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What about fork sag?


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There is so much written about rear shock sag settings, but almost nothing about the forks. I've been trying desperately to get my forks dialed in without much luck. I re-sprung both the forks and shock based on the race tech spring calculator, and while the rear shock is dead on, the forks just don't do it. They are anything but plush and they get real harsh at the end of their stroke. Right now I have the compression damping screws all the way soft, and the rebound damping two clicks out from their softest setting. This set-up is as good as I can get for desert riding. I see lots of whooped out trails, and the whoops are (pun intended) whooping my a$$. The rear shock sags about 105mm with me on the bike, but the forks only sag about 37mm. Is this part of the problem? My owner's manual doesn't give a spec for fork sag, but it does say that it should sag evenly with the rear. Are my springs too stiff? I'm running a 5W fork oil.

Lou

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Its not actually possible to set 'SAG' for your forks. No adjustment

it is actually, by way of spring preload and/or heavier rate springs;some open cart wp's even have externally adjustable preload. no more than 1/3 of travel should be used .... rider standing on bike w/gear. idk about what would be too little?

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My bike has Showa cartridge forks, and there are actually two sets of springs in each fork. The long spring is in the lower part of the fork, and then there is a short spring, I'd guess 6" or so, at the top of the fork cartridge, just below the fork cap. I wonder how the little spring fits into the equation? I've seen them for sale at motosport.com, and there are different rates available. I wonder if my plushness answer can be found there?

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it is actually, by way of spring preload and/or heavier rate springs;some open cart wp's even have externally adjustable preload. no more than 1/3 of travel should be used .... rider standing on bike w/gear. idk about what would be too little?

Understand the heavier springs, but how do you preload the springs in the front?

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Understand the heavier springs, but how do you preload the springs in the front?

almost all forks are adjustable with preload washers(size is dependant on fork type) that go between the spring and perch or some down under the spring,alot of older open bath forks had a piece of pipe that adjusted preload by varying its length!

yes lou, the ics (the little springs you refer to) can plushen the ride and does affect overall spring rate so a lighter rate ics in turn will make the front dive in easier,but the statement of i've got the clickers all the way soft could mean that your riding too low in the stroke which would contribute to the harshness your feeling,try going to the middle ground of 12c/12r and 320ml of oil in the outers and work from there.

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first mistake you made was using race-tech spring calculator; they are always too light. use Mx-Tech or call the guys at Cannon Race Craft. Get the proper springs....

Always? As mentioned earlier race tech calc showed 5.2 for me and I had to end up going with 5.0 to get the sags correct. I can thank MOG for looking at all my info and suggesting the correct spring rate.

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ncmountainman,

Thanks for the advice. It is the most helpful that I've gotten.

You know, if it weren't so expensive, customising suspension could actually be fun. ­čĹŹ

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Always? As mentioned earlier race tech calc showed 5.2 for me and I had to end up going with 5.0 to get the sags correct. I can thank MOG for looking at all my info and suggesting the correct spring rate.

yes, but if I remember correctly, didn't you do valving too...

and from what I've read and experienced, more times than not, do they get it wrong...

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Anybody else have some guidance on this subject?

Repeatability is the key. You have to be able to measure the sag several times, and have it come out pretty close to the same to be worthwhile. Here's one way we do it:

- Measure the bikes static sag. Take the bike off the stand, pull the front brake and compress the forks, and then slowly let the front come up. Next, take a marker and mark the fork tube at the dust seal. Next we tap the front wheel with a rubber mallet. The bike rises, but will eventually settle on one spot. Mark that with a marker, put the bike on the stand and measure.

Again, the key is repeatability. You should be able to do this 5 times, and be within a couple mm. If you can't be within a couple mm, it probably ain't worth doing.

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