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Setting the rear spring

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My mate attacked my bike last weekend as he thought my rear looked wrong and was way too tight, this is a distinct possibility as the mate I bought my bike from is very tall :thumbsup: so he could well have wound the spring up a bit.

Anyway I did the measurement today and they are as below,

On the lift stand 60cm

Under bikes own weight 56cm

With me on the bike 51cm

I was in normal clothes (not on full gear with back pack) so I'm thinking the race sag will be about right now?

The only issue following this adjustment was the steering felt a little low rider/cruise style so I dropped the yokes a little today (maybe 6mm) and it feels more like normal again.

So what's your opinion on my rear spring - is it now set-up okay and is it the right spring for me?

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so your saying your static sag is 40mm (60cm or 600mm - 56cm or 560mm)

and your rider sag is is 90mm (600mm - 510mm)

accepted wisdom says 25mm/100mm (static / rider sag)

your readings suggest your spring is too hard for your weight

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The spring is the standard one, which I was lead to believe (from reading posts on here) was generally too soft.

I weight 74 kg's in the buff (163 pounds) so I'm guessing maybe up to 80 Kg's in full bike gear (176 pounds).

what weight is the standard E spring rated for?

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I think you should measure it again, you numbers are not really adding up.

Your static sag contradicts your race sag for your weight.

You need an assistant to do the measuring while your in your normal riding position.

Pays to bounce the bike up and down a couple of times, let it settle, then measure.

It's also good to take three measurements then average them out to allow for stiction.

Use mm's to measure, it's more indicative of the effects when adding or reducing preload. :thumbsup:

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Just checked again.

Different tape (mm only), on flatter ground, with suspension bouncing being done.

Rear wheel off ground - 583mm

bike on own weight - 542mm

Me on bike (feet on ground) - 490mm

I realise now I should have had me feet up but I was just using feet for balance - not much weight, tip toes..

Race sag of 93mm

standard sag of 41mm

Ah, that means the spring is too light doesn't it?

I really need a higher rate spring?

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Just checked again.

Different tape (mm only), on flatter ground, with suspension bouncing being done.

Rear wheel off ground - 583mm

bike on own weight - 542mm

Me on bike (feet on ground) - 490mm

I realise now I should have had me feet up but I was just using feet for balance - not much weight, tip toes..

Race sag of 93mm

standard sag of 41mm

Ah, that means the spring is too light doesn't it?

I really need a higher rate spring?

You meant to have all your riding gear on, your feet on the pegs in your normal riding position.

Use a wall or something to balance your self:bonk:

Then do your rider sag measurement.

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Just checked again.

Different tape (mm only), on flatter ground, with suspension bouncing being done.

Rear wheel off ground - 583mm

bike on own weight - 542mm

Me on bike (feet on ground) - 490mm

I realise now I should have had me feet up but I was just using feet for balance - not much weight, tip toes..

Race sag of 93mm

standard sag of 41mm

Ah, that means the spring is too light doesn't it?

I really need a higher rate spring?

Wind the preload up to 25mm static sag, put your gear on including stuff like a Camelbak if you normally use one, get your feet off the ground and measure again. Odds are the spring is a little stiff, but only by a nats and that what you have is quite workable.

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Wind the preload up to 25mm static sag, put your gear on including stuff like a Camelbak if you normally use one, get your feet off the ground and measure again. Odds are the spring is a little stiff, but only by a nats and that what you have is quite workable.

still say it'll be too hard

reducing the static sag to 25mm from 41 is 16mm less

rider sag of 93mm with 15/16mm less is <80mm which means spring is too hard

E model springs re softer, as the S model has a harder spring to cope with two up riding

think S model is 5.5kg/mm and E model is 5.3kg/mm

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still say it'll be too hard

reducing the static sag to 25mm from 41 is 16mm less

rider sag of 93mm with 15/16mm less is <80mm which means spring is too hard

Yes & no.

If by winding down my adjuster ring on to the spring all I'm doing is effectively winding up the static sag, then yes, it will be 16mm off both measurements.

However, I don't think it works like that - it's pre-loading isn't it?

So meaning that it's adjusting the load rating of the spring at that compression to some extent.

Adjusting it to take 16mm of the static sag will take more than 16mm off the race sag - or am I miss-understanding it?

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FFS, 16 mm of preload does not directly give you 16 mm less of race sag.

Untill you get your feet on the pegs and some accurate sag figures it's all conjecture.

Just a small point but no one is suggesting that 16mm of pre-load equals 16mm of sag.

I then suggested that if by adjusting the static sag by 16mm the race sag also moved by 16mm then I would agree that my spring is too hard but then I went on to say I didn't believe it worked like that.

Feet on the pegs - just how much weight do you guys think feet of the pegs is going to add?

Is it more that when you have your feet on the pegs and are stood that your weight is then central on the bike?

Just for information my feet were just only just tickling the floor, slight contact - just to aid balance, hardly load baring. I suppose my centre of mass was further back than the pegs though so that may well have loaded the rear more than it should have.

I will drag the bike out again at the weekend and repeat the measurement once more.:thumbsup:

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Just a small point but no one is suggesting that 16mm of pre-load equals 16mm of sag.

Feet on the pegs - just how much weight do you guys think feet of the pegs is going to add?

I will drag the bike out again at the weekend and repeat the measurement once more.:thumbsup:

My bad after I posted I reread and saw my error, sorry.

Where your feet and body are on the bike can make measurable difference.

This is why if you stand alot, sag is measured while your standing.

Regardless of sitting or standing you need your feet on pegs and in your normal riding position before we know how to advise:thumbsup:

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okay, I have re-done the measure with me stood on the pegs.

Rear wheel off ground - 583mm

bike on own weight - 542mm

Me on bike (feet on pegs, stood up) - 485mm

It made 5mm difference.

So that's got my race sag at 98mm - that's where it should be shouldn't it?

So to get my static sag up I need a stronger spring I take it?

Would an S spring do the trick or should I be aiming for firmer?

..or should I just wind up the preload to aim for a happy middle ground, maybe take the race sag down to 88mm and see where the static sag lands then?

Cheers, Rich.

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As indicated by GuyGraham, your spring is slightly too stiff. It is certainly not too soft. Think of a 250 lb rider on your bike with the current spring. If he adjusts the preload to give the correct race sag there will be a lot of preload. This extra preload results in very little (or no) static sag.

In practical terms your spring should be OK.

Ian

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Yes & no.

If by winding down my adjuster ring on to the spring all I'm doing is effectively winding up the static sag, then yes, it will be 16mm off both measurements.

However, I don't think it works like that - it's pre-loading isn't it?

So meaning that it's adjusting the load rating of the spring at that compression to some extent.

Adjusting it to take 16mm of the static sag will take more than 16mm off the race sag - or am I miss-understanding it?

Yes, your are mis-understanding it

Altering the preload merely raises the bike up and down, and DOES NOT alter the spring rate

The static and rider sag will increase or decrease by the same amount roughly, as the rising rate linkage can alter things slightly, but not as much as you think

okay, I have re-done the measure with me stood on the pegs.

Rear wheel off ground - 583mm

bike on own weight - 542mm

Me on bike (feet on pegs, stood up) - 485mm

It made 5mm difference.

So that's got my race sag at 98mm - that's where it should be shouldn't it?

So to get my static sag up I need a stronger spring I take it?

Would an S spring do the trick or should I be aiming for firmer?

..or should I just wind up the preload to aim for a happy middle ground, maybe take the race sag down to 88mm and see where the static sag lands then?

Cheers, Rich.

no you'll need a softer spring to get your static sag down to 25mm and maintain the 98mm rider sag

Your spring only compresses 57mm (98mm - 41mm) under your weight - you want it to compress 75mm hence the current spring is too hard

Am I reading this right, that you did the measurements with you stood up on the pegs?

You should be in your normal seated position

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Yes, your are mis-understanding it

Altering the preload merely raises the bike up and down, and DOES NOT alter the spring rate

The static and rider sag will increase or decrease by the same amount roughly, as the rising rate linkage can alter things slightly, but not as much as you think

This is what I really don't understand. If the system had no end stops then I agree 100%, but the system does have an end stop. The spring is still under compression isn't it even when the shock is at it's furthest travel, so adjusting the pre-load will have a slightly different effect on the suspension throughout it range of movement..

So tightening it to make the static sag 5mm less might make the race sag 8mm less, if you see what I mean..

Have I understood correctly so far guys?:busted:

Edited by DrzDick

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no you'll need a softer spring to get your static sag down to 25mm and maintain the 98mm rider sag

Your spring only compresses 57mm (98mm - 41mm) under your weight - you want it to compress 75mm hence the current spring is too hard

This is the bit I can't understand but I do see where your going with it..

Rear wheel off ground - 583mm

bike on own weight - 542mm static sag is 41mm

Me on bike (feet on pegs, stood up) - 485mm race sag is 98

The way I see it, if I were to get a harder spring it would be able to hold the bike up better while still allowing correct race sag.

..or is it that with a softer spring I would be able to put more preload on the get the right static sag whilst still achieving the 95mm race sag?

Also - yes. I stand more than I sit so I was advised on this thread to check setting whilst stood on the pegs.:busted:

Edited by DrzDick

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The way I see it, if I were to get a harder spring it would be able to hold the bike up better while still allowing correct race sag.

..or is it that with a softer spring I would be able to put more preload on the get the right static sag whilst still achieving the 95mm race sag?

The latter. :busted:

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Cool - :busted:

I can live with the spring being too hard. I'm planning a trip next year so will have the bike loaded up a little - should be about right for that then.:bonk:

In the mean time I'll put a little preload on the spring to try and get back a little static sag at the cost of a few mm's of race sag.:busted:

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