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Dirt Bike Sag Question

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I just finished adjusting the rear sag on my Yz450f, but I'm not sure about one thing. I lowered the bike a few inches and I noticed that the spring feels loose when the bike is on the stand. I'm able to freely move the spring around when the bike is on the stand, yet when the bike is off the stand the spring doesn't move at all. I now feel comfortable, but did I lower the bike too much? Is this normal? Should I raise the bike to add some tension in the spring? Thanks for any advice.

Edited by CallMeAnsel

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When the wheels are off the ground, the spring still needs to have some tension on it all the time by at least a few millimeters.  If you need to lower the rear more and the spring becomes loose, then you need a softer spring.  

How much do you weigh?

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Lowering your bike by backing off your spring preload is not a good way to lower your bike and will cause handling issues. You won't have enough traction on the front tire and it won't corner well.

You should set your race sag to be around 105 mm. I'm not sure what works best on a YZ 450 as I've never owned one of those but it will be close. Static sag should be between 25-35mm and you will have the right spring rate.

To really lower your bike the best way is to have a suspension tuner internally lower your suspension. Second would be to get a lowering link and possibly cut your seat foam down or lower your sub frame.

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You def need a lighter spring.  I weigh 145 and am 5'10" and don't feel the absolute need to lower my bikes, and I had a '07 YZ450 for a little bit.  It did need lighter springs though for sure.  I think they're targeted at 180+ riders. 

Easy answer- go onto Racetech's website and use their suspension calculator for both front and rear springs, as you'll probably need both sides lighter, not just the rear.   Then just buy both and start from there.  

What happens when you "lower" a bike by loosening the preload collar is that when the suspension extends fully(in the air, if the tire drops into a hole, hard braking, etc.) is that the spring could come off the perches and damage the shock.  Like I said above, the spring must have at least a few mm's of tension on it at all times, this includes when the wheels are completely off the ground on the stand.  

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