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post #31 of 36 Old 11-07-2012, 06:37 PM
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I found the thread on rider sag where we went over preload spacer length. It's on page 5 post #46. that should get you into the ballpark.
sag set on stock suspension

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post #32 of 36 Old 11-09-2012, 01:36 AM
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Quote:
Originally Posted by Glitch View Post
FRONT FORK SPRINGS
Recommended Fork Spring Rate: 0.782 kg/mm (use closest available)
Stock Fork Spring Rate: .490 kg/mm(stock)

so i should have almost double the front rate than stock provides? hence the "squishy"?
if those numbers came from racetech, then .782kg are rates for their line of linear springs. cbr stock fork springs are not linear, they are progressive springs. a progressive wound spring normaly has two spring rates , one for the top set of coils and one for the other set of coils. racetech didn't post the other rate. thats why their spring number shows a rate 2x stiffer than stock. but in reality, they are showing only the initial rate of the stock progressive spring. if they were to show the final rate, it would probably be 0.74-0.76kg/mm, not that far off from what they're recommending for ur weight.

not trying to discourage you from buying new springs, but at your 155lb light weight, you should be ok w/ the stock springs.
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post #33 of 36 Old 11-09-2012, 02:35 AM
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the stock spring is so weak that i believe that the secondary winding on the spring really only acts as a bump stop as opposed to a progressive rate as such. with the racetech spring, you may only get a linear rate but you have it for the whole of the fork travel. whereas, with the stock spring, it is so weak that you have to compress most of its travel to get the rider sag set properly. if you look at my install thread you will see a picture comparing both springs. you can see that the stock spring is a fair bit longer than the aftermarket one. in order to get the rider sag into the correct range you need a preload spacer of roughly the same length for both springs. I mentioned in one of the threads that the stock spring rate is about 0.49 kg/mm. my springs are 0.80 kg/mm and I weigh about 180 lbs. i thought i would try and see, according to racetech's site, what weight rider would need the stock spring rate. 30 lbs was the lowest rider weight i could input into their program and the recommended spring weight was still higher than 0.49 kg/mm.

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post #34 of 36 Old 11-09-2012, 03:07 PM Thread Starter
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Interesting... hmmm would a dirt bikes sag be set up similar to a street bikes? Im thinking not but the principle should be the same right? If so ill ask my buds dad to help me figure it out... i just cant seem to wrap my mind around it. I get the measurement part, but everything else is a big question mark.

So i get my "sag number" cool.... then what? Lol. I have to do something to figure it out and i have no idea what to do.

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post #35 of 36 Old 11-09-2012, 03:46 PM
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First you determine what spring you want to use. Say, for ease, you use the stock spring. Rider sag for this bike is in the 30 - 35 mm range for road riding. Which is to say, when you get on your bike, the forks should compress by 30 - 35 mm. I think that the rider sag on the stock forks, with an allowance for differing rider weights, is about 50mm +/-. This means you need to change out the preload spacer, that is in the forks, for ones that are at least 20mm longer to get you into the ballpark. The stock preload spacers are about 102mm so I would say start with new spacers cut to 130mm. Put them in and then check your rider sag. If the bike drops more than 30-35mm, with you on it, you need to add that difference to new spacers. If the bike drops less than 30-35mm, you need to subtract that difference from the spacers.

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post #36 of 36 Old 11-12-2012, 07:58 AM Thread Starter
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Roger! I will check that as soon as its not raining

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