Springs

[Tack]

Just out of interest, does anyone here know what the standard spring rate is/was for their bikes and what spring rates a suspension expert/specialist has recommended and fitted to suit their weight or riding application?

I ask because I've been to a couple of track days and they offer a suspension set up service which they promote at the drivers briefing. The spiel they give at the briefing is that the standard bike is made to take a passenger and therefore the rear springs, for example, are much heavier than what's necessary for a solo rider doing track days.

Fair enough concept, I thought, however the Kawasaki workshop manual (not owners manual) offers the preload length of 180mm for the standard rear spring on my 2007 ZX10R for a 68kg solo rider without pillion or accessories.

While specifying the preload doesn't necessarily mean that spring rate is based on a 65kg solo rider without accessories I wondered why they would even specify such a figure if it wasn't far from the truth!

Logically, to me anyway, If you were really selling a bike with spring rates for a rider and passenger why wouldn't you specify settings for that exact scenario with your standard preload?

So I thought an industry suspension expert might give me a clue and when I got my steering damper rebuilt to race specs I asked the guy there and he said that the front springs on my bike were pretty good but that generally the back was a bit hard and needed a softer rate and closer to my weight.

fair enough....so seeing as I'm getting a new rear shock soon I thought I would do a bit of investigation on spring rates and found this site from race tech:
http://www.racetech.com/

So if you you click through sports bikes and look up your year and model etc, they give you some info on what the American version of the bike has.

The interesting part is that they allow you to specify your bike weight and your weight and give you a recommendation on what spring rates you should run.

Interestingly they reckin' that I the bike has an 8.3 kg/mm spring in the rear and with my weight and bike weight I should be running a 9.071 kg/mm spring!

That's a heavier than standard spring and I weigh only 70kg!

http://racetech.com/ProductSearch/2/Kaw ... 0R/2006-07


If I plug in a heavier rider of say 95kg...much heavier spring.

Anyway, I realise that motion ratios (or leverage ratios) for each model of bike are different (as well as bike weight and distribution etc) so direct comparison isn't possible or advisable but I was just interested in comparing straight changes on your own bikes to see whether the spring rates went up or down.

So anyone got any numbers?

[Blurr]

Calling Born Green!!!!!

[fireyrob]

Calling Born Green!!!!!

You should be an administrator!

Tack, Sorry cant help with humbers but I remember my 07zx10r was very softly sprung. After being reamed on suspension mods I ended up selling the bike. Heavier springs front and rear helped for my 95kg fatarse but as for specifics sorry Im of little help

[born green]

Was going leave this alone!!! cause this will get me flack again hehe!!
read what u wrote tack, dont kno anything about that.
Going by what stewie winton has told me, he recommend a heavier spring (track work, he wasnt talking about road) my orig shock was resprung with a 10kg spring, and setting up sags went well.
Since fitting a ttx ohlins, i ran the stock spring(9kg) thats what it came with.
when i fitted it, i couldnt get sag right, couldnt get to spec. did a ride day, and stuffed a new 200 sort dunlop, as it turned out, stewie was at broady that day, so had a chat, he said no way was the 9kg ok, , was waiting for a new spring anyway. fitted a 11kg spring, did sags ect, and dialed it in to spec straight away, stewie allso told me that with wayne's bike, they were running a 14kg at one stage.but none of us can ride as hard as wayne of course!!! he has told me a occasion, that the 06/07 had a lot of squat problems, hence the heavier spring.and thats about all i kno about spring weights, my bike seems fine with the 11kg, and once comp and preload sorted, tyre wear is good.
that doesnt answer the questions u asked tho. as he was the TKA suspension man at that time, maybe its worth a call to him, and pick his brain.

[born green]

Was going leave this alone!!! cause this will get me flack again hehe!!
read what u wrote tack, dont kno anything about that.
Going by what stewie winton has told me, he recommend a heavier spring (track work, he wasnt talking about road) my orig shock was resprung with a 10kg spring, and setting up sags went well.
Since fitting a ttx ohlins, i ran the stock spring(9kg) thats what it came with.
when i fitted it, i couldnt get sag right, couldnt get to spec. spring to soft. did a ride day, and stuffed a new 200 sort dunlop, as it turned out, stewie was at broady that day, so had a chat, he said no way was the 9kg ok, , was waiting for a new spring anyway. fitted a 11kg spring, did sags ect, and dialed it in to spec straight away, stewie allso told me that with wayne's bike, they were running a 14kg at one stage.but none of us can ride as hard as wayne of course!!! he has told me a occasion, that the 06/07 had a lot of squat problems, hence the heavier spring.and thats about all i kno about spring weights, my bike seems fine with the 11kg, and once comp and preload sorted, tyre wear is good.
that doesnt answer the questions u asked tho. as he was the TKA suspension man at that time, maybe its worth a call to him, and pick his brain.

O, i forgot about the front, different views on the front, i cant remember what weight springs im using would have to root around in ths shed to find box. only going by what stewie and wayne have told me, the main problem with the 06/07 is in the rear end,swingarm to short for starters ect. i dont have any front end problems really, tho a couple of ride days ago, i was playing around with settings, and started to get front end chatter, quiet bad, came in and backed off comp, 2 clicks, back out, no chatter, so front is prob close to where it shoud be??

cheers

[Nelso]

It will also depend on how hard you ride the bike as well as your weight. My trackie was owned by Blurr who is a bit lighter but also lots faster than me so the suspension was set up quite hard when I bought it because he brakes and gets on the throttle far more aggressively. It meant I didn't have to change much to get it set up to my weight.

If you're only 70kg I would think you would be able to get away with winding your preload up with the standard shock until you get fast enough to need suspension upgrades. Wattie was able to do sub 1:40s around Eastern Creek with standard suspension and he's nearly a hundred kegs.

[Tack]

thanks for the replies. All good info.

I was just interested mainly due to both the briefing spiel and the suspension guy saying that in general, the rear springs were too hard.

Seems that possibly heavier rear springs are the go. It's a bit unfortunate that so often generalities are used by bike people because it leads to all those myths that seemed to be perpetuated throughout the bike world.

But I'm a suck and see sort of guy. I try it and see if it feels better and if it's faster. If it isn't I try something else.

[born green]

Had me thinking!!! yer i kno
Draged out book. for 06/07 factory setting is for 68kg rider.
forks. spring preload 17mm from top of adjuster
Rebound 10 clicks out
Compression 10 clicks out
Rear.
rebound 2 turns out.
Compression 4 turns out.
But who of us is 68kg in gear!!! not me. that may suggest that with a heavier rider, that it may be to soft a spring from the factory?? any idea's on that? lets face it most of us are prob a fair bit heavier than 68kg in gear, im around 86/88 in gearb

[Strika]

I think they are talking shit mate. Most modern bikes are built for a 65kg midget with no luggage, pillion or gonads. I have NEVER had to go softer in spring rate when changing suspension on ANY bikes I have ever owned. Perhaps there might be the odd Ducati out there with god hard springs, but 99.999999999% of roadies are way soft out of the box.

As for spring weights, it also depends on the linkage ratio as to what spring as each linkage produces differing ratios requiring different springs. But I know my rear on the racer has a choice of 8.5 and 9kg springs depending on how fat I get.