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Re: [ST] Fork Oil Heights, Pre-Load and Front Sag



Big Snippage:

>I have been working on the ST for the past week or so with
>the front suspension.

The way you are measuring the front preload does not take into 
account sticktion of the front forks. Additionally the stock springs 
are .75kg not .65( and I believe progressive rate)  The problem with 
what I see you doing is that a .75 kg front spring is WAY light for a 
200 lbs rider ( which I also am) .75kg springs are good for up to 
about 170lb rider. When I had my front forks Raceteched I originally 
put in .95kg springs I was adding a fair amount of preload ( 
external) and found the front harsh. After spending some time futzing 
with oil weights, and emmulator turns etc I had the springs changed 
out to 1kg. The improvement was dramatically better. One may think 
that a stiffer spring will make the ride stiffer but that is not the 
case. A spring that is too soft for the riders weight and then a 
bunch of preload added in order to achieve proper sag will feel much 
harsher than the correct weight spring for the load. By having the 
wrong value spring for your weight one ends up all over the place 
with oil, or preload or what ever. If you really want to get things 
going in the right direction replace the springs with 1kg units. The 
ST's biggest short coming is IMO the crappy damper rod front forks. 
At least by going the Racetech route one can get the front end tuned 
to an acceptable level of performance. Since we've all ready done the 
hard part the setup for your weight would be as follows:
1kg springs
15mm internal preload spacers
125mm level
15wt fork oil (Ohlins)
2 turns on the emulators
Then set preload ( external) for 35mm of sag

Changing oil helps, if for no other reason than the stock oil isn't 
great stuff and it wears out ( fork oil should be changed yearly for 
best performance) but it's maybe 10 or 15% of what springs (60%) and 
Emmulators (30%) can get you. FYI 15wt (Ohlins) oil is THE hot lick 
with emmulators and springs. No question 15wt oil without the damper 
rods modified and emulators would be over damped. The difference 
between what you have and what it could be is not subtle.

Erik

 


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