Fork spring spacer length - how to calclate?

[Gio]

I'm in the middle of changing the fork oil on the V11S and thought would add a little pre-load to reduce the sag. I measured this beforehand at 124 - 86 = 38mm (I weigh around 175lbs) and would like to reduce this to say 30mm - so should I just increase the stock spacer length by the difference (ie 8mm so from the stock length of 109 to 117mm) or add a little more than this?

 

I'm also planning to raise the forks by up to 10mm - so I was thinking that in order to maintain the front ride height I should perhaps factor this in as well (so this would give a total of 18mm - close to that given by Doc in an earlier post - is that how you calculated your increase Doc?

 

Gio

 

PS - And yes Rich - I will be using some good old schedule 40 PVC tomato stakes...!

[Janusz]

I bet you did not take stiction into consideration Gio. See my post at the suspension setting thread.

Had you done it your averaged sag would be less, I am sure.

 

I would advice you to replace the springs with the heavier ones before you decide to play with the spacers and risk the soft spring binding.

 

If yoy still insist on installing longer spacers that will obviously decrease your sag and increase the ride height. Then if you raise the forks at the same time you will DECREASE the ride height so you have to deduct not add.

[RichMaund]

I calculated mine using the old technique of "Radcon Math". (That how we used to calculate does rates in radioactive work areas before going in to do the job.) ie; get it close. That's good enough to work with! I increased the length of mine by 1/3". Close enough was good enough in this case. It works better for me now.

I still have quite a bit of that PVC pipe here. (Tomatoes haven't needed staked yet.) If anyone wants some spacers cut to spec, just ask. They're yours for the postage!

[Gio]

Hi Janusz,

 

I think you are right. I just finished the installation of the Magni fairing (there's another story) and also made the following changes :

 

Replaced stock pre-load spacer (109mm) with +11mm (120mm)

New stock weight (10w) oil

Forks raised by 3mm

 

I measured the new front-end sag as 125 - 102 (average of 100 and 103 for stiction) = 23mm

 

Initial test ride felt much firmer but have not adjusted comp or rebound as yet.

 

Gio