Measuring spring rates - Wrist Twisters
 
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post #1 of 8 Old 02-02-2015, 06:19 AM Thread Starter
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Measuring spring rates

My FG series Ohlins forks came with unmarked springs. A little research showed that this particular fork model (FG8901) should have 0.95 kg/mm springs. Also from what I found, Ohlins does not mark their 0.95 springs that come already assembled in forks. However they do mark their 1kg spring with 2 lines and 1.05kg with 3.

Example of 1.0 kg/mm spring (disregard spring on the left, it's origin is unknown)




Most of us not as "cool" as LDH and don't have daily access to Dan Kyle toys therefore one needs to improvise:

here is what I did to confirm that my 0.95kg/mm spring are indeed 0.95.
As you already know, any springs (even linear type springs) are progressive to a certain extend). Therefore to get somewhat accurate measurement, it has to have some initial preload. For my experiment, I decided to load it just past typical Free sag range (5-10mm.)
Here are my numbers:
Spring length at rest - 240mm
Spring length under 11.34kg - 228mm

Rate= weight / length difference or 11.34/12 = 0.945 kg/mm

Finally got some use out of these hand weights
Attachment 94841

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post #2 of 8 Old 02-02-2015, 06:40 AM
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Very clever! Never thought of using free weights for that. Of course I usually test rear springs, meaning I'd need about 500 pounds of weights at minimum to get a meaningful result.

Rob

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On the other hand, if it has not been done never assume it is impossible to do it.
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post #3 of 8 Old 02-02-2015, 06:49 AM Thread Starter
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Quote:
Originally Posted by robtharalson View Post
Very clever! Never thought of using free weights for that. Of course I usually test rear springs, meaning I'd need about 500 pounds of weights at minimum to get a meaningful result.

Rob
That's what gym membership is for. All kinds of weights there

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post #4 of 8 Old 02-02-2015, 07:41 AM Thread Starter
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hmm, not sure why mobile app doesn't show attached pics....

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post #5 of 8 Old 02-02-2015, 08:26 AM
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Quote:
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hmm, not sure why mobile app doesn't show attached pics....
I see them with no problem.

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post #6 of 8 Old 02-02-2015, 09:15 AM
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I see them with no problem.
All I see is a motorcycle.com logo

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post #7 of 8 Old 02-02-2015, 09:24 AM
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All I see is a motorcycle.com logo
Damnit!..... Oh wait.....

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post #8 of 8 Old 02-02-2015, 09:27 AM
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Quote:
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All I see is a motorcycle.com logo
Want some cheese with that whine?

image-2828869055.jpg

:P

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