spring rate

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xmoto
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spring rate

Postby xmoto » Sun Jun 19, 2011 8:53 am

Hi can someone tell me what springs to use for a 260 pound rider thats with all my gear on

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MrZ32
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Re: spring rate

Postby MrZ32 » Sun Jun 19, 2011 9:37 am

chuck your info in here

http://racetech.com/ProductSearch.aspx? ... ke&year=08

and use the calculate spring rates... should give you an idea... so assuming your gear ways roughly 20 pounds

they recommend an 18.5kg/mm rear spring... which seems about right. the front spring calc is incorrect i think. and would leave the .95 in the front alone
08 SD, WP Dampener, 'Suspension Improvements" tuned sus (springs, valves, shim stacks ), KTM cowl, R&G carbon covers, Termi Pipes (from a duc 998), Grim990 Airbox, breather mod, SAS plates, tuneECU PDI tune, HM QS, JTM VS & DVS

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indy84
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Re: spring rate

Postby indy84 » Sun Jun 19, 2011 10:13 am

So how shuld interperet these results? mines an 06 standard springs i belive

FRONT FORK SPRINGS
Recommended Fork Spring Rate: 0.702 kg/mm (use closest available)
Stock Fork Spring Rate: 0.95 kg/mm(stock)

REAR SHOCK SPRINGS
Recommended Shock Spring Rate: 17.622 kg/mm (use closest available)
Stock Shock Spring Rate: 17.0 kg/mm (stock)
06 superDuke
90 RM 250
56 Norton dominator
brisbane, OZ

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MrZ32
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Re: spring rate

Postby MrZ32 » Sun Jun 19, 2011 11:26 am

I am running 0.85's in the front and a 16kg in the rear... I am around 78kg with gear on... Seems about right however soul have been happy with 0.9 in the front too.

Indy yours are 0.9 and 16 for front and rear... Prob fine but .9 & 17 would work better for you as you're a bit heavier than me
08 SD, WP Dampener, 'Suspension Improvements" tuned sus (springs, valves, shim stacks ), KTM cowl, R&G carbon covers, Termi Pipes (from a duc 998), Grim990 Airbox, breather mod, SAS plates, tuneECU PDI tune, HM QS, JTM VS & DVS

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MrZ32
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Re: spring rate

Postby MrZ32 » Sun Jun 19, 2011 12:03 pm

indy, after my last exam on friday... we will catch up and we can workout whether you are running correct sag settings... get you to take that for a ride, see how it all feels.

then if you like the bike with that setup (as changing the sag settings may change your geometry depending how out your setting are)... but we can record your current geometry for you anyway before the settings are changed. Also do you have a set of bathroom scales? if so i will bring mine over too so we can check weight bias with you on it and without you on it (make sure your tank is about half full).

then what I will do is chuck your details into the spreadsheet that i knocked up for my bike (with a few changes)... as you will have different rake/trail and swing arm angle values to me. we can then work out with what springs are required for your weight.... i have spent some time putting it together so that you could work out which spring rate is best... taking into account what the static sag is ideal and what rider sag is ideal.

you can cook up a treat, i'll bring some beer and we can spend an afternoon working it all out... how level is your carport?

and after, i might make the spread sheet available where you just input a few values and it will spit out some numbers for you.

regards

J
08 SD, WP Dampener, 'Suspension Improvements" tuned sus (springs, valves, shim stacks ), KTM cowl, R&G carbon covers, Termi Pipes (from a duc 998), Grim990 Airbox, breather mod, SAS plates, tuneECU PDI tune, HM QS, JTM VS & DVS

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indy84
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Re: spring rate

Postby indy84 » Sun Jun 19, 2011 12:57 pm

brother... that sounds great.... timing might be a prob its my brohers wedding this week... bucks night, rehersal, setting up and the actual wedding... what day can you come into the shop... need to finalise things for your bike so the work can start.

Oh! I'm 77kg... i have actually put on 7kg last month... its harder to do than it sounds
06 superDuke
90 RM 250
56 Norton dominator
brisbane, OZ

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MrZ32
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Re: spring rate

Postby MrZ32 » Sun Jun 19, 2011 1:01 pm

i will give your brother a call at the shop tomorrow... see what time works for him to call in etc...

im in no hurry... its your bike mate... any weekend is fine... just wanna start near mid day as i dont wanna do it during a cold night.. neck is stiffening up in the cold atm.

by the time we got to the 't' on saturday i could barely move was so sore.
08 SD, WP Dampener, 'Suspension Improvements" tuned sus (springs, valves, shim stacks ), KTM cowl, R&G carbon covers, Termi Pipes (from a duc 998), Grim990 Airbox, breather mod, SAS plates, tuneECU PDI tune, HM QS, JTM VS & DVS

xmoto
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Re: spring rate

Postby xmoto » Sun Jun 19, 2011 5:41 pm

thanks for the info and help mrz32 can't wait to hit the twistys with the right springs

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Re: spring rate

Postby robban75 » Mon Jun 20, 2011 6:15 pm

whats the std spring rate mounted from factory? (sd 07)
2014 superduke 1290R
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SDNerd
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Re: spring rate

Postby SDNerd » Fri Jun 24, 2011 9:59 pm

While there are a lot of threads on springs, rates, etc. There isn't a clear consensus on what's "right" for a given rider's weight and use of the bike. It seems that the traditional setup "guidelines" more or less go out the window for the Superduke. For the record, my application is a 2008 SD, stock exhaust.

BTW - whoever asked, my '08 came with a 17.0 Rear, and 0.95 kg/mm front (stock). I think it was the same for US-model in 2007 as well. On that note, these rates seem to follow all manufacturers' contemporary practice on sportbikes, to prevent the liability of inadvertent wheelie-ing, rear wheel spin, and abrupt turn-in. This translates into too soft out back, and too-stiff-for-most in front.

I think RT's "calculator" is WAY off. WAY WAY OFF. I am running a 19.7 kg/mm, and RT's calculator indicates I should use a 18.4 kg/mm - and I'm NOT convinced that the 19.7kg/mm is enough rear spring! Anyone have a 21.5 Kg/mm they could loan/rent me? j/k. I can state that putting on an R-model spring was definitely not enough. Maybe if I go to some Akra cans, it will behave a little less unruly. The thermonuclear reactor stock exhaust is a lot of extra mass cantilevered out there ...

On the front, RT's calculator suggests a 0.74 kg/mm - :lol: That's just plain hysterical. What adds to the humor of this value, is what I perceive to be the significant (good!) forward weight bias of the SD.

Based on the weight of the bike + my weight + gear, rake/trail, etc. .95 kg/mm - I'm fairly certain (and perceive) - is about the minimum I would want to use. If I put in what I dial up for a sportbike for front preload - I can't feel the front tyre at all, and the perception at the bars is that its pushing. Add too much front rebound, and it feels like the bike wants to tuck in. Sketchy. I am a late braking fool (often, all the way to the apex), and appreciate knowing exactly what my tyre is doing through corners. So, I don't mind running a little soft(er) up front.

RT also notes "Spring guide must be machined to fit in the ID of the RT Springs" - ? Are they kidding?

Don't get me wrong, when flogging the bike at the track, all feels and behaves OK. But around town, with the SD's characteristic throttle uncertainty thrown in (that is, when I'm not winding the piss out of it all the time and everywhere), the bronc likes to buck and seesaw through corners like there's no tomorrow. I really question the valving of the shock and forks.

As we have not a single WP street bike suspension specialist in the US (please correct me if I'm wrong - and I want to be wrong about this - I went so far as to contact WP in Austria for a reference), it would be great if one of you UK WP suspension gurus could chime in and create a spring rate chart for front and rear, applicable for both street and race, a function of rider weight.

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MrZ32
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Re: spring rate

Postby MrZ32 » Sat Jun 25, 2011 12:47 am

what you have to remember is that the SD has a lot more suspension travel than a normal sportbike so softer suspension can be utilised for the bumpier b/c grade roads.

I dont know how heavy you are... but if a 19kg spring is not enough im assuming that you are no light weight.

The rear spring calcs on the site are pretty good however I agree, the front springs are way off and should be disregarded.
08 SD, WP Dampener, 'Suspension Improvements" tuned sus (springs, valves, shim stacks ), KTM cowl, R&G carbon covers, Termi Pipes (from a duc 998), Grim990 Airbox, breather mod, SAS plates, tuneECU PDI tune, HM QS, JTM VS & DVS

Japanviking
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Re: spring rate

Postby Japanviking » Sat Jun 30, 2012 8:41 am

Revisiting this topic as I have just received my Gold valve kit from Racetech.
I have changed the rear spring on my 2009 SDR to a 20.0kg to reach correct sag numbers. Up front the stock 0.95(?) seemed to be enough.
Entering my numbers into the racetech calculator gives me a recommended spring rate of 0.74. This is clearly wrong.

Bike is at the dealer now for the very expense bi yearly inspection here in Japan. Can't wait to rip the forks apart and install the new valves when I get it back.
KTM SDR 09 (Tokyo)
BMW R1200GS 06 (Tokyo)
Aprilia RSV Factory 05 (Sweden)

cheesie
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Re: spring rate

Postby cheesie » Sat Jun 30, 2012 7:30 pm

I am 16 stone and needed a 200nm spring for my sdr and have found the front oem jobs measure up ok

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SDNerd
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Re: spring rate

Postby SDNerd » Mon Jul 02, 2012 4:24 pm

cheesie wrote:I am 16 stone and needed a 200nm spring for my sdr and have found the front oem jobs measure up ok


16 stone with or w/o gear?

If w/o gear, the 9.5 N/mm fronts are too soft. Arguably too soft for that weight even with gear ... Was this bike owned by someone else before you? Or an ex "battle bike"? If it's how you like it, it's how you like it - but if there are still the 9.5s in the tubes (meaning: they weren't changed out) - you probably aren't getting the best spring "balance" that you can.

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Re: spring rate

Postby cheesie » Mon Jul 02, 2012 9:36 pm

it has standard sdr forks and for some reason they measure up fine, in fact the forks that it came with measured up the same, I am 16 stone in me pants

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Re: spring rate

Postby LeDuc » Sat Mar 26, 2016 4:15 am

MrZ32 wrote:I am running 0.85's in the front and a 16kg in the rear... I am around 78kg with gear on... Seems about right however soul have been happy with 0.9 in the front too.
Indy yours are 0.9 and 16 for front and rear... Prob fine but .9 & 17 would work better for you as you're a bit heavier than me


I know this is super old post but I find myself in a situation similar to yours, I am 70kgs and hesitate between 0.9 and 0.85. I would love to hear about your experience.

Cheers


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