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Race sag problem

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Hi, didn't know where to go to introduce myself but im Dan, England

Basically i've been trying to get my race sag between 90-100mm, as thats what it says it should be at

But every time i move the damn preload the measurement stays the same; i started at 510mm static sag, it went to 450mm when i sat on it with all my gear, so i kept whacking it but it would always stay 60mm behind, im now on 560mm static and it on 500mm when i sit, my static to on the stand difference is 20mm so within the recomended measurement of 15-20mm

I weigh 15 stone, am a intermediate rider and my spring rates are .46 in the front and .56 on the rear

The shock and everything has been serviced and the linkages greased, but to be honest i dont even know what spring rates i should have

If anyone has any ideas, much appreciated

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Those numbers are crazy, what kind of machine is this? How are you measuring rider sag? How are you measuring static sag?

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Sorry yeh it says 15-30 not 20, what do you mean 'rider is usually started'? Cheers

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Sorry, I meant that 100-105 is a "base" setting. A guideline setting to start with. Good luck.

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Your not setting it with the bike on the stand ??? As your first number is changing and that's the fully unloaded length which doesn't change even with altering the spring length

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with the bike sat on the stand you should be getting around 620mm (from the top right corner of the swing arm to a bolt in the fender that sticks out. this is your base setting and when you take the bike off the stand you should be getting around 30mm of sag. (590mm) and when you sit on the bike it should be 100-105mm sag or (520-515mm) from the bike being sat on the stand.

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Since he says both numbers are changing, it's my guess that he is measuring from bike on the ground without rider (static sag) to bike on the ground with rider (race sag).  The difference between those two will always be the same, until you get to a very high preload.

 

OP, you need to measure race sag from bike off the ground (fully extended) to on the ground with rider.  The bike off the ground measurement should never change, because the shock is fully extended at that point and the spring has no effect (you can argue that a lot of preload will slightly change the compression of the top out spring, but that's negligible).

 

With 60 mm of change from static to race, your spring might be a bit on the stiff side, but I'd get both sags dialed and see where it ends up.

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When its on the stand its 580mm

When it sits on its own its 560mm

When i sit on it with full gear its 500mm

I have used up all of the thread, even if i go to the recommended 10-20mm of thread showing (ive been told this by mechanic at track) the rear sits really low and the static, without me or stand, to the stand measurement is something silly

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When its on the stand its 580mm

When it sits on its own its 560mm

When i sit on it with full gear its 500mm

I have used up all of the thread, even if i go to the recommended 10-20mm of thread showing (ive been told this by mechanic at track) the rear sits really low and the static, without me or stand, to the stand measurement is something silly

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I think we are still having a communication problem that is confusing things. Secondly I have always been told to START with a setting that achieves a 100-105 mm rider sag. Then measure static sag. I would do that FIRST and then proceed. Just forget the threads on the shock for this test. Get the 100-105 and let us know what the static is.

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You have too much preload on the spring. it needs tension off so that:

 

it is at 545mm when the bike is sat on the ground

 

this should then give you the desired rider sag of 105mm or 475mm whichever way you look at it.

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Sounds like your going the wrong way , like previous post says you need to take tension off the spring

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Trust me, i started from the very top of the thread and reached the bottom with the race sag staying at 60mm all the way, the only reason i left it at the bottom of the thread is because the sag from the stand to static was within the 15-30mm margin

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If the race sag is staying the same with such a huge pre load change something is totally wacky. I think you need to seek a respected experienced rider/tuner to get a fresh look at things.  This just does not make sense.

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Tell me about it, ive been making do for the past 6 months!! Cant believe ive never had my suspension set-up right

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Are you sure there is nothing catching or binding in your linkage/swing arm?

This is quite a side note but I also like to set sag with the clickers on softest ( just my personal way of doing it ).

Just curious, do you have someone helping you set sag?

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Trust me, i started from the very top of the thread and reached the bottom with the race sag staying at 60mm all the way, the only reason i left it at the bottom of the thread is because the sag from the stand to static was within the 15-30mm margin

 

I think you're measuring race sag wrong.  You posted this:

 

When its on the stand its 580mm

When it sits on its own its 560mm

When i sit on it with full gear its 500mm

 

With these numbers, the race gas is 80 mm, not 60 mm.

 

I suspect that you are trying to calculate the race sag by subtracting the measurement with rider from the measurement without rider.  That measurement is NOT the race sag, and it's never going to change by adjusting preload (see caveats in my previous post).

 

Based on the numbers above, you have 20 mm of static sag (580-560) and 80 mm of race sag (580-500).  You want to get to 100 mm of race sag, so you need to take about 6-8 mm of preload off the spring (assuming 3:1 linkage ratio, should get you close).

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Are you sure there is nothing catching or binding in your linkage/swing arm?

This is quite a side note but I also like to set sag with the clickers on softest ( just my personal way of doing it ).

Just curious, do you have someone helping you set sag?

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