Thinking about going up to 20W fork oil (with my progressive springs)

[Guest]

I've noticed, as I get things sorted out & drive more assertively, that as I come to a complete stop, I'm getting a "second bounce", as the front fork settles. I've put progressive suspension springs & 10W betray fork oil in the GK's forks.
If I had it to do over, I would have gone with straight rate Sonic springs. Sorry.
So, I'm thinking 20W will go in & take care of the damping issue.
Opinions/experience?

[tkent02]

as I come to a complete stop, I'm getting a "second bounce", as the front fork settles.

It's not a damping issue, it's a riding issue.

[Grimly]

Rebuilding the XJ9 forks, I discovered I didn't have the second bottle of fork oil I was sure was there. I put 5W40 synth engine oil in them.
It's absolutely fine so far, and I'm leaving it in over the winter to see what happens.
Funny thing is - the sky hasn't fallen in, and I haven't tipped myself off the bike - it rides great for general scratching around.

[Steve]

What you are tying to control there is a rather low-velocity movement.

Picture what's going to happen when that 20w hits a bump at speed.

You will think that you filled the forks with concrete, not oil.

I know you are already regretting not getting the Sonic springs, but you might just have to suck it up and get them the second time around.

How much is the front "sagging" when you get on the bike? You are looking for 20-25% of travel. On our bikes, that means about ONE INCH of 'sag'. If you are getting more than that, I would try adding some preload, rather than increasing oil viscosity. If that doesn't quite do it, remove the springs, cut off some of the closely-wound coils. Add spacer length to compensate for the missing coils, try again. The object here is to get the SPRINGS to handle the weight, not the oil.

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[alke46]

So the sonics are better than the progressives? Just asking as I'm going to be upgrading mine also.

Are the sonics actually better or is it just a better deal price wise?

[Steve]

Think of it this way:
No matter which set of springs you choose, there will be some air trapped inside the forks. Air is a progressive 'spring' when it is compressed. The Progressive brand springs are also a progressive-rate spring. The two progression rates add up to some rather interesting characteristics as the forks are compressed.

Sonic springs are straight-rate springs. You still have air, with its progression, but now there is only one progression rate in play, so things run a LOT smoother and more predictable.

Look at the Sonic site, there is a calculator that will help you determine the spring rate that you need.
For what it's worth, the owner of Sonic Springs is Rich Desmond, a member here on GSR.

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[azr]

So the sonics are better than the progressives? Just asking as I'm going to be upgrading mine also.

Are the sonics actually better or is it just a better deal price wise?

Sonics are a straight wound spring rather than a progressive which is a mixture of both. I've had progressives which worked fine but as my riding skills improved I was soon able to out ride the front springs, meaning they would bottom out or close to it, too much movement in the fast corners, etc... I have sonics and they are the world of difference, tighter, better handling, etc....same price for either spring but way better results from the sonics. I have 3 sets of progressives if anyone is interested, lol.

[RichDesmond]

I've noticed, as I get things sorted out & drive more assertively, that as I come to a complete stop, I'm getting a "second bounce", as the front fork settles. I've put progressive suspension springs & 10W betray fork oil in the GK's forks.
If I had it to do over, I would have gone with straight rate Sonic springs. Sorry.
So, I'm thinking 20W will go in & take care of the damping issue.
Opinions/experience?

I wouldn't change the fork oil weight for that reason alone. A much more important test is how the bike feels when leaned way over on long, bumpy sweepers. If you're getting a "porpoising" or "hoppy-horseing" sensation there, then consider thicker oil.
If you do decide that you need more damping, try 15w first. 10w to 20w is a very big step.

[alke46]

Think of it this way:
No matter which set of springs you choose, there will be some air trapped inside the forks. Air is a progressive 'spring' when it is compressed. The Progressive brand springs are also a progressive-rate spring. The two progression rates add up to some rather interesting characteristics as the forks are compressed.

Sonic springs are straight-rate springs. You still have air, with its progression, but now there is only one progression rate in play, so things run a LOT smoother and more predictable.

Look at the Sonic site, there is a calculator that will help you determine the spring rate that you need.
For what it's worth, the owner of Sonic Springs is Rich Desmond, a member here on GSR.

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Sonics are a straight wound spring rather than a progressive which is a mixture of both. I've had progressives which worked fine but as my riding skills improved I was soon able to out ride the front springs, meaning they would bottom out or close to it, too much movement in the fast corners, etc... I have sonics and they are the world of difference, tighter, better handling, etc....same price for either spring but way better results from the sonics. I have 3 sets of progressives if anyone is interested, lol.

Thanks, you both have cconvinced me. It's sonics for my upgrade. Will probably have to do the shocks as well to complete the process.