the bike.

As obviously, if 'increasing the shock preload' means you loosen the spring..the bike goes 'up'...sag is reduced.

It's the idea of 'increasing' actually meaning 'reducing' that might be at issue in this case.

...again...hence the definition. I don't know if SV650's defintion is the same or not...but the correct answer can be had knowing the basis on which the statement was made.

From a write-up on shock setup: Lack of traction due to a stiff shock? Decrease shock spring preload. (From here)

If 'too stiff' in this case means 'too tight' and/or 'too short', then 'decrease' means make the spring less tight or 'longer'.

Semantics aside (what are words except groups of letters considered to have a particular meaning anyway?) it should be obvious which direction you move the shock spring to attain the desired effect.

re: 'will occasionally washout in the tight harder soils.'

'Knife' and 'washout' as applied to the frontend may indeed be addressed by changing the heighth of the forks in the clamps...or the shock sag. It is also controlled by rebound control...which is not adjustable (save for changing oil viscosity) in the OEM KDX fork.

From the tenor of SVs posts...I'm sure he knows all this...and is probably wondering what the hell all the Webstering is about.

('fer instance..in MY case, it's old age and INability! )

Isn't this fun?

[Roland C]

I did a little playing with my bike last year in an attempt to get my short butt a little closer to the ground. I did that, at first, by unthreading the two collar rings on my rear shock. That DECOMPRESSED the spring and LOWERED the back end of my bike. I believe that's called INCREASING the sag because the back end of the bike now sits lower under its own weight. Before I did this, I would have thought it would be the other way around. All I know is that by lessening the preload on the shock spring, I was able to touch the ground better.

I ended up fabricating my own set of longer dog bones to get the back end down and raised my forks in the triple clamp. That way the bike was still in balance and the back wasn't so squishy. That gave me probably 1 to 1-1/2 inches and now I can touch with both feet at the same time!

With CC's wealth of knowledge and experience it is hard to disagree, but I think I agree with IdahoCharley on this one. Unless, of course, CC by providing your own definition you are actually saying the same thing??? I hate this terminology thing because now I'm not even sure what I'm saying

All that said, my answer to original question:

Does increasing shock preload have the same effect as sliding the fork tubes up in their clamps?

Again, depends on definitions I suppose. Increasing shock preload (tightening the rear spring) would raise the back end of the bike (against logic, but experience says so). In essence it would have a similar effect as raising the forks (lowering the front end). That will quicken the steering and make it less stable at speed.

Is their any reason why you would do one over the other?

Yes. Raising the forks is going to make it turn quicker, but it won't change the firmness/suppleness of the forks. Raising the rear (increasing preload on the spring) will stiffen the rear suspension.

That would be my take as best I understand it. Maybe taking some preload off the spring would raise the rear when it is unweighted, but as soon as you sit on it your butt is going to be closer to the ground. Hope that all made sense. CC - if I'm way off, please enlighten me. You may need to include pictures, though, because I can be a little dense.

[canyncarvr]

Well....here we go agin.

But THIS time it didn't take a month...I think?

First off...I don't know where this supposed wealth of anything is, but it's likely all a fabrication!

There are a couple of 'backwards' things when it comes to shock springs...like if you have too little free sag, your spring is too light (too low a rate).

But this one is fairly simple..still I get IT backwards all the time. Don't know the whys of that.

Come to think of it...IC is the one that harped on me long enough LAST time this was discussed until I finally saw the light.

Thanks (again..and not for the last time for sure) IC for doing it again.

Still....misadjusting the back to make up for something wrong in the front is not right. Adjust the shock as you should, taking into account both race AND free sag to arrive at the correct shock/spring setting. Adjust the forks as you should, considering sag, but more the fork reaction to commonly specified input (HSC, LSC, bottoming, etc.)

To be ...uh..clear? (ha!)..

re: 'unthreading the two collar rings on my rear shock. That DECOMPRESSED the spring and LOWERED the back end of my bike.'

Yes it does.

re: 'by lessening the preload on the shock spring, I was able to touch the ground better.'

Yes.

...your free sag is likely goobered..but that's another issue.


Not that it matters, but I do know which way to turn 'stuff' to make happen what I want to have happen. I can watch a suspension (some other rider) for a bit and know what needs to be done to 'fix' it. I ride my own bike and know what to do with it, too.

I guess I'm defending myself as something other than a complete maroon. Anyone that knows me can laugh themselfs silly over THAT one!

[Roland C]

My free sag was goobered, hence the addition of longer links so I could un-goober the sag

[IdahoCharley]

As long as we all understand what it take to get the job done - This is sometimes just like the government place I used to work - terminalogy drove me nuts there - i.e. say the word "significant" and people would call meetings to hammer on you: say the word "contamination" and people went ballistic. BTW - I was in the Safety/Hygiene environment.

[canyncarvr]

Wow!

Can you even imagine what would happen if there was EVER 'significant' AND 'contamination'!

This site has made significant progress. No contamination was found.

TIME FOR A MEETING! HE'S DOIN' IT AGAIN!!!'

[IdahoCharley]

CC - I hope we get a chance to meet in person. I really enjoy your humor.