Rear suspension sag?

[marks]

Hi

I just fitted a new rear shock and spring to my klr.

the sag before was 8cm
the sag with the new bits was 5 cm

I presume this means I have too much preload on the new setup?

except the actual ride hide with me on the bike hasn't changed - that is the unladen ride height has dropped 3cm which implies I don't have enough preload

I think the klr has about 200mm rear travel and 8cm is regarded as about right.

I am very confused :(

[ducatijim]

You like me Mark, no rides today?

The only variable in ride height( weight aside!) is preload, yes.

I'm far from competent here, but the greater the sag laden,( within reccomended range) the more compliant the ride should be.

I would have thought thou, that 8cm static was a bit much? How much sag is there loaded?

Sorry, prolly no help at all?

[marks]

You like me Mark, no rides today?

The only variable in ride height( weight aside!) is preload, yes.

I'm far from competent here, but the greater the sag laden,( within reccomended range) the more compliant the ride should be.

I would have thought thou, that 8cm static was a bit much? How much sag is there loaded?

Sorry, prolly no help at all?

nope - no rides today :(

bike maintenance day (always something to fix/unbend/replace)

thanks for the response

I whacked a bit more preload on so it sits a bit more stably on the side stand and I'll ride it for a while and see how it feels

cheers

Mark

[NordieBoy]

Usually around 15% static sag and 30% rider sag.

3-4cm static and 6-8cm rider.

Sounds like you've got a heavier spring now too?

[marks]

Usually around 15% static sag and 30% rider sag.

3-4cm static and 6-8cm rider.

Sounds like you've got a heavier spring now too?

oops - I only measured the difference between the bike sitting on its wheels and the bike sitting on its wheels with my fat bum on it - so I suppose I'm talking only rider sag (50mm - 25%).

and yes - of the 4 spring rates on offer I got the 3rd strongest one.

now I need to get out and do something bumpy and test it out

[warewolf]

oops - I only measured the difference between the bike sitting on its wheels and the bike sitting on its wheels with my fat bum on it - so I suppose I'm talking only rider sag (50mm - 25%).Nope, that's the difference between static & rider sag... Padmei made this same mistake recently - must be a KLR feature! :laugh:

Measure the free length, wheels off the ground so the suspension is topped out. Call this A.

Measure the length with the bike on its wheels, call this B. Static sag is A-B.

Measure the length with you on the bike in normal riding gear, call this C. A-C is rider sag.

The trick is, you set the preload to get the correct rider sag. The subsequent static sag tells you if the spring is correct. Too little static sag means the spring is too light, you've over-preloaded it to cope with the rider weight. Too much static sag means the spring is too heavy, you've backed off the preload too far.

I wouldn't worry too much about was it was with the old spring. Aim to get it correct on the new spring. Lots and lots of good stuff on the interweb about this.

[warewolf]

Try Teknik racing bike setup guides (http://www.teknikracing.com/teknikal-library/setup-guides).

[ducatijim]

See Mark, I told you I didn't know much about this!!!!!

Good info.

[buggsubique]

vaguely related story ... my DRZ 400 stock spring was too light so I compensated by winding up the preload. Problem I found was it made the bike shite to ride downhill - esp gravel downhill roads. the geometry was all f*cked up and it was difficult to keep the rear under control. I did the sag equations and I should have had a heavier spring but I was too pezza and suffered for it...

[marks]

Nope, that's the difference between static & rider sag... Padmei made this same mistake recently - must be a KLR feature! :laugh:

Measure the free length, wheels off the ground so the suspension is topped out. Call this A.

Measure the length with the bike on its wheels, call this B. Static sag is A-B.

Measure the length with you on the bike in normal riding gear, call this C. A-C is rider sag.

The trick is, you set the preload to get the correct rider sag. The subsequent static sag tells you if the spring is correct. Too little static sag means the spring is too light, you've over-preloaded it to cope with the rider weight. Too much static sag means the spring is too heavy, you've backed off the preload too far.

I wouldn't worry too much about was it was with the old spring. Aim to get it correct on the new spring. Lots and lots of good stuff on the interweb about this.

thanks Colin

I'll check it again tomorrow :doh:

[Eddieb]

Wanna do mine next? it's all black magic and voodoo to me.

[Frodo]

Try Teknik racing bike setup guides (http://www.teknikracing.com/teknikal-library/setup-guides).

Very interesting. I've just used stock settings and seems to work for me. But perhaps I can do better. Anything for dual sport, i.e. between the road racers and motocrossers?

Thanks, Bob

[Woodman]

Tried setting up mine after the intiminatorerers and the raising link fitment and couldn't get any where near the percentages ww talked about. One would effect (affect) the other so I just set it up close and its definitely better (I think). It would be good to have a choice of springs and a decent shock to play with in the first place though.
Be interested in your thoughts after a decent hoon though marks.

[XP@]

oops - I only measured the difference between the bike sitting on its wheels and the bike sitting on its wheels with my fat bum on it - so I suppose I'm talking only rider sag (50mm - 25%).
I've done that too, and totally mucked everything up the preload in the process.

To fix it (with the advice from my suspension tech) turned out to be easy!

"Forget about rider sag - you cannot set it by yourself, also you are effectively setting it anyway when you adjust the pre-load"

So I re-set the pre-load to the mid point and the static sag to 25mm (about 15% of total). Fortunately this was damn near perfect all that was needed was a bit of hardening up (initially by 1/4 turn then I backed it off by 1/8th turn)

If you really get stuck then contact this guy: www.dukicperformance.com (he does bikes not websites) he is in Lower Hutt, and really knows his stuff. He re-built an "un-rebuildable" rear shock and installed cartridge emulators (plus a few other bits) for me. The emulators put in my front forks were perfect first time (and a bloody good price compared to others I was quoted).

[warewolf]

vaguely related story ... my DRZ 400 stock spring was too light so I compensated by winding up the preload. Problem I found was it made the bike shite to ride downhill - esp gravel downhill roads. the geometry was all f*cked up and it was difficult to keep the rear under control. I did the sag equations and I should have had a heavier spring but I was too pezza and suffered for it...Very related story. Preload only fine-tunes your correct spring. The spring does the primary job of supporting the bike, damping is mainly there to control the spring. Don't have the correct spring? No amount of preload will fix it, and going to extremes of preload (over/under) can introduce worse effects than moderate preload on the wrong spring.

eg High preload on a soft spring makes the initial travel harsh but won't stop the suspension blowing through its stroke, whereas a stronger spring will be softer initially but firm up appropriately.


Very interesting. I've just used stock settings and seems to work for me. But perhaps I can do better. Anything for dual sport, i.e. between the road racers and motocrossersSorry that site is probably a bad example, I see it is mostly race-focused and a little more detailed - search for more, there is heaps online. But the principles are the same, refer Nordieboy's percentages listed earlier. Try google?


Don't forget these numbers are a starting point - like the clickers - so vary them to suit yourself. Eg as ducatijim suggests, setting the preload at the softer end of the suggested range gives a more compliant ride. But I strongly suggest if you don't really know what you are doing (ie all of us who aren't pro suspension ppl) that you start with the suggested settings, see what it feels like, and vary from there. Experiment - make one change at a time, go for a ride on a test loop, see how it behaves. Make another change - ride the same loop. Did that work better? Did it introduce ill-effects somewhere else in the loop? etc

[NordieBoy]

Get a copy of "Dual Sport Suspension" by Ned Suesse (Neduro) & James Siddall (Super Plush Suspension).

[Padmei]

Is it possible to get more travel out of suspension without raising seat height? I had a look under gonzo & wondered how other bikes get longer travel with a linkage setup.

If we're comparing to mountain bikes the KLR, Dr etc have a 4 bar linkage such as Giant, Specialised etc, KTM, I take it, have their shock less linkages such as like my Santa Cruz?

Has anyone succesfully got more rear travel without putting their heads above the clouds?

Any helpful links would be appreciated

BTW hows the ricor rear going Mark?

[marks]

BTW hows the ricor rear going Mark?

its not

I spent the day following my son around the Mungatooks on trail bikes.

I'll take it somewhere lumpy next weekend and give it a decent test out

[Padmei]

What brand fork oil did you use with your intimators?

[marks]

What brand fork oil did you use with your intimators?

Spectro 5W

did you check you had the right size iniminators?

[Padmei]

Yep just gonna change the oil & go from there. Now back to the scheduled programme.

[warewolf]

Is it possible to get more travel out of suspension without raising seat height? I had a look under gonzo & wondered how other bikes get longer travel with a linkage setup.

If we're comparing to mountain bikes the KLR, Dr etc have a 4 bar linkage such as Giant, Specialised etc, KTM, I take it, have their shock less linkages such as like my Santa Cruz? In a word... no. The only way you'll get more travel is by extending the wheels down (lengthening the forks and the stroke of the shock) because there's no room to extend upwards - the wheels will hit the guards and the bash plate will deck out at full compression.

The linkages don't really have much bearing on the travel, in the sense that they might limit or extend how much you can have - they don't. They really achieve two things: give you a rising rate on the spring force so that the suspension firms up as it moves through its stroke (this is what lowering links corrupt), and multiplies the shock travel vs axle travel - usually at around 1:3 - so you can have a smaller shock.

btw the KTM's have linkages... that is one of the differences between the gentle LC4 <del>(& LC8)</del> and the hard-out off-road bikes which don't. And after ten years of trying to get the PDS system to work really well, the latest KTM has linkages again.

[Woodman]

I seen a thread somewhere where a guy put a linkless set up on his klr. It was not straight forward apparently. The raising link I got on mine has certainly stopped the rear from bottoming out nearly as much, and also I have added more dampening since fitting it so the ride is a bit plusher too.e.g. less pogo stick like. But the bike does sit about an inch higher so is quite tallish now.

[marks]

But the bike does sit about an inch higher so is quite tallish now.

it seems to need it though

the biggest problem I have with mine is smacking the under bits into things when the suspension fully compresses

I'm hoping the more controlled rikor bits will reduce the 'blow through the suspension travel - bang - something else underneath breaks' stuff

maybe I should stay away from the triples only do single backflips

[cooneyr]

....btw the KTM's have linkages... that is one of the differences between the gentle LC4 (& LC8) and the hard-out off-road bikes which don't. And after ten years of trying to get the PDS system to work really well, the latest KTM has linkages again.

psssst - the LC8's have PDS shocks.

This is all interesting reading. I would have though that my 950 S has too soft fork springs cause I've bottomed out the front more than once. Got wifey to help me check sag etc the other day and found that the both front and rear sag's are pretty damn close given my weight (using 15% 30% for Static Dynamic). Might have to try more compression damping for the front?

I do know that the shock's rebound damping is excessive though - it has a tendency to pack down over corriguations - couple of clicks less makes a noticable +ve difference but I must try less damping. My biggest problem is the tendency to lock up the rear wheel under brakes. I'm guessing that less rebound damping would help with this as well but I'm not totally sure. Any advise on this?

Cheers R

[warewolf]

psssst - the LC8's have PDS shocks.Oops, fixed above.


This is all interesting reading. I would have though that my 950 S has too soft fork springs cause I've bottomed out the front more than once. Got wifey to help me check sag etc the other day and found that the both front and rear sag's are pretty damn close given my weight (using 15% 30% for Static Dynamic). Might have to try more compression damping for the front?A few more clicks of compression damping, or add some oil. The other thing to remember is that you probably should bottom out the suspension sometimes - gently and controlled, that is - because if you aren't, you aren't using your suspension to its best.

btw what numbers do KTM suggest in the book? You may find more specific values for your kit, esp if they use top-out springs, and the PDS. I know on the SX/XC KTMs the PDS is renowned for being very sensitive to preload (like KTM quote 15mm range not 30mm, and experienced tuners say only 3mm :argh:).


I do know that the shock's rebound damping is excessive though - it has a tendency to pack down over corriguations - couple of clicks less makes a noticable +ve difference but I must try less damping. My biggest problem is the tendency to lock up the rear wheel under brakes. I'm guessing that less rebound damping would help with this as well but I'm not totally sure. Any advise on this?Definitely back off the rebound damping ASAP!!! Dr Robert cites excessive rebound as a #1 cause of otherwise inexplicable crashes (road/track presumably). IIRC he says ppl tend to set the rebound a couple of clicks too hard - so set it to where you are happy, then back off a bit. It should feel a little too plush & loose not super firm.

Locking up under brakes can mean the wheel isn't rebounding fast enough to stay on the ground. Or you just don't get along with sharp brakes - lower the pedal, and/or change sintered pads to organics, the latter having less bite more feel.

Have a dig around on the net, there are lots of helpful articles about dialling in the suspension, what to change for various problems. I haven't seen the dual-sport one Nordie suggests, but want to. :yes:

And unfortunately, with us living in the major compromise world of adventure where we face a massive variety of conditions, it may be impossible to get the suspension working optimally across all conditions. So like changing tyre pressures for seal/dirt, you may need to have suspension settings for seal/dirt. I do that for the 640A usually by riding from one to the other and noticing the suspension needs a tweak :doh:and click here or there improves things dramatically.:woohoo:

[Padmei]

You have to admit it is an interesting field for trial & error.

I very rarely use my back brake as it locks up very very quickly. I'm wondering if playing around with rebound will change that.

[marks]

You have to admit it is an interesting field for trial & error.

I very rarely use my back brake as it locks up very very quickly. I'm wondering if playing around with rebound will change that.

getting your iniminators working properly will help heaps with back brake lockups as it reduces weight transfer to the front when the forks blow through their stroke with chronic brake dive. (this assumes you use your front and rear at the same time)

[marks]

finally got around to measuring the settings properly...

185mm total tavel
big sag = 25mm = 13%
rider & bike sag 75mm = 40%

sounds like it needs a bit more preload? - but I'll ride it for a bit and see how it goes

[NordieBoy]

finally got around to measuring the settings properly...

185mm total tavel
big sag = 25mm = 13%
rider & bike sag 75mm = 40%

sounds like it needs a bit more preload? - but I'll ride it for a bit and see how it goes

Sounds like the spring may be a bit strong solo but should be about perfect with a bit of gear on the back.

[Woodman]

Sounds like the spring may be a bit strong solo but should be about perfect with a bit of gear on the back.

Have you ever seen marks bike without gear on it???

[warewolf]

185mm total tavel
big sag = 25mm = 13%
rider & bike sag 75mm = 40%

sounds like it needs a bit more preload? - but I'll ride it for a bit and see how it goesRide and see, but yes you need to try more preload. From the numbers you also may need more spring. Static sag is good now @ 13%, but rider sag is too much @ 40%. If you add preload to fix (reduce) the rider sag, the static sag will also reduce. It could shrink to dismal levels which would indicate an over-preloaded weak spring. But it might not; the two numbers are not directly proportional.

Is this a new Ricor shock? If so, do they recommend particular sag numbers?

[Woodman]

What is the relevance of static sag? surely it is not important because it doesn't include the riders weight. or is it just a guide to measure the strength of the spring when the rider sag is measured. Or am I confused?

[warewolf]

Not confused, probably correct.

[NordieBoy]

Oops...

13% is good 40% should be around 30%.

Get a stronger spring.

[cooneyr]

Oops...

13% is good 40% should be around 30%.

Get a stronger spring.

Glad somebody corrected you. I was confused for a moment :wacko:

Cheers R

[marks]

Is this a new Ricor shock? If so, do they recommend particular sag numbers?

yup

havent found anything on their site yet