ohlins rear shock spring recomendations

Discussion in 'GS Boxers' started by bergerkingman, Jan 13, 2008.

  1. bergerkingman

    bergerkingman Adventurer

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    1200gs with olins from Dan Kyle Racing. Am about to send in the rear shock for a second time. The first time we determined I needed a softer spring. I did not see much if any difference. The spring I have is a 00698-64/160 L476. Searching around I see one rider has a 59/150/257 and another has a 39/110 L213. The problem is almost no sag when riding alone (15mm). The rear wheel tries to come off the ground. Fully loaded is about wright with no pre-load adjustment put in. With suit on I weigh about 210. I need a heads up before I call Dan this time.
    #1
  2. MOTOCYCLISMO

    MOTOCYCLISMO Adventurer

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    I feel your pain!! You are right, the spring supplied for the standard GS is way to stiff. I'm 170lbs and the 130 sping allows for almost no sag statically. I took my shock to Dan so I could reduce the pre load(you have to dismantle it to do so). Even with the preload backed all the way off its still to stiff. Get the next lowest spring rate! Dan is wrong about this issue.I've reduced the rebound damping to acceptable levels and it helped. Oddly my 1200GSA with Olins is perfect but I have a more sophisticated shock on it.
    #2
  3. rideLD

    rideLD The further the better!

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    Here is what I know. Assuming the Ohlins spring rates have stayed the same since 2005. These numbers are for the standard GS and not the adventure.

    -Standard front spring rate good for about 170-210b rider + gear
    -Standard Rear spring rate good for about 200-240lb rider + gear
    -One spring rate lighter than standard on the front good for about 140-180 rider + gear
    -One spring rate lighter than standard on rear good for about 170-210lb rider + gear
    -One spring rate heavier than standard on front good for about 200-240lb rider + gear
    -One spring rate heavier than standard on rear good for about 230-270lb rider + gear

    Some people get all confused about if they should select a spring rate to encompass your passenger as well and the conventional wisdom is that you should not because you want you bike to handle best when ridden solo. You normally ride slower and more conservative when you have a passenger and therefore do not need perfect sag rate.

    When I refer to gear I am talking about 30-50 lbs average which includes your riding gear, hard cases, and a light load in them. If you never run hard cases or carry gear you will want to subtract 30-50lbs from your rider weight.

    The Ohlins standard front spring for the R1200GS is 01096-10 / 52 L404 which is a 5.3 KG spring rate.
    The Ohlins standard rear spring for the R1200GS is 00698-54 / 140 L065 which is 14.27KG

    The number you mention (00698-64/160 L476) is a 16KG rear spring which is one spring rate up from standard for the R1200GS. Way too much spring for your 210lbs as you already know.


    These numbers are very approximate but are based on my actual experience setting proper sag on R1200GS's. YMMV
    #3
    Rockred and hangontight like this.
  4. dwf

    dwf 2007 R1200GS Adventure

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    What weight spring do you have on your 1200GSA?

    #4
  5. BMW-K

    BMW-K F800GS FTW!

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    It all depends on preferences. I am 195# and use a +2 rated rear spring.

    And it still feels a bit soft!
    #5
  6. rideLD

    rideLD The further the better!

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    Actually it is all very scientific. There is an ideal sag number range (25-33% on most bikes) that you must achieve for the bike to handle the way it is designed to.
    #6
  7. fooey

    fooey Live Bullet

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    I have the 59/150/257, BUT... I also have the big$$$ shock adjustable for length, compression and rebound so that # may not relate to your shock. I am 210 geared up. My sag is 57mm loaded so close enough! Just get the standard rate LD mentions for your shock and it should be good. :1drink Maybe give it some time to settle in too. Later...:1drink
    #7
  8. rideLD

    rideLD The further the better!

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    Thats a great point. The spring will break in and you will end up with 5-10% more sag once the spring relaxes.
    #8
  9. RoundTrip

    RoundTrip Unintentional deerslayer Supporter

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    Which, if it was figured correctly for normal load, will come out to approx 25-30% total travel sag with your butt on it.

    -jeff
    #9
  10. jimbucajoe

    jimbucajoe n00b

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    Does anyone know the difference between part # (01096-11/54 L206) vs (01096-11/54 L353) I have a opition to buy frt ohlins shock for my 1150GSA but need clarification on the correct spring choice? Thanks Joe
    #10
  11. Motowalt

    Motowalt Been here awhile

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    Give Dan Kyle Racing a call...
    He can tell you straight up...
    #11
  12. Mr Head

    Mr Head Adventure Hippie Supporter

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  13. Mr Head

    Mr Head Adventure Hippie Supporter

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    Some additional thoughts,
    The number we change is the Force due to that rate and preload and sag added, resulting in some big force number. As in the following:

    F=kdx
    Where F = the resulting force due to preload and sag together.
    "dx" is the change in the distance from the free length the spring to compressed.

    "k" is the spring rate from above, that 571 lbf/in of deflection.

    Also in a steel compression spring you are going to be hard pressed to change this spring rate. That is unless the spring somehow loses its temper, or is compressed beyond its elastic limit. About the only way I guess to do this would be to compress the springs to coil-bind, (coils compressed such that they touch), and then leave them there for a very long time. Or both that and add some heat, (that old lowering the car trick form the fifties).
    Still this will simply shorten the overall length of the spring the rate is constant, (Unless you use heat, then all bets are off which is why that method of dropping a car was a bit hit or miss)...
    Or for all practical purposes a constant. There is a bit of non-linerarity but the affects of that are small, thrid order or so, has to do with damping in the spring itself. If I remember correctly It has been a while since I messed with this stuff.

    What feel like spring rate change in a coil-over shock system is not the spring rate changing but more likely the compression damping changing. This rate can and does change along with the rebound damping rate over use and time as these are a function of the states of the oil, seals, and charging gas.

    It should be fairly simple calculation to find the close-enough spring rate as a function of sag.

    Fun too. :huh

    I think it will require some paper, a pencil, camera measuring tape, then a computer and some alcohol. You know to keep everything clean.:freaky


    So, is everyone ready for their homework?

    Remember to show your work, and remember units are important!:wink:
    #13
  14. davidgibson999

    davidgibson999 Been here awhile

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    I've just purchased a set of ohlins for my 2005 GS12. Dealer says they are standard springs but the markings are different.
    Mine read:
    01096-10/52 L316 (Front)
    000698-54/140 L266 (rear)
    Mine are UK spec shocks so maybe they use a different coding system?
    Can anyone tell me what weight of rider these are ideal for and whether or not they are the standard spring height?

    I weigh approx 80 kg with my gear on.
    #14
  15. grantsdad

    grantsdad Been here awhile

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    I have never measured the sag on my bike. In 2009 I weighed 195 lbs. Today I weigh 220 without a helmet. 6'3" tall. The guys at Ted Porter's BeemerShop are recommending a "170" rear spring for my '07 R1200GS. It has BMW adventure cases on it at all times. Empty when I commute they weigh 15 lbs each and 25 lbs each when I'm camping. When camping I also carry a 16 lb duffle. I know nothing about suspension tuning. I've ridden the bike 50K miles with a "150" spring. In your collective opinion, will the 170 be too stiff?
    #15
  16. 177in70s

    177in70s Adventurer

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    Two Up?
    I see a rear spring rate of 130 N/mm for Ohlins BM670 Rear Shock for the 1200 GS (wethead) at https://www.ohlins.com/app/uploads/world/2018/08/MI_BM670_3_x.pdf. A GS has about 7 inches of rear travel. My '85 K100RS has about 4" of rear travel as does the wethead 1200 RT. I see the Ohlins BM504 Rear Shock for the 1200 RT has a spring rate of 170N/mm.

    Am I correct to think that a sudden road bump that makes my wife wince will have to be 170/130 = 1.307 = 31% bigger under the GS to feel like one on the RT ???????????
    (Assuming neither bump makes the rear bottom out).


    Years ago I took my wife out locally on an '88 Honda NX250, a super soft dual sport, she never had felt such a soft ride over familiar bumps.
    Don't softer springs add comfort if you can preload correctly so as not bottom out and the spring rate still allows much of your travel ??????????


    To get a soft 2 up ride and to take 2 up camping gear strapped on, I'm thinking wethead GS with as soft a rear spring as we can "get away with," most likely stock.

    Looking forward to your comments and feedback.

    From Phila, K100RS w 197,000 mi. '90 K75S 55k, '03 KTM EXC 250 Four 150 Hrs, 88 NX250 10k,
    #16
  17. roadrage

    roadrage Long timer Supporter

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    I'm not riding a 1200, but Ohlins on my 1150 with Jesse bags and a higher rate rear spring is still too damned soft even with preload cranked up. Add a passenger and it's worse. I'm 200lbs without gear. Day to day with empty Jesses the back is soft and my head light is bouncing up and down at ever bump. I'm sure people ahead of me think I'm constantly flashing my high beams... Maybe I need more compression damping, I run the rebound pretty loose to avoid pack.
    #17